The foundation is the most important part of a construction project as it provides a stable base to build upon. The price to install one varies, read below to learn more about the cost.
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2022 Concrete Foundation Costs
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|National Average Price||$ 8,000|
|Typical Price Range||$ 4,000 – $ 12,000|
|Minimum Price||$ 2,000|
|Maximum Price||$ 25,000|
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On this page:
- How Much does a Foundation Cost?
- Poured Foundation vs. Concrete Block
- Types of Foundations
- Concrete Slab
- Crawl Space
- Piers and Beams
- Full Basement
- Get a Minimum of Three Estimates
How Much does a Foundation Cost?
Although the average cost of a foundation is $4,000 to $12,000,  you need to consider which type of foundation you need to install to narrow in on the price.
Are you putting a foundation under an existing building? That will require the additional expense of raising the house to put in a new foundation. Replacing a damaged foundation? Are you building a foundation for a new home or putting on an addition?
Whatever the objective for your foundation, you can spend thousands before you ever pour the concrete or put together concrete blocks to form a wall. Much of that expense will depend on how much excavation, tree removal, and leveling will need to be done.
Poured Foundation vs. Concrete Block
The type of foundation installed will have an impact on the price. A poured foundation can be installed much faster than block. This is advantageous in areas where labor rates are high and the cost of concrete is low.
However, in some areas where the cost of labor is low and the distance needed to deliver ready mix is far then a block foundation might be less expensive.
The amount of concrete needed will also be a factor for a poured foundation. Concrete costs an average of $113 per cubic yard, but that varies by location and vendor. 
Types of Foundations
A foundation could be as simple as a concrete slab, or as complex as a full basement. The more familiar you are with how foundations get constructed, the better. You’ll want to understand which types are best suited for your area’s soil, climate, and flood conditions. Of course, your budget could very well affect which foundation you choose as well.
Of course, everything depends not only on the type of foundation, but there are other considerations such as preparation, leveling, labor, etc. You must also add in rebar or wire mesh, sealing, draining, humidifying, insulation, and other necessities.
Most monolithic concrete slabs are four inches thick, poured into a form, with or without rebar or wire mesh, and often placed over packed gravel. These are primarily used in areas with moderate climates, though some use these for garages, sheds, and barns, so there is less concern with frost and thaws heaving the soil.
The next step up from a concrete slab is a stem wall. This foundation’s construction is similar to a crawl space. Thick forms get placed on top of footings where the outer walls will be, with anchor bolts set into the form. The concrete gets poured into the forms, and when the forms get removed, the sill plates are attached to the anchor bolts.
We have an abundance of information about calculating concrete slabs, by the inch, foot, yard, or even by the bag. Always round up to the next yard or add 10 percent overage.
The monopour concrete slab is usually the least expensive, depending on size and how much you can do yourself. Figure $3-4 per square foot.
Stem wall slabs are about $5.00 per square foot. However, when you add the prep and labor, you can usually add around $10 per square foot for each type of foundation.
Homeowners use a crawl space as a less expensive foundation to get the house off the ground and to protect it from flooding. Crawl spaces require vapor barriers, insulation, and possibly a dehumidifier to avoid mold growth. These are usually 18 inches above the ground but could be as much as three or four feet, depending on the flood danger and other necessities.
Crawl spaces average about $7.00 per square foot. However, insulation will add another $1-3 per square foot, but a vapor barrier is much cheaper at less than a dollar. You could install a dehumidifier cheaper, but you will pay for the electricity to run it.
Piers and Beams
Piers and beams foundations are very similar to a crawl space. However, these usually get used in rocky or ledged areas where you might not be able to dig footings around the entire building, or when there is a chance of soil shifting. You can use drilled piers or spread footings, and then stretch beams across the expanse. These can also get added to repair damaged foundations.
These run about $5.00 per square foot, and you can use the same figures for insulation, dehumidifier, and vapor barriers.
A full basement is, of course, the most expensive option for a foundation. However, there are many benefits. These can be fully finished or unfinished. They can be used for storage or even contain a garage. Some homeowners add a full basement or finish an existing basement as a method of adding living space, a mother-in-law suite, or a rental.
A full basement has many variables. A new basement will require excavation down to eight feet. It can cost anywhere from $10-20 per square foot, and most spend $13,000 – $30,000 unfinished,  once again depending on the size. For a finished basement, figure about $25-100 per square foot or well over $100,000.
The price will go up when you need a separate entrance. A finished basement will also require a quality drainage system, waterproofing, and sealing the concrete, which is a good idea anyway.
Footings serve as the base of the foundation and provide support for the structure. Learn more about the cost of footings that are necessary for the foundation.
Get a Minimum of Three Estimates
The strength and durability of your house or project depends primarily on the foundation. Use our calculators to help you develop a plan, so you will know what a reasonable estimate is. Just don’t make your plan so “concrete” that you won’t change it when contractors present a valid reason. You should also consider getting multiple estimates from licensed contractors before you start the project – most suggest at least three estimates are a good idea.
All pricing information on this page is based on average industry costs, and is subject to variance for project-specific materials, labor rates, and requirements.
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Pouring concrete foundation is a considerably important phase of foundation construction and plays a vital role in the success of a project. Proper planning, suitable equipment selection, and good placement practice shall be adopted for concrete pouring of foundation to make sure that it corroborates the drawings and specifications.
Although the details and consideration are not entirely the same for different foundations such as shallow and deep foundation, however, essential practical considerations and pouring procedures are similar. Greater details regarding pouring of concrete can be found in ACI 304R-00 (Guide for Measuring, Mixing, Transporting, and Placing Concrete).
Planning for Pouring Process
Adequate planning is crucial since it guarantees sufficient and consistent supply of concrete. The Adequate placement capacity shall be insured to prevent cold joint formation during concrete pouring. Here are some points one should be heedful of when planning to pour concrete :
1). Concrete pouring machinery shall be cleaned and kept in good condition. To avoid unnecessary delays, concrete placement equipment should be arranged in an organized way and the manpower should be enough to ensure the proper placement, consolidation, and finish of the concrete.
2). Concrete should be delivered to the site at a uniform rate compatible with the manpower and equipment being used in the placing and finishing processes.
3). Concrete placement should not begin when there is a chance of atmosphere reaching freezing temperatures, unless adequate facilities for cold-weather protection have been provided (ACI 306R). Curing measures should be ready for use at the proper time (ACI 308).
4). Finally, detailed inspection of the foundation, construction joints, forms, reinforcement, and any other embedments in the placement should be made immediately before the concrete is placed.
Prior to the start of concreting, forms should be protected from deterioration, weather, and shrinkage by proper oiling or by effective wetting. Form surfaces should be cleaned and of uniform texture. When re-utilization is allowed, formworks shall be properly cleaned, and oiled. Lastly, it is recommended to apply oils to the formwork before reinforcement and other embedments are placed.
Reinforcement and Embedded Items
At the time of pouring concrete, reinforced steel and embedded items should be clean and free from mud, oil, and other materials that can adversely affect the steel’s bonding capacity.
Correct size, length, splices, and position of reinforcements and sufficient concrete cover shall be checked. Bars and embedded items should be held securely and the supports shall be adequate to carry expected loads before and during concrete placement.
Selection of Concrete Pouring Equipment
When choosing concrete placement equipment, consider the ability of the equipment to place the concrete in the correct location economically without compromising its quality.
Equipment selection is influenced by the method of concrete production. Certain types of equipment, such as buckets, hoppers, and buggies suit batch production; whereas other equipment, such as belt conveyors and pumps, are more appropriate for continuous production.
Before concrete pouring begins, care shall be taken to prevent concrete stream separation due to free falling over rods, spacers, reinforcement, or other embedded materials. Concrete should be deposited at or near its final position because it tends to segregate when it has to flow laterally into the place.
Internal vibration is the most effective method of consolidating concrete for most applications. Vibration machine should be inserted and withdrawn vertically so that they quickly penetrate the layer and are withdrawn slowly to remove entrapped air.
Concrete re-vibration can be carried out till running vibration machine sink into the concrete under its self-weight. Re-vibration of concrete improves compressive and bond strengths.
Construction joints are observed wherever concreting is stopped or delayed and freshly poured concrete fails to integrat with the previously placed concrete.
Horizontal construction joints form at the levels between lifts, whereas vertical joints occur where the structure is of such length that it is not feasible to place the entire length in one continuous operation.
The surfaces of all construction joints should be cleaned and properly prepared to ensure adequate bond with concrete placed on or adjacent to them.
Finishing Concrete Surface
After concrete compaction, the operations of screeding, floating, and first troweling should be performed in such a manner that the concrete can be worked and manipulated to gain the desired result.
If you’re building a new extension to your house, then you need to know how to form a concrete foundation floor. Concrete foundations can be poured into any part of your house; however, it’s important to make sure that the pouring is done properly so that the floor will last for many years to come.
The stability of the concrete foundation affects the structure and integrity of the whole building. If there are any weaknesses in the foundations, they will detriment the building. Laying and forming concrete foundations is actually very easy with the right tools.
Step 1 – Work Out the Size
Calculate how deep you need to dig the whole for the concrete slab. The thickness of the slab normally depends on the size and the application of the extension. If it is a garage, then it will typically require a thicker foundation. Use a measuring tape to measure the size of the proposed concrete slab and make sure that it’s the right size for the room in question.
Step 2 – Excavation
Dig and excavate the area of the foundation slab. Dig down twice the thickness of the slab. If you are going to make a slab which is 3-inches thick, then you will need to dig a hole which is at least 6-inches deep.
Step 3 – Cleaning the Hole
Once you’ve dug your hole, you need to clean it up. Remove any stones in the hole. Compress the soil by using a compactor. Compactors can be rented from many building companies. Put sand or gravel inside the hole. Doing so helps drainage, which prevents water from disturbing the slab.
Step 4 – Laying a Barrier
A barrier material needs to be laid to protect the concrete flooring. Ding so is especially important if you are laying the concrete foundation inside your house. Barriers are important to prevent moisture from seeping upwards through the concrete flooring.
Step 5 – Making a Frame
Construct a frame made from wood to retain the concrete. Use more sections of wood as screed rails to ensure the floor is level. When doing so, ensure that the wood is straight and not bowed. The frame needs to be complete so that the concrete can’t spill out.
