How much does it cost to build a house foundation?

When building a new home, you must start with a foundation. The foundation is the most important part of a new build, from supporting it to holding the structure’s weight. Concrete foundations are the most common because reinforced concrete can hold any home’s weight. While most people associate foundations with homes, they can be used for many buildings and constructions, such as garages, sheds, and other outbuildings. This guide focuses mainly on concrete house foundations, with other construction types mentioned in later sections.

Concrete foundations come in many styles that may include walls, impacting the price. The national average cost to build a house foundation ranges from $7,000 to $18,000, with most homeowners paying around $9,502 for a 1,000 sq.ft. installed concrete slab foundation with a vapor barrier. This project’s low cost is $5,145 for a 600 sq.ft. slab installed. The high cost is $21,747 for a 1,050 sq.ft. installed stem wall foundation with a vapor barrier.

Concrete Foundation Cost

Concrete Foundation Cost per Square Foot

Most concrete foundations are priced by the square foot. This means that regardless of the type and having walls or only a slab, the total area is considered when pricing the foundation. There are several concrete types priced by the square foot. This includes simple slabs and complex stem wall basement foundations. The prices range from $5 to $25 a sq.ft. for foundations before factoring in excavation, vapor barriers, and potential insulations.

Concrete Foundation Cost per Linear Foot

If your home uses a concrete crawl space foundation, the concrete footings supporting the crawl space walls are poured and installed by the linear foot. While the crawl space is not made entirely from concrete and usually uses cinder block or concrete block to complete the space, the footing is poured with concrete first, and then the walls are built on top. The footings range between $10 to $15 per linear foot installed. This does not include the prices of the crawl space walls, only the price of the concrete foundation. The average concrete block wall adds another $6 to $7 per linear foot, for a total crawl space price per linear foot of $16 to $22.

Concrete Foundation Cost by Type

There are several types. Each has a specific use, depending on the finished foundation, soil type, and climate. Slab foundations are the most common in many parts of the country. These can be poured as monolithic slabs, meaning the footings and slab are poured at once or poured as stem walls, where the footings are poured first and the slab later. In other areas, crawl spaces are more common and may be done with concrete footings and block walls or as a pier and beam foundation for areas with shifting soil. If you live in an area where basements are common, you need another type, with footings and walls poured first and the center slab last. These types have different prices, depending on the thickness, footing thickness, and how much weight the it must hold. Below are the average prices for some of the most common types.

Monolithic Slab-On-Grade

A monolithic or slab-on-grade foundation ranges between $4 and $6 a sq.ft. They are the most common type for areas with no walls, where the ground does not freeze, and with stable soil. This is the most common type for garages, sheds, outbuildings, and some small homes. This is a single foundation, several inches thick, with the edges thicker than the center. It is called monolithic because it is poured at once rather than in stages like most other types. However, they cannot be used in all areas and are not meant to support a basement.

Stem Wall Foundation

The price of a stem wall foundation averages $5 to $16 a sq.ft. installed. Stem walls are sometimes called frost walls and T-shaped foundations. This type can create a crawl space or thicker slab in some areas where the ground freezes. They are also a good type if you build into a hill or uneven ground because you can create short walls with the foundation, creating a walkout in front and a short wall in the back. To create these foundations, footings are placed beneath the frost line, and the walls are added. The footing is wider than the walls, and the slab is poured last. The range in prices for this type of foundation depends on how high the walls are, how thick the footings are, and how deep you need them to go to get beneath the frost line.

Concrete Crawl Space Foundation

The price to create a concrete crawl space foundation ranges from $7 to $10 a sq.ft. This type uses a continuous concrete footer going the perimeter of the home. You can use various walls on top of the footer, including solid concrete, cinder block, and concrete block. In some instances, you can even use ICF walls on top of the concrete footings. This type does not normally have a slab bottom, but it may have a thin layer of concrete in some instances. This is a good choice if you need an earthquake-proof crawl space and want to ensure access to the area beneath your home.

