House Foundation Costs Per Square Foot

* Based on the average foundation size of 1,300 square feet.

Concrete Foundation Cost

Concrete foundations cost $5,200 to $30,000. Foundations fall into one of two categories: deep or shallow. A shallow design reaches only about three feet into the soil. Concrete pads extend below the high frost line, transferring load from the walls to the earth. Some post and pier, slab-on-grade and concrete runners fall in this category.

You’ll use a deep foundation in areas with poor soil quality or with deep frost lines. You may also use it on hillsides, floodplains and near lakes. Deep types, like basements and piles, cost more than shallow varieties. They require more materials, excavation and labor.

Slab Foundation Cost

A concrete slab foundation costs most homeowners $5,200 to $13,000. They come in two main varieties: monolithic or stem wall. The type usually depends on the climate.

Monolithic Slab

Monolithic slab installation costs $5,200 to $13,000 on average. The whole slab and footings of poured concrete are built all at once. This makes for a fast process and lower labor costs. You’ll find these in warmer locations where the ground doesn’t freeze. Slab alone works only in areas where the surface dirt can support the house load. They’re also found in rocky areas, where excavation becomes cost prohibitive.

Stem Wall

A stem wall foundation installation costs $7,000 to $21,000 total. You’ll pay $45 to $55 per linear foot for the stem wall alone. These require more labor, excavation and materials. Installation involves a poured concrete slab, the foundation/stem walls, and footings (concrete pads) which extend into the ground beneath the walls. The walls and footings give it a higher resistance to soil changes, making it a better choice for cold climates.

Pier & Beam Foundation Cost

Pier and beam foundations, also called post and pier, cost $8,000 to $15,000 or $6 to $12 per square foot. They were the most common type of foundation before home builders started installing slab-on-grade foundations in the 1960s. Pier and beam consists of piers and posts that support multiple horizontal beams.

Although rare, you may want this kind of foundation for very particular reasons.

• More affordable maintenance and repairs: It elevates the home and creates enough space for homeowners to easily access important components, like plumbing. But stem walls do the same thing.
• Floods & Mold: Elevation also keeps the house lifted away from moisture for flood-prone areas. They also provide excellent airflow, keeping mold from growing.

Concrete Foundation Piers Cost

Piers cost about $1,000 each. Short and wide supporting blocks made from concrete or other masonry materials. Driven or poured into the ground, they hold the weight of the housing structure. Often used in stiff clay or rocky ground.

Grade Beam Costs

Made of wood or steel, these run horizontally along the bottom of the structure.

• Steel beams cost: $1,500-$5,000.
• Wood beams cost: $1,000-$3,000.

Cement or Cinder Block Foundation Cost

A cinder block foundation costs $11,500 to $15,500 on average for stem wall or pier and posts using cinder blocks. You can use cinder blocks for a variety of foundation styles, including full basements, crawlspaces, stem walls and piers.

Pile Foundation Prices

Installing piles costs $20 to $60 per linear foot of pile with a minimum cost of $28,000. That price includes labor, equipment and materials. Steel costs 25% to 35% less than prestressed concrete. Although the terms often get used interchangeably with “piers” they serve a different purpose. Piles underpin various foundation types, bypassing poor soil to bedrock when the soil isn’t good enough to build directly upon.

Piles aren’t a standalone foundation, so add the following prices to other foundation types.

You’ll use piles for extra reinforcement in the soil. This is especially true in loose soil or where you can’t easily reach higher-bearing-capacity soil. You can also use piles to repair bowed or sagging foundations. Your pro does this by driving them next to the existing walls and tying them together.

Driven deep in the earth, piles transfer the weight of the foundation past the poor soil to solid bedrock. You can use them under a slab foundation or under pier and beam foundations. Always enlist a structural engineer’s help for pile foundations.

Crawl Space Foundation Cost

Crawlspace foundations cost $5 to $16 per square foot, or $7,000 to $21,000 on average. Crawlspaces use a combination of a stem wall and often post and piers. Many also have finished slab floors.

Crawl spaces provide the same ease of access as pier and beam. If unventilated, they can harbor moisture and promote mold growth. There are several ways to combat this, including insulation and vapor barriers, which you should consider during planning.

• Insulation costs $1,400-$2,300.
• Vapor barriers cost $0.05-$1.50 per square foot.
• Dehumidifiers cost $800-$1,000.
• Crawl space to basement conversions costs $60,000-$150,000.
• Sump pump installation costs $650-$1,900.

You should almost always allow unconditioned air to ventilate the space to keep it from growing mold and mildew. Many also have sump pumps, lighting and vapor barriers. Some state codes require vapor barriers.

