How Much Does It Cost to Build a House Foundation?

Whether you are building a new home or a home addition, you must start with a foundation. The foundation is the most important part of a new build, from supporting it to holding the weight of the structure above. Concrete foundations are the most common because reinforced concrete is strong and stable enough to hold the weight of any home.

Concrete foundations come in many styles that may or may not include walls, which impacts the cost. The average cost to build a house foundation ranges from $5,000 to $18,000, with most people paying around $11,000 for a 1,000-square-foot slab foundation ¹.

Costs to Build a Concrete House Foundation

Concrete Foundation Types

There are several types of concrete foundations. Each has its own specific use, depending on the finished foundation, soil type, and climate:

Foundation Cost Per Square Foot

Slab on Grade Cost

Slab-on-grade foundations are the most common type for areas with no walls. This is a single foundation, several inches thick, with the edges thicker than the center. This is used where the ground does not freeze and is sometimes called a monolithic foundation because it is poured at one time. These are the simplest and fastest foundations to pour, costing between $6 and $12 a square foot on average. They cannot be used in all areas, however, and are not meant for supporting a basement.

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Frost Protected Shallow Foundation Cost

Frost-protected ¹ foundations are similar to slab-on-grade except they are insulated with rigid polystyrene beneath the foundation. These are also poured at the same time but can be used in areas where the ground freezes. They cost slightly more than a slab-on-grade foundation, starting at around $8 and rising to $14 a square foot on average.

Stem Wall Foundation Cost

Stem-wall or T-shaped ¹ foundations are the most common and are used when creating a foundation that will have walls, such as a basement. Footings are placed beneath the frost line, and then the walls are added - the footing will be wider than the walls. The slab is poured last. These foundations are the most expensive to build because they must be poured in three separate parts, with each curing individually. If you want a basement, then this will be the concrete foundation you want. T-shaped  foundations cost around $16 to $18 a square foot to pour.

Pier and Beam Foundation Cost

Use pier and beam foundations to create a crawl space. The frame is made of wood or steel beams, and then a thin concrete slab is poured over the frame so that there is a space beneath the concrete. The beams are drilled into the ground to support the foundation and the load above. Not every soil type can support this type of foundation, so testing is important. These foundations are becoming less common, so you may also find it difficult to find someone who can do the work. They are more expensive, starting at $18 a square foot, increasing depending on whether you use wood or steel and how far they must be drilled.

Labor Costs to Build a House Foundation

Varying labor costs go into building a foundation. Excavation, delivery, pouring, and compacting all have a range of prices. The dirt work comprises most of the labor costs. For a typical slab foundation pour, the labor is around $3,000 out of the $11,000 total. For a basement foundation, expect labor to cost closer to $7,000 out of a $16,000 total due to the additional time needed to pour the foundation in three separate steps, along with the added work to construct the walls.

Building Process

The building process to create a foundation varies depending on the type of foundation you are putting in, but many of the steps are the same. To receive a permit, submit your plans for the entire build. The foundation does not need a separate permit.

The soil is tested, and excavation begins. When pouring a full basement, the footings will be put in first, examined, the walls poured, followed by the slab. When pouring a monolithic slab, gravel is put down for drainage, and the entire slab is poured at once.

The concrete needs anywhere from 1 to 14 days to cure, depending on the weather and conditions. If you have a basement, it will be waterproofed, and then pea gravel and drainage tiles are installed before the rest of the building work proceeds.

Cost of Excavation for Foundation

Foundation Replacement Cost

Foundations are made of concrete, and while they are strong, they may not last forever. This is why you should inspect your foundation regularly to look for signs of damage or settling, such as cracks. If you notice these signs, make sure you pursue repairs right away, otherwise these issues could continue to grow, eventually resulting in the need to replace your foundation.

It is much easier to pour a new foundation and build on top of it than it is to replace the foundation on an existing home. For this reason, replacement costs have a very wide range of $20,000 to $100,000. This range can be due to many different factors including the size and type of your foundation, the cause of the problem - soil problems or structural problems with the home for example - and the fact that the home will need to be lifted off the foundation during replacement. The size and shape of the home and how far it must be lifted and how long it must be supported will all go into determining your final replacement cost.

Foundation Repair Cost

If you can catch foundation issues while they’re still minor, it is entirely possible to repair many of them. Minor cracks that are not due to structural problems can often be filled for around $500. If you have more extensive issues, however, your costs can be much higher, particularly if your home needs to be jacked up to make the repairs. Most people end up paying around $5,000 for their foundation repairs all together, which is significantly less than a full replacement.

Soil Test Cost

The soil your foundation is built on needs to hold the load and support it. No matter which foundation style you build, it will have footings that evenly distribute the weight over the soil. Soil that is too soft, has too much hydrogen in it, or holds too much moisture like clay can mean that your final foundation is not stable. This is why soil testing ³ is always conducted before building the foundation.

Soil testing happens at several points. The soil the foundation is on must be heavily compacted, so when the foundation is being excavated, the removed soil is tested to see how it will handle the load. The areas where the footings will be laid is compacted and tested for strength. Sometimes, clay-based soils are removed, and the area beneath the foundation is backfilled with another material and then compacted. Pea gravel is generally added to the soil for drainage, so testing enables you to determine exactly how much gravel is necessary.