Step 6 – Pouring the Concrete
Concrete can be mixed in a cement mixer, then poured into your wooden frame. The screed rails make it possible to level the concrete. Use hand trowels to finish off the job.
Wait for the concrete to set properly. Wait at least 2 months before laying a new hardwood floor. Use a sander to remove high or low spots in the concrete flooring.
- Working Time: 1 – 3 days
- Total Time: 3 days – 1 wk, 3 days
- Yield: 4-in thick, 9 sq-ft slab
- Skill Level: Intermediate
- Estimated Cost: $50 to $75
Concrete slabs are multi-purpose surfaces for homes and gardens. Used for walkways, patios, and floors, concrete slabs are inexpensive to install and durable enough to last for years. When you pour your own concrete slab, you’re giving yourself a design material that is adaptive to many of your outdoor design needs, while saving money that would have been spent on a contractor.
Working With Ready-Mix Concrete
For most do-it-yourselfers, the best material for building a concrete slab is a ready-mix crack-resistant concrete product. The wet mix is poured into a prepared wood form, then left to cure. After the concrete has hardened, the sides of the form are knocked off and the slab is ready to use.
Ready-mix concrete is a blend of gravel, sand, cement, and other additives. Bagged and available in most home centers, ready-mix concrete contains all of the materials to make concrete, except for the water.
To avoid setting a reinforcing bar (rebar) for strength, buy crack-resistant ready-mix. Its synthetic fibers eliminate the need for rebar on small-scale concrete slabs.
Working concrete by hand in a wheelbarrow requires strength, organization, and speed. For this 3-ft x 3-ft slab, you will need two assistants. Two people will mix the concrete in the wheelbarrow, while the third person spreads out the mixed concrete in the form.
When to Pour a Concrete Slab
Wait for dry, warm conditions to pour your concrete slab. For most ready-mixes, the temperature should be 70° F or higher for five days after pouring. You can pour the slab in colder temperatures (50—70° F), but the curing time will be extended to seven days.
Always use breathing protection when working with dry concrete mix since it is an irritant to breathing passages and lungs. Eighty-pound bags of concrete are very heavy, so have help when moving them to protect your back.
A slab foundation is a simple concept. Basically, it’s a concrete pad poured on the ground so in theory, it’s well within the skill set of a competent DIY’er. However, because you don’t get any ‘do overs’ when pouring a foundation most people wisely opt to contract the job out to a professional. However, to give you an understanding of what is involved in the process here’s an overview of how to pour a slab foundation.
Pouring a slab foundation
Start by laying out the outline of your foundation. Figure out where the corners are located and drive stakes into the ground at each corner, then run string between the stakes. These strings will be the outline of your foundation.
Inside the strings dig a trench 18” wide and at least 2′ deep (in colder climates you need to go down deeper to get below the frost line – usually 3 to 4 feet). This trench will form the footings for your foundation and provide the support for the walls of your building.
Around the trench build wooden concrete forms using 2” x 10” boards. Brace the forms every 2” using wooden stakes behind them.
Install rebar into the perimeter trench in a continuous line at least 2 inches from any outside surface. Overlap the rebar and join the pieces together using rebar wire to keep the rebar line continuous. Lift the rebar from bottom of the trench by setting it on ‘rebar chairs’ every 12 inches.
Spread a layer of sand or gravel covering the inside of the slab form 4 to 6 inches deep. Level the gravel then cover the interior of the surface of the pad with 6 mil plastic to help control moisture infiltration after the concrete pad is poured.
Install rebar in a grid pattern again being sure to keep it elevated using ‘rebar chairs’.
Conduit for electrical wiring, water and drain pipes is installed above the plastic sheet making sure they are up from the bottom of the slab before pouring the concrete slab is poured.
Fill the footing forms with concrete and use a piece of 2” X 4” to level it. Install anchor bolts every 12”.
Continue pouring concrete into the center of the form creating a concrete pad 4” to 6” deep and level with the top of the exterior footings. Use long handled trowels to smooth the interior pad.
Allow the poured concrete to set up for at least 48 hours before removing the wooden forms.
Local building codes will actually dictate the specific details of how your slab foundation is poured in your area. Details such as the thickness of the slab, depth and width of the footing, size and location of the rebar as well as the type of sand or gravel are commonly specified in local codes.
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The best way is to order low-slump concrete, which is concrete with a low proportion of water.
I’ve done a bit of concrete flatwork—stairs, stair landings for decks, some slabs, and so forth—but now I have a client asking for a concrete walkway in front of his house and one section of it, say about 10 ft. long, slopes downhill. It’s not super steep, but it did make me wonder if there’s anything I need to know about ordering, pouring, and finishing concrete on a slope. I have visions of the wet concrete all slumping at the bottom and hardening in a giant lump.
John Carroll, a mason in North Carolina, replies: The answer to your question can be found in the question itself. You’re worried about the wet concrete slumping downhill along the slope, so the best way to avoid this is to order low-slump concrete, which is concrete with a low proportion of water.
“Slump” is a term used to describe the consistency of the mix. In commercial work, a simple slump test of the concrete is often required in the field during the concrete pour. In this test, a 12-in.-tall steel cone is filled according to strict specifications. The steel is then slowly removed and the amount that the resulting cone of wet concrete settles, or slumps, is measured with a ruler. For example, if the concrete mixture settles 3 in., then it is said to have a 3-in. slump, or sometimes just a slump of 3. The stiffer (drier) the mixture, the lower the slump. The looser (wetter) the mixture, the higher the slump.
You don’t need to do a slump test for your project, but you can use the term to describe the mix you need when ordering. For a mild slope, such as the 1-in-20 slope required for a wheelchair ramp, a 3-in. slump will work. For steeper slopes, you will have to go to a 1-in. or 2-in. slump. If you aren’t sure, just describe the job to the concrete dispatcher, and they will tell you what slump to use.
From a structural standpoint, low-slump concrete is good. But it is hard to work with. Since it doesn’t flow, you need plenty of hands available to move it into position in front of the screed. And you need to float the stones down beneath the surface of the wet mix just after you place and screed it.
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There are many variations of concrete slabs depending on the purpose of the slab. Below are some useful links for understanding concrete foundations, along with the three types of concrete foundations.
A traditional foundation method to support a structure in an area where the ground freezes. A footing is placed below the frost line and then the walls are added on top. The footing is wider than the wall, providing extra support at the base of the foundation. A T-shaped foundation is placed and allowed to cure; second, the walls are constructed; and finally, the slab is poured between the walls.
- T-shaped foundations are used in areas where the ground freezes.
- First, the footing is placed.
- Second, the walls are constructed and poured.
- Lastly, the slab is placed.
As the name suggests, a slab is a single layer of concrete, several inches thick. The slab is poured thicker at the edges, to form an integral footing; reinforcing rods strengthen the thickened edge. The slab normally rests on a bed of crushed gravel to improve drainage. Casting a wire mesh in the concrete reduces the chance of cracking. A slab on grade is suitable in areas where the ground doesn’t freeze, but it can also be adapted with insulation to prevent it from being affected by the frost heaves. (see below)
- Slab on grade used in areas where ground does not freeze.
- The edges of the slab-on-grade are thicker than the interior of the slab.
- The slab-on-grade is monolithic (poured all at one time).
This method only works with a heated structure. It relies on the use of two sheets of rigid, polystyrene insulation-one on the outside of the foundation wall and the other laid flat on a bed of gravel at the base of the wall-to prevent freezing, which is a problem with slab-on grade foundations in areas with frost. The insulation holds heat from the structure in the ground under the footings and prevents heat loss from the edge of the slab. This heat keeps the ground temperature around the footings above freezing.
- Only works with a heated structure.
- Has the benefits of a the slab-on-grade method (concrete poured monolithically) in areas subject to frost.
- Concrete is poured in one operation, versus 3 pours required for T-shaped foundations.
All information about footings is from Sunset Books “Sheds and Garages”.
I’m building a 25-meter (65 foot) block retaining wall. The engineering specifications require a concrete foundation for the block wall equal to about 4 cubic metres (141 cubic feet) of concrete, with reinforcing bar/mesh throughout. This includes 10% waste.
Due to access problems on our (rural) property, the premix concrete supplier will need to make multiple deliveries with a small truck. However, they won’t guarantee the deliveries will all arrive within a particular time window, or even on the same day. I don’t want to get halfway through pouring a single foundation only to find out the next delivery won’t be for another day.
My proposed solution is to pour the foundation in multiple sections to guarantee each section will be completed in a single pour. Reinforcing bar runs between sections joining them together, and formwork used to hold each section in place until the next section is ready to pour.
Can I pour the foundation in a number of smaller segments which are joined by the reinforcing bar but poured on different days, or will this result in a severe structural problem for the wall sitting on the foundation?
Is a better approach to hire my own mixer and pour many small sections, similar to what is described in this question?
6 Answers 6
I agree with Ecnerwal, yes you can do that. I also agree to extend the rebar past the pour (drill holes in the form boards and extend the rebar out the holes).
Code (and CSI) require 30 bar diameters. So, if you’re using #4 bar (1/2” diameter), then you need to extend it a minimum of 15”.
Yes, you can do that. Provide plenty of rebar length past the joint. The vast majority of commercial projects are poured in sections, and virtually everything more than 60-70 years old was poured in sections.
As others have said, the first thing to do is to carry the reinforcement beyond each “day” joint to give continuity of reinforcement.
As long as adjacent concrete sections are poured within approximately 3 days of each other, the individual sections of concrete will fuse as the concrete cures and the cement hydrates to create a single contiguous piece of concrete.
Yes. To get better results please do the following:
have rebars continuously, or leave an adequate splice length, across the joint.
at the end of the leading pour, prepare the joint with a little slant and roughen the surface, then cover the leading pour with plastic sheets.
on the day of the second pour, clean the joint with a water wash and wait till the solid concrete appears to be moist but surface dry (no hanging water). You can fasten the drying time by spreading/applying a thin layer of cement on the joint that would absorb the water and help bond the concrete of different ages.
wet curing the concrete at least 7 days after the last pour.