Frost-Protected Shallow Foundation

The price of a frost-protected shallow foundation is $8 to $12 a sq.ft. Frost-protected foundations are similar to slab-on-grade but insulated with rigid polystyrene beneath the foundation. These may be poured at once like regular monolithic ones but work in areas where the ground freezes. In some cases, the footings may need to go deeper, below the frost line. This is one option for creating a thinner and faster slab that is less expensive than thicker Alaskan-style slab foundations. The rigid polystyrene must be at least 2” thick and properly installed for these foundations to be viable. They are most common in commercial buildings but can be used for some residential homes, particularly those with unique building challenges from the soil, climate, and location.

Alaskan Slab Foundation

The price of an Alaskan slab foundation averages $8 to $14 a sq.ft. An Alaskan slab is a thicker version of a slab-on-grade foundation. Rather than having only a shallow trench dug, these foundations may go down several feet on the perimeter at the footings. The center is thinner than the edges but is still usually thicker than a traditional slab-on-grade. These types can be used in areas where the ground freezes without worrying about the slab cracking. They are popular in northern climates where the soil and water conditions may not support a full basement or when a walkout level is desired.

Pier and Beam Foundation

The price of a pier and beam foundation ranges from $9 to $12 a sq.ft. Pier and beam foundations are an older method of creating a crawl space foundation. They are not frequently used today because they do not offer the same stability as a concrete crawl space or stem wall crawl space. A frame is made of wood or steel beams in a pier and beam foundation, and a thin concrete slab is poured over to make a space beneath. The beams are drilled into the ground to support the foundation and load. The benefit is you can spread the load out evenly rather than confining it to the perimeter. Not every soil type can support this type, so testing is important. If the soil shifts often, you have earthquake activity in the area, or high water tables, this type is not recommended. They are becoming less common, so you may find it difficult to find someone who can do the work.

Basement Foundation

The price of a basement foundation is $10 to $25 a sq.ft. These prices are for the foundation only and do not include vapor barriers, insulation, or finish work. They are created similarly to stem wall foundations, where footings are created first, then the walls are erected, and the slab is poured last. The biggest difference is the walls are much taller than in most stem wall foundations, meaning a higher price for material and labor. They are most popular in the north and east but should not be used in areas with high water tables. Depending on the soil type, some basement foundations should be backfilled for support. Doing so may increase the price.

Concrete Foundation Footings Cost

Every foundation needs footings to distribute the load. The footing type is directly tied to the kind of foundation. For example, stem wall and basement foundations have continuous footings dug and poured first, then the walls, and finally the slab. Slab-on-grade ones have a thicker edge than the center. This thicker edge is the footing that supports the load. The only case where the footing has a separate price from the foundation is in a crawl space, where the footing is priced at $10 to $15 per linear foot. Otherwise, the price is part of the foundation’s square footage price.

In general, the footings are thicker than the walls above them. Most footings start at 12” wide, and many go as wide as 20”. This is true of all types - even monolithic ones have a deep and thick footing on the perimeter, with the slab in the center being thinner.

The thickness of your footings may impact the total price. For example, a basement foundation with a 12” wide footing may be closer to $10 a sq.ft., while a basement foundation with a 20” wide footing may be closer to $25 a sq.ft.

Cost to Pour a Concrete Foundation

The price to pour a foundation is between $2 and $3 a sq.ft. for the labor. This is the typical price for the labor of pouring and troweling the concrete, forming edges with lumber, and sawing contraction joints. Excavation and delivery may have different prices. The dirt work usually adds another $1 to $2 a sq.ft. for most shallow foundations and $5 to $7 a sq.ft. for basement foundations, for a total labor price range of between $3 and $10 a sq.ft.

Labor Cost to Build a Basement Foundation

The average labor prices to build a basement foundation fall between $7 and $10 a sq.ft. This includes framing, troweling, edging, pouring, and excavation. Excavation is the most impactful, with prices averaging $5 a sq.ft. Keep in mind these prices do not include adding vapor barriers or other finishing techniques. If you need your basement backfilled, your prices can climb to $15 a sq.ft. for the additional work.