If the soil is very soft in places, the type of foundation or orientation may be changed to span the soft areas and distribute the load over the compacted spaces. Soil testing ³ costs around $1,200 on average for all the tests necessary for most foundations. If you have extensive issues, however, prices can go as high as $5,000.

House Lifting Cost

Building a foundation for a new home is always easier and less expensive than raising an existing home to build a basement. Excavating the ground, testing the soil, and pouring the basement foundation is faster and easier on an empty site. Raising the home requires additional equipment to hold it in place, while the foundation is dug and poured, which adds to the cost of the project.

Raising a home to build a foundation costs around $35,000 on average. However, if the rest of the house is structurally sound, then this cost is lower than demolishing the home and rebuilding it with a basement.

Concrete Footing Cost

Every foundation needs footings to distribute the load. The type of footing is directly tied to the kind of foundation. For example, T-shaped foundations have footings dug and poured first, then the walls, and finally the slab. Slab-on-grade foundations have a thicker edge than the center. This thicker edge is the footing that helps support the load. The cost of pouring the footings is between $3 and $5 a square foot, and in the case of T-shaped foundations, they must be inspected before the rest of the foundation can be poured.

Shallow vs Deep Foundations

The deeper you dig for your foundation, the higher the costs. Most of the labor involved is in the soil work, which means that digging, compacting, and readying the site for the pour becomes more intensive the deeper the dig. That is why basements and crawlspaces tend to cost considerably more than slab-style basements. Slabs can be poured with minimal excavation, while basements require more work. The deeper you go, the longer the process and the more expensive the final foundation.

Slab Foundation vs Crawl Space

Many people choose slab foundations for their homes, but this is not the only option. If you are choosing not to have a full basement, another option is to have a foundation crawl space. Crawl spaces work well on sloped lots, while slabs need to be level. Crawl spaces can also work well in earthquake prone areas and are less prone to cracks. They are more expensive however, around $10,000 - $25,000 on average as opposed to $7,500 to $12,000 for the same size footprint. They also aren’t as energy efficient as slabs, although they do give you different opportunities and access for utilities. They also elevate the entrance to the home, which can make them more challenging to enter for the mobility impaired.

Mobile Home Foundation Cost

​While mobile homes were traditionally built to be moved, they can be placed on a foundation. In fact, they can be placed on any of the foundations that hold a traditional home, meaning they can have a crawl space, basement, or slab foundation 1 using any of the above techniques. The difference is generally that mobile homes tend to be smaller, which means that the foundation will be smaller and less expensive to build. With an average square footage of around 750sq.ft. this would make a slab foundation around $4,500 - $9,000 on average.

Garage Foundation Cost

All garages will need a slab foundation as their base. As garages tend to come in different sizes, this can lead to a range of foundation costs.

Planning and Permit Prices

A new foundation is part of the overall build for a new home or structure. It is therefore added to the permit that must be pulled before new construction can begin. This will involve submitting the plans for the entire project, including the foundation, to your town or city hall in order to get the permit. Most permits for a job of this size have costs around $1,000 or more depending on the scope of the project. You can speak to your builder or to your town or city hall representatives to get more specific information about what may be required in your area.

Enhancement and Improvement Costs

Radiant Heating

If you want hydro radiant heating installed in your home and have either a slab foundation or finished basement, this is a good time to have the pipes laid. Hydro radiant heating adds about $20,000 to the total cost of the project.

Foundation Drainage

All foundations have at least some drainage, including gravel and weep tiles. If you want additional draining, such as a French drain, this adds up to $5,000.

Basement Addition

Many people finish their basements to create more living area for the home. This basement addition costs between $25,000 and $55,000.

Insulation

If you opt for a frost-free foundation, your concrete will be insulated during the process. If you choose to have a basement foundation, you may also opt to insulate the interior walls using special rigid insulation designed just for this purpose. It adds around $5,000 to the job.

Home Inspection Cost

Your foundation will be inspected at several points in the job. The footings will be inspected before the rest of the foundation can be poured, and the entire foundation will also be inspected prior to building. This is done to ensure that the foundation is secure and has no weaknesses. Typical inspection fees range from $500 to $1,000 if not already included in the total.

Additional Considerations and Costs

• The deeper your foundation, the higher the costs. Very deep foundations may be as much as 75% more expensive than slab foundations. Going below the frost line helps protect your foundation from freeze/thaw damage in cold climates but increases the cost of the project.
• Ideally, concrete should not be poured in temperatures that are lower than 40ºF degrees or higher than 90ºF. A typical foundation takes about 2 to 3 weeks for curing.
• Pipes, wiring, and heating ductwork are included in the foundation of slab houses, which can limit access after the home is built. This can increase repair costs in the future.
• The last step of any concrete job is finishing the pour, which includes vibrating the wet concrete to remove any bubbles, followed by buffing and smoothing the damp concrete. This is included in your foundation costs.

Remodeling Terms Cheat Sheet

¹ Frost-protected: (Also known as T-shaped, Slab foundation) A layer of concrete, poured over a prepared surface of soil or gravel, that supports a house or other building structure

³ Soil testing: Chemical analysis kit used to assess soil pH, and sometimes soil nutrients, for the purpose of making fertilizer recommendations (type, quantity, and frequency)