Side View of the Concrete Footing:
Note: If you choose splice over continuing the rebars, please check with your engineer or the local code regarding the splice length requirement.
In addition to the rebar extensions you may consider applying concrete bonding adhesive depending on the time between pours.
Based on that and what we learned, this would be my approach to your problem:
First, the biggest issue by far, is steel close to the surface or crossing a join. Your problem then becomes,how to be certain that water can’t flow (however slowly,even through a join), and over time cause corrosion and degradation.
There are systems for that, but they tend to be specialised and often, expensive.
Your supporting concrete (4 cu.m over 25m length) is equivalent to 0.16 cu.m. per linear metre, or for example,a footing 40 x 40 cm (or 25 x 60 cm etc) along the whole 25m length. The structure supported, is a retaining wall.
A wall that length, the footing is providing ground support. It almost certainly doesn’t matter if its actually cast as 3 x 8.3 m sections, because the ground load spreading will be identical. The middle part isn’t relying on the end parts for support, because it’s too long and thin – if it needs support, it will have buttressing designed in, by the engineer,it won’t rely on full length steel for it.
So I would check with the engineer, is it okay to cast the footing as say, 2
12 m each. In each section, stop the steel 70mm before the end, and restart it 70mm into the next section.
I would expect this to give identical results with no risk, and no need to take protective measures for the joints. It will still look and act exactly as the original design would have done. (It sounds like).
At the absolute worst, you gain control joints every 6
12 m, which is a good idea anyway. It means that if the ground was going to have poor support in an area (could be likely over a 25m run?), the original would quite possibly have uncontrolled cracking, exposing steel. Very bad idea. This way, each section is shorter and much more likely to act as a whole, under stress. Any cracking will manifest at a section end, where steel won’t be exposed. If that kind of settlement happens – it would have happened anyway, most likely and this way is likely to control it better and make it much easier to make good.
How deep does a concrete foundation need to be?
Wall Footing Thickness.
For masonry or concrete construction, the minimum foundation wall will be 6 inches. The minimum reinforced concrete footing thickness will be 6 inches or 1-1/2 times the length of the footing projection from the foundation wall, whichever is greater.
Can you pour concrete directly on dirt?
Long story short, yes you can pour concrete over dirt.
How deep do you pour footings?
In areas with freezing winters, a concrete footing usually must extend at least 12 inches below the frost line (the depth at which soil freezes). A footing should also be at minimum 8 inches thick and twice as wide as the wall or posts it will support.
Do you need gravel under concrete?
Whether you pour concrete for a walkway or patio, a strong gravel base is required to prevent the concrete from cracking and shifting. Gravel is especially important in clay soil because it doesn’t drain well, which results in water pooling under the concrete slab and slowly eroding the soil as it finally drains.
What type of concrete is used for foundations?
High-Strength Concrete Mix: When durability is key, high-strength concrete makes a great choice. This is ideal for foundations, footers and heavy equipment bases.
Should I put plastic under concrete?
Recently, though, research has shown that the old traditional layer of 6-mil Visqueen (polyethylene plastic) under the slab is seldom effective for two main reasons: Although it may seem water-tight, this grade of material allows a lot of water vapor to pass through.
Do you need rebar for 4 inch slab?
No, you do not need rebar for a 4–inch slab of concrete on grade. A 4–inch-thick slab cast on the ground and in permanent contact with it will float and rebar is not required. Rebar is recommended on concrete measuring 5 – 6 inches thick.
Is Clay a good base for concrete?
The clay can compress under the weight of the concrete, causing the slab to shift or sink over time. It also can leach moisture from the concrete itself, resulting in uneven curing and a brittle base. With proper preparation, however, it’s possible to pour a slab on clay soil without encountering these problems.
Why deck posts should not be set in concrete?
A deck post should always be placed on top of footing, not inside concrete because it can break. Concrete tends to absorb moisture and wood expands when it gets wet, so these two factors combined will result in the wood breaking the concrete.
Can you use concrete blocks for footings?
Ensure a solid footing. Footings should be a minimum of twice the width of the concrete block (i.e., a typical 8x8x16 block would require a 16-inch wide footing) and extend below the frost line. NOTE: it is important to check local building codes for construction requirements in your area.
Do footings need rebar?
Using Rebar for Concrete Deck Footings
Plain concrete deck foundations without rebar are acceptable under the minimum standards of construction established in the International Residential Code. Footings with large bearing areas or unstable soil can benefit from adding rebar to prevent cracking.
What are the 3 types of foundations?
But chances are your house has (or will have) one of these three foundations: full basement, crawlspace, or slab-on-grade. Other variations are possible. Here are the three main types of house foundations that you will encounter in residential construction.
What is the standard footing size?
Under every house is a foundation, and under most foundations are footings. Most of the time we take footings for granted, and usually we can: For typical soils, a common 16- or 20-inch-wide footing can more than handle the relatively light weight of an ordinary house.
How do you calculate footing size?
How to Calculate Footing Size
- Determine the width and length of the cement slab in inches.
- Divide the width by 12 to convert it to feet.
- Divide the length by 12 to convert it to feet.
- Determine the depth or thickness that is required for the footing in inches.
- Multiply the width by the length and then by the depth.
September 4, 2020
How to pour concrete footings and piers, with step-by-step instructions for building a form and ready-made concrete pier options.
Waxed fiber tubes, readily available at home improvement centers and lumberyards, make forming and pouring footings and piers a relatively easy job.
It’s also easy to build a simple form from lumber scraps, as shown in the photo. Be aware that, by some codes, you may be required to have the footings inspected before making the piers, or you may need to add several inches of gravel to the bottom of each footing before adding concrete.
Dig and pour all footings and piers at one time, if possible. Have rebar and anchor bolts or post bases on hand, as you must add them to the concrete while it is still wet. Lay out the footings. The spacing between footings for support posts is determined by post placements, which are a factor of beam spans.
In areas with freezing winters, a concrete footing usually must extend at least 12 inches below the frost line (the depth at which soil freezes). A footing should also be at minimum 8 inches thick and twice as wide as the wall or posts it will support.
Fiber Tube Forms
To build a form from a fiber tube, begin by digging a flared hole, sized as required by code, using a clamshell digger or a power hole auger.
Cut a length of waxed fiber tube (in some cases, fiber tubes can be difficult to locate; instead, you can form rectangular footings from scrap plywood or wood) long enough to extend 2 inches above grade and 2 inches into the flared footing at the bottom of the hole. Level and suspend this tube in the center of the hole by screwing it to temporary braces.
Next, fill the flared section of the footing and the bottom 2 feet of the tube with concrete. Using a piece of wood, agitate the mix to remove any air pockets. Repeat the process every 2 feet, until the tube is slightly overfilled. Smooth the surface by moving a short 2 by 4 from side to side across the top.
Add rebar according to code requirements, typically two pieces of #4 rebar spaced about 2 inches from the fiber tube. Each should be long enough to reach from the bottom of the footing to about 2 inches below the pier’s surface. Insert an anchor bolt, post base, or short rebar “pin” for centering the post, and check it for alignment.
Depending on the type and size of project you are building, you may be able to set a ready-made concrete pier on a footing. Choose the type of piers with integral metal post anchors. When setting a pier, be sure to account for its height above ground and its depth below the frost line. ©Don Vandervort, HomeTips
Soak the piers with a hose, and then place them on the footings five to 10 minutes after the footings have been poured, when the concrete is stiff enough to support them. Then, with the post anchors properly aligned with your string lines, level the piers in both directions.
Keep the concrete damp for two days, allowing it to cure slowly. Then remove the temporary braces, backfill the hole with dirt, and cut away the exposed fiber tubing.
We broke ground for our new house, and now week 1 we form and pour the foundation footings. The first step is excavation, then building the footings forms, and pouring the concrete in the forms. Here is a weekly progress of our house building process.
This past week was all about getting ready to pour the foundation footings. By last week Thursday the hole was dug. We hired a local company to dig the hole for the foundation, and we will also get them do to the septic and civil work.(If you are new here, my name is Jessica! My husband and I built our own home, acting as our own general contractors. We live in rural Ontario, about an hour south of Ottawa)
We are building a raised bungalow and we plan on using the basement as living space. Tony and I wanted the basement to be high with big windows, so the hole only needed to be 4 feet deep.
Building Footing Forms
Then all week this week Tony and our contractor, along with Tony’s father, worked on building the forms for the footings. We hired Dovetail Carpentry to do a lot of the work for us. He is a good friend of ours and he is very good at what he does. These are the finished forms.
Then we got some gravel around the edges of the forms so the concrete wouldn’t spill out the bottom of the forms.
Pour foundation footings
The next step was to pour the foundation footings. There were seven of us working there, and it still took most of the day. Tony and I are newbies when it comes to general contracting, so we’re still working on our estimating skills. At first we underestimated the amount of rebar we needed for in the concrete, then we overestimated the amount of concrete. Now we have some very expensive fill under our garage.
And this is how it looks at the end of this week. Next week we will start the foundation, as long as the weather cooperates!
How To Pour A Concrete Footing TIPS
- Soil must be strong
- Bottom of footing below local frost level
- WATCH step-by-step videos below!
- Steel rods in concrete are a must
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This spring you may have ambitious plans to build that long-awaited DIY room addition, shed or detached garage.
Many a homeowner just like you has successfully completed one of these smaller projects.
All structures need a great foundation so they can stand the test of time.
Foundation walls almost always are supported by a footing, or footer.
Footing Is First
The footing is almost always the first thing one does when building anything.
The bottom of the footing is what touches Mother Earth. It’s no different than your foot, hence the name.
The purpose of a footing is to spread out the weight of the structure onto the soil. The foundation wall rests on this footer. Most common footings for houses, room additions, detached garages, etc. are 24 inches wide and no less than 8 inches thick.
You can access a handy quick start guide for concrete footers with more tips and a full tool list here: Concrete Footer Quick Start Guide
Degree of Difficulty:
Concrete Footing Step-By-Step Videos
Watch these videos to see the entire process of forming and pouring footers. You may be doing a trench footer where trench walls become the forms. These require you to stand down in the concrete if you have a frost depth that exceeds 24 inches.
After watching the videos, then continue to read for extra detail that may have been skipped in the videos.