When adding a basement to an existing house, your prices for the labor can climb as high as $20 to $30 a sq.ft., with totals of $30,000 to $70,000.

Cost of Pouring a Concrete Foundation by Type of Construction

While most people think about their home when considering pouring a concrete foundation, many other buildings also have foundations. Depending on the type of building or construction project, you may have a different set of prices for the foundation than with a typical house. Below are the price ranges for various projects based on their average sizes and the most common types.

Pouring Concrete Footings for a Deck

The price to pour concrete footings for a deck ranges from $250 to $1,750 for an average of 5 footings. Several footing types can be used for a deck. Multiple factors impact the footings you use. These include the deck weight, height, location, and soil type. The deeper you dig and the more weight the footings bear, the higher your total prices. Larger decks may also need additional footings, increasing the price you may.

Pouring a Foundation for a Shed

The average price of a foundation for a shed is $600 to $900. This assumes a 150 sq.ft. shed. Your prices could be different if your shed is larger or smaller than this. A shed typically uses a shallow monolithic slab foundation. Sheds are not usually heavy enough to require larger footings. The area you build on must be cleared and leveled before pouring it. If you install it in an existing shed and the area is already level, your prices could be lower.

Addition Foundation

The price for a foundation for an addition ranges from $1,600 to $10,000. These prices assume a 400 sq.ft. addition. If your addition is larger or smaller, your prices could be different. Typically, a house addition has a similar foundation to the home. For this reason, you could have a simple monolithic slab or extend your basement. This creates a very wide range of prices for the addition. The addition’s weight and your soil type can also impact the price you pay.

Pour a Garage Foundation

The price to pour a garage foundation averages $2,304 to $3,456. These prices are for a standard 2-car garage. If your garage is larger or smaller, your prices could be different. Most garages use a type of slab-on-grade or monolithic foundation. They do not typically require stem walls or extremely wide footers. You may need to widen the footings if you build an addition above your garage and increase the structure’s weight. In this case, the prices you may could be higher.

Mobile Home Foundation

​The price of a mobile home foundation ranges from $3,000 to $18,750. This assumes an average mobile home size of 750 sq.ft. If your mobile home is larger or smaller, your prices could be different. While mobile homes were traditionally built to be moved, they can be placed on a foundation. 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 using the above techniques. The difference is mobile homes are smaller, meaning the foundation is smaller and less expensive.

Pour a Foundation for a House

The price to pour a foundation for a house averages $7,000 to $18,000. This assumes a size of roughly 1,000 sq.ft. Your prices could be different if you are pouring a larger or smaller one. Houses can have many types, from slab-on-grade to full basements. Typically, they change geographically. For example, concrete crawl spaces are common in the south and west, while full basements are more common in the north and east. The soil’s freeze depth, type, and whether your area is prone to disasters like earthquakes dictate the type. This determines the final price you pay.

Foundation Excavation Cost

Excavation and dirt work make up the biggest parts of the foundation building. Every type needs some excavation or soil work, even if it is only grading an existing site for a slab. Excavation prices start at $2 to $3 a sq.ft. for a slab foundation and around $5 to $7 a sq.ft. for a full basement foundation. Prices can be higher, depending on the depth and soil condition. For example, if blasting is needed, prices are higher than if the soil is easily removed. If you need your basement walls backfilled, your prices for excavation are even higher - closer to $10 a sq.ft. or more, depending on the depth.

Soil Testing for a Foundation Construction Cost

The soil your foundation is built on must hold and support the load. No matter which style you build, it has footings that evenly distribute the weight over the soil. Soil that is too soft, has too much hydrogen, or holds too much moisture like clay can mean your final foundation is unstable. This is why soil testing is always conducted before building the foundation.

Soil testing happens at several points. The soil must be heavily compacted, so the removed soil is tested when the foundation is excavated. The areas where the footings are laid are compacted and tested for strength. Clay-based soils are sometimes removed, and the area beneath is backfilled with another material and compacted. Pea gravel is generally added to the soil for drainage, so testing tells you how much gravel is necessary.