Like the pier and beam style, these elevate the house and can help protect against water damage in rainy climates. Their foundation (or stem) walls extend above the ground at a minimum of 18 inches and support the structure.

Basement Foundation Cost

Installing a basement costs $10,000 to $175,000 depending on whether you finish it or not. While usually the most expensive option, they may also provide greatest return on investment.

A basement beats an addition as one of the most affordable ways to add storage or living space. Commonly installed in cold areas where builders already need to install the footings deep into the ground below the frost line.

Cost to Build a Basement Per Square Foot

Building a basement foundation averages $10 to $100 per square foot. Price depends on land conditions and whether you opt for a finished or an unfinished space. It’s most cost-effective to finish it during initial construction. But the price difference to push finishing to a later date is minor.

• Unfinished basement install costs $10-$25 per square foot.
• Finished basements cost between $30-$100 per square foot.
• Refinishing your basement costs about $6,500-$18,500.

Walkout Basement Costs

Installing a walkout basement door costs $2,500 to $10,000 pushing your project closer to $100 per square foot. But it opens your basement for a future rental unit. With rental income, you can make back your investment in 2 to 5 years. For a rental, you’ll need to install a few other items to meet code requirements. You can wrap these up in basement remodeling costs of $10,000 to $30,000 or split them up as follows:

• Kitchen installation costs $5,000-$45,000.
• Egress window costs $500-$2,000.

Walk-out spaces have an outside entrance. Standard basements only have interior access. If you are building into a hill, you can build a daylit basement that features an exposed wall or walls.

Average Cost to Build or Pour a Foundation

For labor alone, you’ll spend $3,000 to $16,000 or 40% to 60% of the total foundation pour price. Labor prices vary a bit by region too. You’ll spend more in high cost-of-living areas with higher wages. Material prices tend to stay nearly the same from place to place.

Cost to Lay a Foundation for a New House

Installing a basement for new construction costs $18,000 to $30,000, on average. Some of the most significant expenses in the process come from:

• Excavation and grading
• Soil quality
• Regional pricing
• Tree removal costs

Materials contribute to budget fluctuations.

• Cinder block walls cost less than poured concrete, but aren’t as durable.
• Higher quality drainage systems can raise your initial estimate, but they could save you money on future repairs.
• Other material factors include insulation, sealers and waterproofing.

Addition Foundation Prices

Adding a foundation addition costs anywhere from $5 to $35 per square foot. It all depends on what you’re installing. The costs remain the same as a new building.

Average Cost to Build a Foundation Under an Existing House

The average cost for building a foundation under an existing house changes based on your circumstances and the type of foundation you want. For example:

• Installing a slab under a crawlspace costs $5,000-$10.000. There’s no need to jack the house up to put anything under it.
• Installing a full basement costs $30,000-$70,000. You’ll need to raise the house, brace it, dig underneath, set forms and pour. Finally, you’ll have to set your house back on the foundation.
• Pouring a slab under a raised structure comes in somewhere in the middle, or $10,000-$40,000.

Cost to Build a Basement Under a House

The average cost of raising a house and adding an extra level is $30,000 to $70,000. Raising a house costs $3,000 to $9,200. Adding a basement to an existing home can be a lucrative investment, raising your property value and likely providing a stronger and more durable foundation than before. But your budget can run more than $100,000 depending on a few factors, including:

• Soil condition
• Access to the site
• Level of excavation required
• Type of foundation you pick

Garage Foundation Cost

Concrete shed foundations and garage slabs cost $1,500 to $5,000.Building a garage costs anywhere between $17,000 and $39,000, including the foundation. Attached garages cost less to build than detached ones. Concrete slabs cost $3 to $5 per square foot.

Foundation Installation Cost Factors

Several factors demand more out of your budget. These include the price of extra materials, labor, excavation, grading, and your style and finishing choices.

The above estimates reflect costs using basic concrete. Excavation rates tally both labor and equipment. You’ll spend $100 to $245 per hour for excavation. Pros usually bill equipment rates as a flat fee per day at $150 to $250. Other elements will come into play such as the type and finish of your concrete foundation.

Foundation Inspection Cost

Foundation inspections cost $300 to $600. Inspections save you from unexpected issues and expenses. Expert structural engineers spot weaknesses and potential failures.

Aside from location and size, a unique contributing factor in the overall cost of an inspection is the experience level of the engineer. More experienced engineers charge substantially higher rates than those new to the trade.

Planning

Laying a foundation requires a plan. You must adhere to local building codes and have inspections from the city or county while you build. It is important to follow local codes and get the correct permits in advance.

• Architect fees: $2,000-$10,000.
• Building permits cost $500-$2,000 or $0.89 per square foot on average.
• Soil construction reports cost $800-$5,000. Get a full geotechnical report. Soil composition and capacity play a big part in determining which type of foundation you need.