Permits & Frost Depth
Check with your local building department concerning building permits, and the frost depth in your area. The bottom of the footer needs to be below the frost depth. It’s always a great idea to go just a little deeper than recommended.
Be sure you locate and identify any underground utilities before you dig. Call 811 and have all utilities marked so you don’t get hurt or cause neighbors to have problems if you slice into a buried electric, water or gas line.
Be sure you double check the footer is square before you dig. Layout the foundation on the ground before digging.
When the diagonal measurements are the same in a square or rectangular foundation, it’s square! Watch this video about squaring up a footing or a wall.
Watch this video to see a neat trick using some long 2x4s. You can build a box that represents the actual outer shape of your finished foundation. Make sure the lumber is straight, square it up and then spray paint a line about 8 inches on the outside of the box to represent where you need to dig your trench.
If you footing is going to be 24 inches wide, most are, and your foundation is 8 inches thick, that means the footing extends 8 inches beyond the outer line of your foundation wall.
Digging Is Work
You can dig by hand, I’ve done it for many a footer, but tool rental businesses now rent very small excavators that can fit in a small yard. You don’t need a full-size backhoe to dig a shallow footer.
If the soil smells like rotten eggs, is squishy or you sink in it even when you get down to the desired depth, STOP and get a professional opinion. You may have to dig deeper to get to STRONG soil or you may have to install piers. Smelly soil often means there’s lots of organic material rotting in the soil. This will cause a foundation failure in the future.
Steel Is A Must
Footers need long pieces of reinforcing steel. One-half-inch diameter, #4, is almost always sufficient. This steel needs to be continuous through the entire footer and be held up at least 3 inches from the soil. Overlap splices at least 16 inches.
The footer should be at least 8 inches thick. Most architects call for a footer to be 20 inches wide, but I always poured mine 24 inches wide. Wider is better because it spreads out the weight of the building onto the soil
You can just pour the concrete in a 24-inch wide trench if you like. It’s key the concrete is very level.
Drive vertical pieces of reinforcing steel into the soil every 4 feet in the center of the footer as leveling reference points. Use a laser level or builder’s transit to get the tops of these pins at the same height.
Have plenty of help on hand when the concrete truck arrives. Be sure to have spare wheelbarrows in case one breaks.
Don’t overfill wheelbarrows as concrete is very heavy. Consider renting a small machine with a bucket that you can use to make trips from the concrete truck to the footer.
Wear rubber boots if you’re working in the trench to level the concrete. Concrete will cause burns to skin, so wash off any as soon as possible. Use a simple wood float or magnesium float to smooth the concrete.
No one task, other than digging the hole and wheelbarrowing the concrete, is really hard in this job. It’s all a matter of common sense and thinking the job through.
Now you know concrete is versatile. One of the most common uses of concrete is using it when making a foundation for any structure. Especially your new home! Let´s consider the steps involved when you are building your custom made home or when a builder makes the model you choose.
With modern technology, we have these huge machines to do the monster work. You will need to hire a licensed excavator to prepare the land. Depending on what type of land you have, you want to build on solid ground. Many do a ground survey before deciding on what type of foundation is needed to have a stable home.
Footings are part of your core structure. They are created by forms that help make the shape of the concrete. They are the load bearers for the walls and posts. The size of the footings will vary depending on the design of the house. There are wall, column and stepped footings. Wall footings support the weight from the walls. The columns support the posts which in turn the beams that support the floors. The steeped footings are for sites that have sloped sites.
Once the footings are good, the forms are taken off ready to pour the walls. A form is also installed for the walls. There are various types of forms and your builder will know which kind to use.
Once the walls are ready, the forms need to be stripped off. Now the most important part for you basement is the waterproofing. This requires applying a product that produces a thick sticky tar-like substance that cures and acts as an impenetrable membrane. This is guaranteed a dry basement. After, installing a draining tile is essentially as important. This guarantees any water that seeps into the soil to drain away from the foundation, preventing any water or moisture damage to enter in your home.
Finally, once the drainage system is installed correctly and the waterproofing has been properly applied, the concrete is poured. You will have to wait a few days to make sure the concrete is fully dry or solidly in tack before continuing further.
Once the installation of the subfloor is complete, this is when the area around your foundation will be backfilled. When the soil is put back around the foundation it is graded in a matter that it slopes away from the foundation. Now you are ready to build upwards.
Building your own home can be very stressful but with the help of choosing the right contractors to do the job you will end up with a priceless, satisfying feeling.
Whether you are pouring a patio, a base for a shed, or some other concrete project, the most important steps happen way before the concrete truck arrives.
Read on to learn how to prepare your space for pouring concrete.
Preparing the Soil for Concrete
The soil you build your concrete pad on needs to be compact and well-drained to ensure the best concrete slab results.
Concrete is a porous material so drainage can’t be an issue. Otherwise, water under the concrete pad will result in stress cracks in the cement as the ground flexes.
When you take the steps to prepare the subsurface, you limit the risk of cracks in your finished concrete.
Make a Stable Base for the Concrete
Generally, a 4-6 inch compact base is good for pouring concrete. But if you are pouring a driveway and have an RV you’ll be parking there, you may need to readjust to 10-12 inches.
If you have sandy soil, you’re in luck. All you’ll need to do is scrape off the sod and topsoil and add gravel fill if needed.
Yet, if you live in cold climates or have heavy clay soil, you may also want to make your base layer between 10 and 12 inches.
Your local concrete supplier can help you figure out the right base depth for your geographical area based on your intended use.
Your municipality might also have guidelines on base depths for your area.
Prepare the Site for Pouring Concrete
Next, contact your municipality and see if you need a permit. You can also find out how close to your property lines you can build.
Then, drive four stakes to indicate the corners of your slab. Use a line level and string to find out how much the ground slopes.
If your site is sloped, you will need a lot of soil to make it flat. You might also need to build up a low section.
Build up the Concrete Formwork
You will need to create a box out of wood so the poured concrete can take shape.
Choose straight form boards that are the right size for your project. If you are pouring concrete for a shed or garage, 2×12 boards work very well. For a driveway or patio, 2×6 boards work best.
You might need to splice some boards together to get the length you need.
Levelling the Ground For Concrete
Use a builder’s level or a laser level to set the height of the forms. Poured concrete can bend your form boards out and ruin the shape you want.
You’ll need to add extra strong supports by using 2×4 stakes and 2×4 kickers every two feet down the lengths of the forms.
You will need to use a lot of care when doing this step. Remember, your poured concrete will take the shape of this box. Building this form straight is crucial.
Learn more about how to build a straight form before you move on to the next steps
Dig & Smooth Out the Ground
Next, dig the ground to the proper depth for your concrete pad. You may want to rent a skid loader or hire an excavator if you need to move a lot of dirt.
Smooth out the ground with the flat side of a rake to level it. Use dirt to fill in low sections.
Compact Each Layer of Concrete Base
Use a vibrating plate compactor and pass over the base three or four times. Then add another two inches of base and go over the plate compactor again.
Make sure you use a compactor that is for compacting a base. Compactors, such as rammers or jumping jacks, are for backfilling trenches. That’s not what you need when prepping for pouring concrete.
Dampen the Base
Dry base won’t compact well during the next step. If you are working in dry conditions, spray each base layer with a hose.
You can test to see if your base soil has enough water by grabbing a handful. Make it into a ball. The soil will be ready when it keeps shape when you open your hand.
If it crumbles, you’ll need more water, but don’t make pools of water because that will not help your base either.
Tamp the Base
Once you have your base the height you need, it’s time to tamp the ground. You can use a mechanical tamper that you can rent from your local hardware store, or you can use a hand tamper.
A hand tamper is a heavy pole that has a flat metal base and two handles. You’ll use it to pack down the soil.
Test the soil by walking across it. You should barely leave any footprints.
Once your base is compacted, add two inches of small gravel to help with drainage.
Tamp the gravel down so that it is flat and smooth.
Get Ready to Pour Your Concrete
Congratulations! You made it to the final step of this complex process. It’s time to have a truck come to deliver and pour your concrete. Reschedule delivery if it is hot, windy, or rainy.
You’ll need several strong helpers because you need to work fast.
Start by placing concrete in the concrete forms farthest from the truck. You may need to use heavy-duty wheelbarrows for large projects.
Pour the concrete as close to where you want it to go. Roughly level it with a rake. Continue until your form is complete. Then flatten with a bull float and round the edges with an edging tool.
You’ll then smooth the entire surface with a trowel and wait for your poured concrete to dry.
Now You’re Ready For Your Pouring Concrete Project!
There you have it! These are all the steps you need to prep for your project that requires pouring concrete.
Though this project is labor-intensive, you can save big bucks by doing this work yourself.
The Concrete Foundations Association explains how commonly and effectively residential concrete foundations are constructed during the winter.
Question: Concrete foundation pours in cold weather will be affected by temperatures in the mid 30s to mid 40s or lower. How should I ensure my customers and our building inspectors that the walls will perform as designed? – Concrete Contractor (Wisconsin).
Answer: There is no denying that the vast majority of basement markets in the United States are turning colder; colder to the point of concern from customers, code officials and building inspectors as to what will happen to the concrete during these placements. A wealth of information has been generated in the past decade substantiating the recommended procedures necessary to produce quality foundation concrete during these conditions. Documents such as the CFA Cold Weather Research Report, ACI 332R-06 Guide to Residential Concrete, ACI 332-10 Residential Code Requirements for Structural Concrete, and ACI 306 Guide to Cold Weather Concrete all establish consensus for the contractor to proceed with both caution and confidence under cold weather conditions.
CFA member contractors know that in order for cold weather foundation installations to be successful, there are some hard rules to recognize and follow. Most of these are related to the supporting soil condition, but some do affect the concrete and form preparation.
We asked CFA member, Dennis Purinton of Purinton Builders in East Granby, Conn., about his thoughts on cold weather concrete foundations. “The four most important things to remember in cold weather concreting are 1) mix design, 2) concrete temperature, 3) CONCRETE TEMPERATURE and 4) the correct balance of accelerator to concrete temperature.” Dennis is a CFA Board member as well as a voting member on ACI 306 (I am also a voting member on ACI 306). Dennis is also the head of a new task force CFA has formed to research cold weather performance of residential concrete slabs.