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

Foundation Replacement Price

Foundations are made of concrete, and while they are strong, they may not last forever. This is why you should inspect yours regularly to look for signs of damage or settling, such as cracks. If you notice these signs, pursue repairs immediately, or 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 than to replace the old one entirely. For this reason, replacement prices have a wide range from $20,000 to $100,000. This range is due to many factors, including the foundation size and type, problem type, and the fact the home must be lifted off the foundation during replacement. The home size and shape, how far it must be lifted, and how long it must be supported determine your final replacement price.

If you need to lift your existing home to replace the foundation, expect total prices of between $30,000 and $70,000. Your prices could be higher if your home needs more extensive work to stabilize the foundation.

Planning and Permit Prices

A new foundation is part of the overall build for a new home or structure. It is added to the permit that must be pulled before new construction can begin. This involves submitting the plans for the project to your town or city hall, including the foundation. Most permits for a new house build range between $1,000 and $2,000, depending on the project scope. You can speak to your builder or town or city hall representatives for more specific information on what may be required.

​​Shallow vs Deep Foundations

The deeper you dig for your foundation, the higher the prices. Most of the labor involved is in the soil work, meaning the digging, compacting, and readying the site becomes more intensive the deeper the dig. For example, a shallow foundation may only be $2 a sq.ft. to dig, while a very deep foundation may be as much as $7 a sq.ft. That is why basements are more expensivethan crawl spaces, which are more expensive than slab-style foundations.

A deep foundation also requires more structure during the pour, accounting for additional labor. Depending on the soil, some deep ones may also require backfilling, increasing prices.

The type is likely dictated by your location and regional preferences, soil type, frost levels, groundwater levels, and home type.

Slab Foundation vs Crawl Space

If you are not going to have a full basement for your home, you still have a few options for your foundation. The most common are slab foundations and crawl spaces. Both have different options and choices for how they are constructed. Slabs may be monolithic, have stem walls, be frost-proof, or be thick Alaskan-style. Crawl spaces can be created with concrete footings and walls, stem walls, or old-fashioned pier and beam. The choice is dictated by several factors, including your region, soil type, and home size and weight. Homes built in earthquake-prone areas are more likely to have concrete crawl spaces, which offer more support. A slab may be the best choice if you want your home to walk out from the ground level. Your contractor can help choose the correct type for your home based on these and other factors. Slabs are generally less expensive than crawl spaces, but there is overlap, and prices tend to even out, depending on each type.

Enhancement and Improvement Costs

Foundation Drainage

All foundations have drainage, including gravel and weep tiles. Water around your foundation can lead to structural problems, so good drainage is key. In some cases, a French drain can be added to help with additional drainage. These range between $2,800 and $6,500.

Insulation

If you opt for a frost-free foundation, your concrete is insulated during the process. If you have a basement foundation, you may also opt to insulate the interior walls using special rigid insulation designed for this purpose. Basement insulation is tied to lower energy bills for many homes, making this a good choice. In general, this type of insulation ranges between $2 and $3 a sq.ft. for 2” thick rigid foam insulation.

Home Inspection

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

Vapor Barrier

Many foundations require a vapor barrier to reduce moisture. This can limit and prevent mold and help it last longer. Vapor barriers may be added below foundations or inside or outside the walls. Their price is roughly $2 to $3 a sq.ft.

Additional Considerations and Costs

• Foundation depth. The deeper it is, the higher the prices. Very deep foundations can be much more expensive than slab ones. Going below the frost line protects it from freeze/thaw damage in cold climates but increases the project price.
• Concrete pouring. Ideally, concrete should not be poured in temperatures lower than 40º F degrees or higher than 90º F. This ensures it cures properly. A typical foundation takes about 2 to 3 weeks to cure.
• Utilities and HVAC. In some cases, slab foundations may contain pipes, wiring, and HVAC. If this is the case, repairs to these areas can be more expensive.
• Finishing. The last step of any concrete job is finishing the pour, which includes vibrating the wet concrete to remove bubbles, and then buffing and smoothing the damp concrete. This is usually done by hand and included in your foundation prices.