Drainage & Heat Radiation

Factoring in radiant heat and drainage will add to your project estimate.

• Radiant floor heating costs $3 per square foot, with typical homeowners paying $6,000-$14,000.
• Drainage features cost an additional $3,000 on average.

Plan these upgrades in advance. It’s far cheaper to install these during construction than later. Your pro needs to place drainage pipes and hydronic radiant heat tubes before pouring your concrete slab. You can install newer electric radiant heating later for the same price.

Sealing & Retrofitting Costs

Sealing or waterproofing concrete costs $2,000 to $6,000. In general, concrete sealants add $0.50 per square foot for the materials.

• Sealing: $3-$9 per square foot.
• Full waterproofing: $5-$10 per square foot.

Not all basements need sealant, but it helps to avoid future repairs. Commonly, homeowners with water damage to the foundation face $3,000 or more in repair costs. Extreme damage can lead to complete rebuilds.

Spray or roll on sealers prevent moisture and vapor from rising through the porous concrete. Some help strengthen concrete and prevent cracks over time. Sealers can also prevent radon gas seepage and inhibit the growth of mildew or molds. Asking your professional to add a sealant during construction adds relatively little to the cost, compared to the benefits it will give you.

Modular or Mobile Home Foundation Costs

Foundation building for mobile homes can cost anywhere from $1,000 to $25,000. However, most cities and states have specific codes for mobile homes that limit foundation types.

• Floating slab: $6,000-$15,000. One of the best options for colder climates. Uses 6-inch slab of concrete reinforced with rebar.
• Pier and beam: $1,000-$2,000. This type performs well in mild climates and supports the house by way of cinderblocks. Not useful in earthquake prone areas.
• Block and footing: $2,500-$4,000. Upgraded pier and beam foundation, which features concrete footings for extra stability.

Basements for Manufactured Home

Manufactured and modular home basements cost $12,000 to $25,000. These are full basements, just usually slightly smaller. It’s often slightly less expensive than a stick-built home because of the smaller size.

Concrete Runners for Mobile Homes

Concrete runners cost $2,000 to $5,000. They’re mostly for manufactured homes. Runners are simply poured concrete footings all joined. They provide a stable surface for manufactured homes to sit on.

Foundation Replacement Cost

A full foundation replacement costs $20,000 to $100,000. If you see signs of damage or settling, such as cracks, it is important to pursue repairs right away. Foundation repairs cost an average between $500 and $13,000 with typical homeowners spending around $4,500.

Structural Report

Hiring an engineer costs $500 for a home structural report. They’ll correctly assess the situation and make recommendations for repairs. Structural engineers help answer some important questions that affect your budget, including:

• Can your home withstand the pressure of being raised?
• What type of materials would work best in your environment?

Cost to Lift and Rebuild or Replace a Foundation

It’ll cost $24,500 to $115,000 to raise and replace your foundation. You’ll need to budget for the following three parts of the project.

• Raising your house costs $3,000-$9,200. If soil, accessibility and foundation conditions are poor, it will take more time and equipment.
• Excavating costs $1,500-$6,000. Soil conditions affect the overall price.
• Rebuilding runs $20,000-$100,000. Price ranges reflect the type of foundation you choose to install.

DIY vs. Hiring for Foundation Work

Hire expert contractors to make sure such factors as slopes and drainage are handled correctly. Professionals will have the right equipment to excavate your property, grade the soil, as well as pour and finish the concrete. You don’t want to DIY this project. Hire a local general contractor to oversee the project or find a foundation installation company near you.

FAQs

How much does a stilt foundation cost?

Stilt foundations, also known as piling a home, cost $250 to $350 per square foot.

How much does a slab vs. basement cost?

A slab costs $4 to $16 per square foot vs. a basement at $10 to $25 per square foot.

How much is the cost of an ICF foundation vs. traditional concrete?

Insulated concrete forms cost $7 per square foot on average or slightly less than traditional concrete forms. It lessens the time spent on form setup and there’s no teardown. The insulation simply stays in place.

Is a walkout basement cheaper to build?

A walkout basement isn’t usually cheaper to build than one without a walkout. But it depends heavily on your land. If building on a hill, it makes sense. But for a walkout on flat land, you’d need to install stairs or clear the land.

How much does it cost to build a basement in California?

In California, you’ll pay $10,000 to $30,000 on average to build a basement.

How much does it cost to pour concrete in a crawl space?

It’ll cost you $5 to $10 to pour concrete into a crawlspace, including finishing work.

How much are metal building foundation cost estimates?

Metal building foundation cost estimates range like garages and other outbuildings or $1,000 to $5,000.