What do these mean for you? Consider the following:
1. The excavation must be not be frozen and must also be free of frost. The foundation system is designed based on the strength or rather bearing capacity of the supporting soil. Frozen ground expands and therefore changes its support condition. Once frozen ground has received a structure, that structure is falsely supported by the expanded grade and will experience settlement as the ground thaws.
2. Concrete must be protected from freezing until it has reached 500 psi. It must be protected from multiple freeze/thaw cycles until it has reached 3,500 psi. The freezing point of concrete is in the neighborhood of 27° F, depending on the concrete mix. Concrete has remarkable strength gain characteristics due to the natural hydration process. Significant research conducted on full-scale wall elements by the CFA has resulted in a more thorough understanding of this performance.
This does not mean that concrete walls will not freeze, as they will and they may below the 500 psi benchmark. Contractors must also understand the behavior of even colder ambient temperatures that may flash freeze concrete or accelerate the temperature drop so that they can plan protection such as blankets and in the most severe cases, auxiliary heat sufficient to meet the strength gain goals.
3. Mix design must be considered a top priority for successful cold weather concrete. Water-cementitious material ratio is very important for success. Water is required for the hydration process and is consumed by it. However, water is also the culprit for freezing. The higher the water content, the more susceptible the concrete is to early freezing. Cement type is another important decision, such as Type III cement with characteristics of faster strength gain. Another aspect of the decision process for cold weather concrete is the use of admixtures. Calcium chloride and non-chloride accelerators (NCAs) are proven to be very effective at accelerating the hydration process, generating greater internal heat and thereby strength gain. The final important decision is temperature at production and delivery. The higher the concrete temperature at delivery time, the more likely 500 psi will be attained in very cold conditions before freezing. The CFA Cold Weather Report offers:
Contractors should work with their local ready-mixed concrete producer to design concrete mixes that will perform well based on the expected variables for a placement. The mix designs used in this research provide a sound basis for your own mix development but should be used after localized testing.
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Learn how soil conditions impact your choices around using concrete piers, poured-concrete footings, and slab foundations for spreading the weight of a strucutre.
Footings support foundation walls, spreading the weight of the structure evenly on the soil below and preventing foundations and the structures they support from buckling, sinking, or cracking. In many locales, footings are made of steel-reinforced concrete, but the International Residential Code (IRC) also allows footings to be made from crushed stone, and builders lucky enough to be working in parts of the U.S. with predictably stable soils may be able to pour extrathick foundation walls and skip separate footings altogether.
Soil type is an important consideration
Footing design springs from two variables: the weight of the structure and the bearing capacity of the soil. The heavier the building and the lower the capacity of the soil, the beefier the footing must be. As spelled out in Section 403 of the IRC, the presumed load-bearing capacity of soil ranges from a high of 12,000 psf (lb. per sq. ft.) for crystalline bedrock to as little as 1500 psf for clay and certain types of silty soils. When a building inspector suspects that the bearing capacity is less than 1500 psf, a soils investigation may be required.
Depending on the number of stories, the weight of the walls, snow loads, and the bearing capacity of the underlying soil, concrete footings for light-frame construction can range from 12 in. by 6 in. to 30 in. by 10 in. At the extreme end of the scale—
a three-story house with snow loads of 70 psf and poor soils—concrete footings may be as massive as 49 in. deep and 19 in. wide. The IRC requires that footings be no less than 12 in. below undisturbed ground and placed below the local frost line.
The code also permits crushed-stone footings. As with concrete footings, the bearing capacity of the underlying soil and the weight of the structure guide design. Crushed-stone footings for a two-story house—assuming the light-frame walls of the house weigh 1800 lb. per ft.—range from 6 in. by 15 in. to just 4 in. deep and 13 in. wide, depending on the soil. The crushed stone must be consolidated with a plate vibrator in 8-in. lifts. Crushed-stone footings are what Superior Walls likes to see for its precast concrete wall sections. They’re also used for permanent wood foundations.
Frost-depth steel-reinforced concrete footings are common in many parts of the country, particularly beneath basement foundations as shown here. Water-management strategies and insulation levels will vary by site and climate zone.
Let experience and location be your guide
Rhode Island builder and editorial advisor Mike Guertin is often able to do his own soil tests with the help of a penetrometer (a device that measures soil strength), or he relies on published soil classifications for the area. Soils in the areas where he’s used to working generally don’t require the help of an engineer, so Guertin takes his cue on sizing footings from the prescriptive tables published in the IRC.
In some situations, soil conditions are such in Rhode Island that Guertin can pour a 12-in.-wide foundation wall without separate footings. Walls might be poured on a 6-in. bed of crushed stone, or simply on undisturbed soil. With the right soil conditions, the 12-in. width of the wall meets the minimum footing requirements in the building code.
If Guertin is building houses on easy street, consider the difficulties that Texas-based designer Armando Cobo routinely faces in coming up with footings for the extremely expansive soils in parts of Texas where he works. There, he says, builders concern themselves with the “potential vertical rise,” or PVR, of the soil on a lot—how much the soil will go up (and then down) when it rains. The PVR determines the type of footing and foundation that will work on a particular lot.
When the PVR is estimated at 4 in. or less, a slab-on-grade foundation may work just fine. Between 4 in. and 8 in. of PVR, builders often go to a waffle slab, a monolithic pour with boxlike recesses cast into the bottom of the slab that absorb soil expansion when it rains, Cobo explained. This type of slab looks exactly like what comes out of a waffle maker, hence its name. When the PVR on the site is higher, say 10 in. to 12 in., a waffle slab might be supported by concrete-pier footings. Post-tensioned slabs—in which integral steel cables are tightened after the slab has been cast—are another common solution to lots with problem soils, as are pier-and-beam foundations.
Commonly used for decks and porches, poured-concrete piers can also be used for frost-depth footings for homes and other buildings. A spread base may or may not be needed depending on soil bearing capacity.
Slab foundations are another option
Most slab-on-grade foundations are poured as monolithic structures—the footings are an integral part of the foundation. A slab foundation can speed up the construction schedule and reduce the amount of concrete that must be ordered. One variety is the thickened-edge slab. Around the outside of the foundation, the concrete might be 10 in. or 12 in. thick, while concrete in the middle of the slab would be less than half that. The idea is that the thicker edge bears the weight of the exterior walls, just as a separately poured concrete footing would. Frost-protected shallow foundations and raft slabs are similar, but rigid insulation is used to prevent frost from getting underneath the slab.
This type of slab-on-grade foundation allows builders to form the footing and foundation in one pour. Depth and dimensions of the thickened edge will depend on frost depth and soil-bearing capacity. Insulation R-values and location as well as necessary drainage will vary.
—Drawings by Peter Wojcieszek
Learn more about footing in the article, “Footing Retrofit in a Day” from Issue #301.
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An outdoor fountain adds an elegant focal point to your garden, especially if it is surrounded by brilliant blossoms from a nearby bush or flower garden. Typically constructed of ceramic or stone, outdoor fountains must be relatively heavy so they can withstand the elements. But, coupling the fountain’s weight with running water creates an extremely heavy object that needs support on bare ground. Installing an concrete foundation provides the fountain with strong support to prevent toppling or sinking into the ground.
Measure out the length and width of your future foundation at the intended installation area, making sure the foundation’s dimensions are larger than the fountain’s base diameter.
Mark the four corners of your foundation with wooden stakes.
Remove any sod or topsoil from the marked area using a shovel. Continue to remove soil until you are approximately 6 inches below the surrounding area.
Place a hand level inside the cleared area. Confirm that this area is level. Smooth any bumps within the cleared area with the shovel to create a level surface.
Cut four two-by-eight wood lengths to the measured dimensions of your foundation using a saw. Press each wood length against the cleared area’s soil walls to create a solid form. The wood should extend about 1 1/4 inches above the soil surface.
Nail the forms together at their meeting points, above the soil surface.
Spread a 1-inch-thick layer of gravel inside the framework using a gardening hoe. Place the hand level on top of the gravel to check it is roughly level.
Mix ready-made concrete with water in a wheelbarrow using a shovel, following the manufacturer’s instructions. Your concrete is ready for spreading when it has the consistency of peanut butter.
Pour the wet concrete into your framework. Fill the framework approximately halfway.
Lay four rebar lengths into the wet concrete in a square shape. Make sure the square stays at least two inches away from the concrete’s edge.
Allow the rebar’s ends to overlap each other. Wrap tie wire around the rebar to connect all four junction points.
Pour the remaining concrete into the framework from the wheelbarrow until it is flush with the adjacent ground.
Strike the framework with a hammer to remove hidden air pockets. Move around the new foundation while hitting it with the hammer to evenly remove the air pockets.
Slide a hand trowel across the concrete’s surface until you have a flat and level appearance.
Allow the concrete to cure before removing the framework and placing the fountain. Consult the concrete’s instructions for curing time.
- Ask The Builder: Outdoor Fountains
- Build Eazy: How to Make a Concrete Slab
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- You may also scoop the concrete into the framework if you want more control over it.
- Clean all tools you used with the concrete after the installation to prevent hardened buildup.
- Be careful while walking around the framework. Do not trip on the wood extending out of the ground.
Writing professionally since 2010, Amy Rodriguez cultivates successful cacti, succulents, bulbs, carnivorous plants and orchids at home. With an electronics degree and more than 10 years of experience, she applies her love of gadgets to the gardening world as she continues her education through college classes and gardening activities.
Experts agree that the best temperature to pour concrete is between 50-60 °F . The necessary chemical reactions that set and strengthen concrete slow significantly below 50 °F and are almost non-existent below 40 °F . Even when daytime temperatures are within the satisfactory range, winter concrete setting creates risks that could result in weak, inadequate concrete. If nighttime temperatures are below freezing, the water in the concrete will freeze and expand, causing cracks. Additionally, if temperatures reach below 40 °F (but not freezing) during set time, concrete will take much longer to reach required strength. However, if the correct measures are taken, concrete can still be successfully placed during even the coldest months of the year.
Things to Consider with Cold Weather Concreting
Before embarking on a cold weather concrete project, it’s important to determine any special strength requirements or considerations. This will help as you schedule your pouring and determine which strategies you will use to keep your surroundings and materials warm. The predominant challenge you will face during a winter concrete project is ensuring that the concrete sets before it is exposed to freezing temperatures. You might take the following suggestions into consideration as you plan your upcoming project:
- Use heaters to thaw frozen ground, snow or ice.
- Use hot water to mix cement.
- Keep dry materials in a dry, warm location.
- Use products designed to set quickly. During cold weather, these products will not set as quickly as the instructions may indicate, but will set faster than conventional materials.
- Use additives that accelerate set time. Use caution; if additives contain calcium chloride, any rebar or metal wire mesh in concrete will rust and cause concrete to crack.
- Use extra cement (typically 100 lb/ cubic yard) to make the reaction hotter and cause concrete to hydrate more rapidly.
- Remember that you still need to wait for bleed water to evaporate. Incorporating the water into the surface during finishing will weaken the surface. Bleeding starts later and takes longer during cold weather; you can use squeegees or a vacuum to remove water quickly.
- Wait until concrete has reached desired strength to remove any framework. If the framework is removed too early, the concrete will be damaged and the surface could collapse.
Maintaining Ideal Temperature
After implementing the above suggestions, It’s important to consider how you will keep concrete at the correct temperature during the curing process. Concrete must maintain a temperature above 50 °F for approximately 48 hours for the correct chemical reactions to take place. Two popular options used during cold weather concrete curing are heated enclosures and insulated blankets. If using an enclosure, ensure that the structure is both wind and waterproof. Additionally, ensure that there is proper ventilation for the space heater. Heaters cause an increase in carbon dioxide that could cause carbonation in the surface of the concrete.
Cold Weather Concreting Imagine arriving at the job to find a fresh layer of ice and snow on your pour.
Electric concrete blankets versus insulated blankets. Which one is best and why is it Powerblanket? Not All Concrete Insulated Blankets.
Welcome To Powerblanket The Powerblanket family began our journey back in 2005. Since then, our patented, American-made temperature control products.
One thought on “ Pouring Concrete in Cold Weather: How Cold is Too Cold? ”
what would you recommend as a method for setting pole barn poles in winter? I planned on using hot water and normal bags of quick set made for posts. Today only got up to 10 above zero but it might get to 25 or 30 on the days I’m hoping to work. Do you make heat blankets that would wrap around a 4×6 green treat for a 48″ deep hole
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Things You Will Need
Local building code
Call the building inspector out to look at the footer trenches and the steel reinforcement before pouring. In areas subject to earthquakes or ground shifting, building codes may be very strict.
Wear protective eyewear, long pants and a long sleeve shirt to cover skin when pouring concrete.
Avoid digging the footer trenches any wider than you will pour the footers to reduce footer movement later.
Place rebar caps on the tops of the rebar rods that extend from the footers. The sharp ends of these rods can impale someone who falls into the pit.
A home’s foundation may be a basement, a crawl space or just a slab-on-grade. Before the contractor forms and pours the foundation, he will pour the footers to reduce future foundation movement due to soil shifting or settling. Poured directly onto the ground, the footers serve as the base that will support the rest of the foundation.
Excavate the footer trenches. The standard footer is 1 foot deep and 2 feet wide and it is directly beneath the foundation wall. In addition, footers must be below frost line to prevent foundation shifting that may occur when the soil swells and contracts from temperature changes. Your local codes will tell you how deep you must pour footers.
Add steel reinforcement to your footer trenches. Although building code determines the amount of steel reinforcement in the footers, a standard practice is to install three rebar rods, running parallel to each other, approximately 6 inches apart. Additionally,18-inch rebar rods, placed at 3-foot intervals, cross the longer rods.
Secure the long rebar rods to the shorter rods that cross at right angles with rebar ties. Place one tie beneath each “T” where the rods intersect, and bring it up on both sides, twisting it together tightly. Repeat with every intersection.
Raise the rebar off the ground with rebar chairs. These small plastic units have indentations in the tops to hold the bars. Rebar chairs raise the level of the rods a couple of inches off the ground, allowing the wet concrete to fill in around the rebar.
Pour the concrete and level the footers. Unlike concrete walls, footers rarely have exterior forms so the concrete truck dumps the wet concrete into the trenches and the workers spread it out from side to side with shovels, leveling it as they go with large hand trowels.
Insert the vertical rebar for the future basement walls or stem walls before the wet concrete sets. As soon as the concrete thickens enough to support the rods, drive each one in, by hand, near the center of the footer. The exact placement is not vital as long as the rods are within a couple inches of the center on either side. Local code may regulate the distance between rods but a standard distance is 3 feet apart.
- SolidRockExcavating.com: Poured Walls
- Express-Homes.com: Building a Home
Glenda Taylor is a contractor and a full-time writer specializing in construction writing. She also enjoys writing business and finance, food and drink and pet-related articles. Her education includes marketing and a bachelor’s degree in journalism from the University of Kansas.
Contractors and architects striving to build durable, strong, and energy-efficient foundations should consider Fox Block insulated concrete form (ICF) over poured concrete foundations. ICF and poured concrete foundations both aim to support a building and resist lateral forces and buckling. However, a high-performing foundation must also seek to resist cracking, moisture intrusion, and heat flow.
ICF foundations, like one built with Fox Blocks, more effectively resist heat flow, cracking, and moisture intrusion over poured concrete foundations.
Why a Strong Foundation is Important
A strong foundation gives a building or home integrity against the forces of nature. It also ensures a safe place to live, work, etc. A foundation supports and anchors a building. It is also a water and soil vapor barrier. Importantly, a foundation is responsible for all the load transfers from the building to the ground.
There are several foundations used in modern construction: crawlspace, slab on grade, and basement.
- Crawlspace foundations support the entire structure and are similar to basement foundations, only they are more shallow – three to four feet deep.
- Slab foundation is a concrete slab, between four and eight inches thick. Slab foundation is the least expensive of the three foundations.
- A basement foundation supports the entire structure. A basement foundation is a minimum of eight feet above the footings and provides living and storage space.
Two materials used to construct foundations are ICF and poured concrete.
Insulated Concrete Forms Foundations
ICFs provide durability and insulation for below-grade walls. Constructing ICF foundations involves dry-stacking expanded polystyrene foam panels, or interlocking hollow extruded polystyrene foam, to a foundation’s length. The forms are reinforced and braced. Workers then pour concrete into the hollow form panels. ICF foundation construction is a fast and simple method of building below-grade walls.
Advantages of ICF Foundations
- ICFs provide an excellent curing environment for concrete walls, resulting in a concrete foundation with about double the compressive strength of conventionally poured concrete foundation.
- ICF foundations are disaster-resistant. For example, Fox Blocks, with steel reinforced concrete, are disaster-resistant and can withstand tornado and hurricane winds exceeding 200 mph, and projectile debris traveling over 100 mph.
- ICF foundations incorporate continuous insulation and have few to no thermal bridges.
- ICF foundations have built-in insulation values of greater than R-20. For example, foundations built with Fox Blocks exceed ASHRAE/ANSI 90.1 energy code requirements with an R-value of 23.
- ICF walls are fire-resistant. For example, Fox Blocks have a fire-resistance rating (ASTM E119) of 4 hours for the 6-inch blocks and 2 hours for the 4-inch blocks.
- ICF is termite resistant with an application of a product like Polyguard Products, Inc. 650 XTM or 650 XTP membranes.
- The ambient temperature can be as cold as 5°F when pouring of concrete into the ICFs.
Poured Concrete Foundations
Poured concrete foundations became popular in the 1980s. Constructing a poured concrete foundation involves placing forms on top of spread footings. Then steel rebar is placed between the forms. The last step is to pour concrete into the forms. Poured concrete walls are 8-10 inches thick and available with surface patterns, like brick, which provides a finished appearance.
Advantages of Poured Concrete Foundation
- Poured concrete foundations provide a high level of strength and durability and can last for decades. Also, poured walls have a compressive and flexural strength several times that of concrete block.
- Poured concrete foundations are fire-resistant. Solid wall construction affords at least twice as much protection against fire as hollow core concrete block
- Poured concrete foundations are termite-resistant.
Disadvantages of Poured Concrete Foundation
- Poured wall concrete should not be poured in very cold weather.
- Water leakage problems in poured concrete foundations
- If not prepared correctly, poured concrete can crack, which water can leak through. These cracks are often difficult to find and require the building owner to dig up all the concrete to find the source of leakage.
- Poured concrete walls can leak moisture through non-structural cracks in the wall, where the floor and wall meet, at the top of the foundation wall or through the porous concrete.
- Leaks may occur if the foundation drops, settles, or sinks due to the soil below the foundation collapsing.
- Dry spots in the concrete wall can occur by improper grading or poorly planned outdoor construction.
Insulated Concrete Form Vs. Poured Concrete Foundations
ICF foundations are more energy efficient, less prone to moisture intrusion, less sensitive to cold temperatures than poured concrete foundations.
- ICF foundations have an R-value of greater than 20. Poured concrete foundations have R-values of less than 3.
- Because the forms protect the concrete of ICF foundations, they are less susceptible to cracking and leaking than poured concrete foundations.
- ICF foundations can be constructed most times of the year because it is not as sensitive to cold temperatures as poured concrete.
- ICF foundations have the about double compressive strength of conventionally poured concrete foundations. Therefore there is less opportunity for moisture intrusion with ICF than poured concrete.
- Poured concrete foundations are more prone to shifts in the ground and water pressure than ICF foundations. So, poured concrete foundations are more at risk of cracking and leaking, which can lead to mold and mildew growth.
ICF and poured concrete foundations both strive to support a building and resist lateral forces and buckling. However, a high-performing ICF foundation, like one built with Fox Blocks, is more energy-efficient and resistant to cracking and moisture intrusion than poured concrete foundations. Builders and architects aiming to construct durable, healthy, and energy-efficient foundations should consider Fox Block ICF construction.
We are planning a new cabin in the mountains. The existing cabin has been there almost 90 years now. The issue with building a new cabin is the footings. Is it possible with enough people to pour a concrete foundation with nothing more than a mixer and piles of ready mix? There is no way on earth a cement truck could make it to the site. There is about 9 miles of serious off-road to get there. Might be able to drag one in with a dozer but it would be dicey.
Is there any solution for the situation where cement trucks just can’t make it?
And before I get a slew of “. no inspector would ever let you. ” or “..building codes require. ” This is unincorporated land and no building permit is required. Doesn’t mean I don’t have signed drawings or don’t care about code. I’m just saying that limitations on pouring by hand that are based on legal issues are not relevant here.
Look what they did in Egypt a few millennia ago. with enough people.
How deep is the frost line?
Have you considered simply drilling, and installing pilings for the foundation?
If I were to do a remote cabin, it would not have a poured concrete foundation,,
Thanks for the fast replies! Let’s see if I can answer questions.
How deep is the frost line? Ans: This is California so frost line isn’t really a concern around here. Probably an inch at the worst ha ha. The soil condition in general is sandy/rock. You could not ask for a more stable soil. The existing cabin is sitting on a 4″ x 4″ “foundation” (using the term very loosely) and has stood for 90 years with only one crack. I will be building a larger structure however.
Have you considered drilling/pilings? Ans: Not seriously but maybe that isn’t all that bad of an idea. I’ll have to do the calcs to see how many I would need and the spacing. Digging in that rock isn’t something I would look forward to but at least it can be done with a small crew.
RedNeckRacin: I was thinking exactly on those lines. Maybe three or four mixers and I think I can get about a dozen workers. This will be a 25′ x 50′ structure. The current plan was 8″ x 16″ footing. That’s around 5 yards ish. I’ve seen those 1.75 yard towable mixers. Maybe two of those gets the job done if we can feed it fast enough.
Feel free to tell me I’m crazy. It’s happened before. :laughing:
For a perimeter footing of only 5cy, it is very doable if you can haul the equipment
and materials into the site. If you can get a tractor in there, consider a tractor-mounted
PTO mixer. I have done numerous pours of a yard or 2 without any help at all.
My Mixer80 is rated at a bit under 1/3 cy per load. Those small electric mixers are
usually rated at 1-2 cubic FEET per load.
There are also the 1 cy trailer-mounted mixers out there. Loading them is what
you need to plan for.
Instead of pouring all the walls, you could pour a footing, then stack blocks. Either dry stack and use the one of the outside bonding agents like quikcrete “quikwall”, or just use a regular mortar. Then backfill the cores if you want the extra strength. either just at corners and occasional piers along the walls (especially where joists will sit), or in every one. Depending on height, you will probably want to drop a chunk of rebar in some of those.
The biggest advantage I can see of doing this over a formed pour is that for a formed pour, you need to make up bigger batches (or set rebar, or have “keys” in your forms between sections for tying wall sections together). The smaller the batches you need to make and the less concrete you need to get in place all at once, the easier it will be, particularly for one or two people.
If you have a lot of loose stone, you can also “cheat” regular form pours some by dropping in stones until the concrete level is up to where you want it (I would probably stick to short sections of wall if I did this, like 4 or 6 feet). Had an uncle who did this while also digging out the basement by hand with a wheelbarrow. in his 80s. Dig out out, shore, form, pour, add stone, go back to digging. I think he was finding the stones as he was digging.
Sometimes you can also do a “climbing” or “rising” form, where you have the form set 1 or 2′ high, pour, let set, strip, and reset another 1 or 2 feet until you get up to the wall height you need. It’s still doing a wall in sections, but vertical rather than horizontal.
People did all of these by hand before there were concrete trucks, particularly during the post-ww2 building boom.
If you have access to gravel and sand on site, you don’t even need to bring in full blend concrete mix, you can haul in a smaller amount of portland cement and mix up your own. You can count shovels full (1 of portland, 2 of sand, 3 of stone for a basic mix) or you can make a box form about a cubic foot square (one 94# bag of portland is one cubic foot, so easy multiples like a full or half bag make counting easier). You can make a mixing surface to use with hoes and square shovels out of a couple sheets of plywood (or mix in a mortar tub or a wheelbarrow) if you can’t get a mixer and generator or gas mixer there.
Making a whole foundation from bags is a lot of work, but very doable if you break it up either by breaking the project into segments or by adding more bodies so the individual workload is still reasonable.
In this article i will take you through the various steps required to show you how to build a concrete block pillar from start to finish.
Positioning your pillars
First thing you need to do is mark out the ground where you want your pillars to be – sounds easy but there are a few things you should keep in mind.
If the pillars are close to the road side – are they back far enough to allow you to pull up in your car, so that the back of your car is in off the road?
Another thing to keep in mind is the distance apart you will make them, don’t have them too far apart and don’t have them too close.
Be aware that there may be other vehicles required to enter and exit your premises which are larger than your car – delivery lorries and oil lorries to name a few.
Usually i would keep them minimum 14 feet apart providing there isn’t too sharp a turn in.
Marking out before digging
When you have decided the width the pillar is going to be and where you will place it – the next thing you need to do is mark it out on the ground – i would advise using a line marker spray can – they are so handy.
Remember to keep the front faces of two pillars in line with each other – otherwise it will look like a mess botch job.
Mark each pillar on the ground and then make another line 6 to 12″ outside the pillar the whole way around- this is the area you will dig out to put in your foundations.
How will i dig the hole?
You can either use hand tools like a spade and shovel or use a digger to dig out the pillars – depending on how large the foundations are.
If you have never dug out pillar foundations before i would advise you use a digger as it is quite labour intensive.
How deep should pillar foundations be?
You should dig the hole for the foundations down to a depth of 2 to 3 feet deep or until you hit hard ground – you should keep the side of the foundations vertical and the hole should have four nice square edges to it.
The reason for wanting a square hole with vertical sides is the pillar foundation will be less likely to move in a neat square hole as opposed to having a rounded bottom hole.
Setting the depth of concrete
When everything is dug out and the base is level and the sides vertical and straight you should hammer in four iron rods into the base – one in each corner of the foundation.
Steel rods showing depth and level
The top of these rods will mark the depth of concrete you will be pouring in. I would recommend pouring 8 to 12″ of a concrete foundation for building on.
Keeping your foundations level
Set a 48″ spirit level across the top of the four rods and adjust them until they are level – this means when you pour you concrete into the foundation when you stop at the top of these bars your base will be at the required depth and it should also be level. This will make it much easier to build your blocks on.
Add services first
Next you can add any services the pillars require – for lights or electric gate controls. I would set a piece of plastic pipe/ducting into the foundations so that you don’t have to chisel into the base at a later stage.
Concrete foundations poured
Beginning to lay blocks
After two to three days after the concrete has been poured you can not begin to build you blocks on the base.
You should start with the front row of blocks first – using a builders line to keep both rows of blocks in line.
First row of blocks laid
Keep your pillars in line
You can then lay your back row of blocks using the builders line, which you should have set by using a tape measure from the front row to the correct distance to the back row.
Showing the pillars in line
You can then lay the sides using a set square against the front and back rows.
inside the pillar
When you have the two bottom rows laid out you can then begin to build row upon row until you get to your required height.
Pillars rising up – showing post/parcel box
What type of gate do you want?
You should know before building your pillars if they will be hung gates or freestanding pillars with sliding gates – this will allow you to add hangers into the block work as you go. I will be having a sliding gate so i do not need to build in hangers
Keep your pillars plumb
Use your spirit level against the sides as you lay each row of blocks to ensure you pillars are plumb, and keep checking they are square using your tape measure and set square.
Granite stones fitted
Before adding your pillar tops you should carry out any wiring or fixing as once the pillar top goes on it is much less convenient to work on.
Adding the pillar top
The pillar top should be fitted square to the top of the blockwork – use a tape measure to check that all sides are sitting equal distance from the blocks.
Pillar tops on the granite rings
Complete with your finish of choice
Lastly you can finish the pillar with whatever you choose – stone facing, smooth plaster or pebbledash.
These will be finished with a white marble chip inside a slurry of white cement know as a wet dash -which will stop at the the square ring of stone (granite) to be in keeping with my wifes parent home pillars next door.
The old pillars My pillars in view of the original pillars
I hope you found my article helpful – how do you think my pillars turned out? Comments below…Thank you!
If you are looking for a new home or maybe you already own your own house but would like to have a new one built there, then concrete is a great choice for you. Concrete can be used for all kinds of things from a home, to a commercial building, and also in some cases as a parking lot for your business. But for your home, if you are looking for a way to make your house more beautiful and useful, then you should look into building a concrete foundation. When you do this, you will be able to build a new home that looks like it was always on the ground that was poured over.
A concrete foundation can help you create a wonderful look for your home. By putting in a concrete foundation for your home you will be able to increase the value of your home by building on a solid foundation that will last for years. This can be done by simply hiring someone to put down the concrete for you, or you can choose to do it yourself. Either way, you will have a great-looking home that will stand the test of time.
One thing that you will want to do before you begin pouring concrete at your home is to make sure that you have all of your permits in place. Some people may not realize this, but all of the concrete that is poured has to go through a licensing process to be used. Once the concrete is poured, you will be able to apply for licenses for all of the people involved with pouring your concrete as well. This includes the people that will be putting down the concrete, as well as the contractors that will be using it. You will need to apply for permits for each contractor to ensure that they know that they are not violating any laws when they are pouring your concrete basement.
After you have all of these permits in place, then you will be ready to get started on your basement foundation. The first thing that you will want to do is make sure that you hire a qualified cement inspector to come out and inspect the area that you are about to build on. This way, you can make sure that everything is done according to code, and that you are not going to have any problems after the concrete is poured. A cement inspector will check everything from the pH level of the cement to the amount of water that has been added during the pouring of the concrete. If there is something that he notices that does not seem right, then he can tell you what it is and help you make the correct adjustments in your construction plans.
Once the cementing inspection is complete, the next step that you will have to take is to build a foundation for your concrete basement. Many people will decide that they are not going to use their basement as a storage space. Instead, they will use it as a work area for their hobbies and other activities. In this case, you will need a concrete foundation to support whatever type of activities that you have planned for your basement.
Most people will choose to use an above-ground basement foundation. This type of foundation is much easier to set up than an in-ground basement foundation. The reason that an above-ground basement foundation is easier to set up is that the weight of all of the concrete that is poured onto the soil is usually enough to keep the foundation from shaking. You should also keep in mind that an above-ground basement foundation installation will cost you more money than a basement foundation installation. The price difference between the two types of foundations is actually quite large.
Once you have chosen the kind of foundation that you want to use, you should start to pour your concrete. After your concrete starts to dry, you will notice that it will settle no matter what kind of foundation you are using. In some cases, you might have to add some concrete to make sure that the concrete stays in place. If you are not experienced with concrete basement installation, then it would probably be a good idea for you to contact a professional to get the job done properly. It would be wise to call Concrete Columbus Ohio to find out what concrete basement finishing services are available.
Concrete is one of the most popular kinds of concrete that you will see around. There are many different kinds of concrete that you can use to create beautiful basement designs. You can use a concrete basement foundation to strengthen the entire structure or you can use one of the many concrete options to spruce up the basement. No matter what option you choose, you can be confident that you will be able to create the basement of your dreams that will last for many years into the future.
Posted on July 2, 2010 by SteveP
The problem is a building inspector said if I pour the patio at 1st floor level (no step) I would be pouring against the wood sill plate and it could rot and possibly attract termites. He offered no help in resolving this issue.
6 Comments on “ How do I correctly pour a concrete patio against a house.? ”
Build a frame or insert a divider (the almost-cloth-like stuff that goes between sidewalk blocks)
Like the01animal says – expansion joint material
go to building supply and get expansion joint. that is the name and they’ll know what it is. place that against house and pour your patio.
The best thing to do and it’s the code in VA , is to put aluminum coil in between the wood and the concrete.
I would advise locating a vinyl siding company and getting them to break some scraps that they’ve laying around about an inch much higher than the concrete will be poured and as far out from the house as the scraps will go. If you are pouring 4 have them break it 5 high.
As you install the metal, shoot some silicone caulking behind it. Just nail it with roofing tacks enough to hold it until the concrete is poured. I always wait until the last thing, just before I pour the concrete because the weight of it will spread out the silicone a lot better than any other way.
If you look you should be able to find someone with a color at least close to the same color as your home. If not, go for an abstract color. Maybe a color that matches some trim on the house.
Send me an email if I can help any more.
At least give me the best answer because it’s the best you’ll get, LOL.
wow, 2 thumbs down for the best answer…i have used homosote expansion joint and i have used coil stock…coil stock is the best choice in my opinion…even if you poured against the sill plate and ran a bead of concrete caulk along the seam when it was set it would be ok…there should be enough slope that water shouldnt be that much of an issue…most inspectors dont have a clue anyway…
depends on what you’re doing…. A patio with no structure on top would only need a wooden
( treated for ground contact – green ) joint – one x 4.
If you’re adding a foundation, you may drill & epoxy rebar dowells so the ne is attached to the old & termite treat the ground where they meet. This connection may just be simple or have beams next to & under the existing foundation ( engineer will determine ) . He is right, most inspector are idiots.
Not only do you want to not make the wood rot but you also need to make any termite entry visible.
The best way is to have the slab end about one hundred mm (4 inches) back from the wood and bridge this gap for a walking surface with a metal grill like you get over a drain. Plumbing supply places will sell you these in nice lengths. That way your pest manager can both inspect simply and easily re-apply chemical without drilling the slab. AND your wood will not rot before your eyes.
Every so often, a construction team or a DIYer will come upon a problem that’s difficult to solve with conventional knowledge. One such problem involves pouring new concrete over an existing concrete structure.
On its face, this appears to be a simple enough procedure. After all, two types of concrete should be able to bond to each other easily…right?
Well, as it turns out, the process requires more foresight than that.
This guide will take you through the steps needed to accomplish this task without leaving your new concrete slab in a weakened state. To that end, this guide should effectively answer if pouring new concrete over existing concrete is even a wise construction method in the first place.
Can You Pour Concrete Over Concrete?
This is a common question among contracting teams as well as DIYers.
Both groups may be surprised to learn that you can, in fact, pouring new concrete over an existing concrete structure. Not only is it possible, but such a procedure is routinely performed in situations where an individual does not want to spend the time and money necessary to fully rip out and replace an existing concrete slab.
Instead, these individuals simply need to take certain steps (outlined below) to prepare their existing damaged slab before pouring on the new wet concrete. However, just because this can be done does not mean that it is a perfect solution to repairing concrete.
Using this method tends to have a shorter lifespan than expected, for example. That means that you’ll likely need to repeat this process before long, especially if your concrete surface in question sustains a lot of wear or pressure on a regular basis.
How to Pour Concrete Over Concrete
In either case, should you decide that this is the best way to get your job done, continue reading for step-by-step instructions.
Step 1: Prepare the Surface
To begin, you’ll need to properly prepare your existing concrete slab’s surface for a fresh application.
This can be done in several ways, including simple brushing with a broom. However, a strong scrub with a power washer is advised in order to remove any concrete sediment and shards. Ground-in dirt, sand, and leaves can also inhibit the adhesion process, so ensure any residual grim is properly lifted from the surface before proceeding.
Step 2: Prepare the Forms
Next, you’ll want to prepare your concrete molds just as you would if you were working from scratch and pouring an entirely new slab.
However, while raising your forms, be sure that their sides are fully flush with the remaining sides of your old slab. Otherwise, there’s a risk for new, wet concrete to seep into that gap and cause the slab to become uneven at that edge.
Often, the process of pouring new concrete over old concrete can cause its overall thickness to increase noticeably. As such, you may find it prudent to add a mesh or rebar structure to your new hybrid concrete slab. If you choose this route, said mesh or rebar should be placed and positioned after your forms are set.
Step 3: Apply Bonding Agent
The secret to successfully welding an old concrete slab to a new batch of concrete lies in the bonding process. However, this process won’t fully take place on its own, regardless of what kind of concrete you decide to use. Instead, you need to plan ahead and apply a specialized bonding agent prior to the application of your desired concrete mixture.
These kinds of bonding agents are commercially available and can often be mixed on-site with only water.
Once you’ve mixed up your bonding agent, you’ll want to apply it across the entirety of your existing concrete surface. This includes every gap, crevasse, and crack.
Once a full layer has been applied, you should pass back over the bonding agent’s surface with a hand trowel to create bonding channels (much as you would when preparing a bonding agent during the tile application process).
Step 4: Mix, Pour and Cure
Once you’ve properly applied your bonding agent, you’re ready to mix up your new concrete and pour it into the mold. Ideally, you should choose a similar concrete mix ratio to your old concrete slab. This will help the new and old slabs work together effectively when mitigating both lateral and horizontal pressure.
As always, be sure to follow your concrete mix’s instructions so that it comes out to proper consistency and cures as expected.
Once your concrete is poured, it’s time to let the whole hybrid structure cure. This includes allowing proper curing time for your bonding agent, which likely requires more curing time than the concrete proper.
Do not attempt to “test” your concrete until well after both drying periods have elapsed.
Mistakes to Avoid, Tips & Tricks
There are a few mistakes that you’ll want to avoid while planning for and carrying out a concrete-on-concrete project.
The first of these is forgetting to use or intentionally forgoing a bonding agent.
No matter what mix ratio you use, new concrete on its own is simply unsuited to bond to an existing concrete structure. Failing to use a bonding agent, therefore, can cause the structure to become unstable and crumble soon thereafter.
Also, while preparing to perform this type of task, some DIYers forget to account for a rise in level resulting from the stacking of two concrete layers. If you’re working on a sidewalk or driveway, this may not be a huge issue (other than introducing a potential tripping hazard). But if you end up raising the level of a concrete patio, for example, you may find yourself in a bind with regards to spacing.
If you came into this guide wondering if pouring concrete on top of concrete was even possible, your question should be effectively answered.
Not only is this process possible, but it only requires a bit of extra planning (and a quality bonding agent) to be performed properly. You know now those crucial steps, so you should be able to complete a concrete-on-concrete pour in the future when a professional or DIY job requires it.
Many buyers start building their homes in the spring. They often do this to prevent cold weather from damaging the freshly poured foundation of their home. Despite this widespread practice, many people wonder whether you can pour a concrete foundation in the winter.
Discover some ideas on the subject!
A concrete foundation that doesn’t like frost, snow and ice
There are safe and effective ways to pour a concrete foundation during the winter season. The first step is to ensure that the ground under the foundation isn’t frozen and is free of snow and ice.
Foundations are used to transfer the building’s weight load to the ground. However, during periods of frost, the soil volume increases due to ice, which affects its support capacity. When the ground is frozen, the structure is falsely supported and tends to collapse when the ice melts in the ground. Freezing also increases soil moisture levels, which hinders the development of concrete strength. To counteract these effects, your concrete expert may recommend that you protect your floor by covering it with hay or plastic sheeting.
Protecting the freshly poured concrete slab in cold weather
Concrete is very resistant to cold. Its freezing point is around -2.78°C (27°F). However, this high resistance doesn’t prevent it from freezing. As such, the concrete must be protected until it reaches 500 pounds per square inch (psi). Since some freeze-thaw cycles occur during the winter, concrete protection must continue until it reaches 1500 psi. The temperature of the concrete must therefore be maintained above its freezing point until its compressive strength is 500 psi. Formwork systems are a good way to protect concrete from cracks. They are also very useful to prevent excessive moisture loss.
Creating the mixture: the key to pouring the slab in winter
To properly pour a concrete foundation in winter, special attention must be paid to the creation of the mixture. Concrete is a mixture of water and cement. The higher the water content of the concrete, the more vulnerable the concrete is to freezing. Adding excessive amounts of water to the concrete in winter will contribute to early freezing of the foundation.
Relying on admixtures for a concrete foundation
In addition to the importance of using concrete that contains the right water/cement ratio, the use of admixtures is highly beneficial when it comes to pouring a concrete slab in the winter. Admixtures are additives that are introduced into concrete to accelerate the hydration process in order to generate greater internal heat for increased strength gains. Chloride-free accelerators are very effective additives for pouring a concrete foundation in winter.
Foundation Crack Expert: for a solid foundation, even in winter
Winter shouldn’t stop you from pouring your concrete foundation. With the right precautions, you can move forward, even in cold weather. This way, you will have the satisfaction of moving into your home in the spring, if you so choose.
Foundation Crack Expert has proven expertise. For any questions about concrete slabs, contact one of our experienced technicians.