How Much Does a Foundation or Basement Cost?

House Foundation Costs Per Square Foot

Monolithic Slab

Monolithic slab installation costs $7,000 to $20,000 on average. It averages $5 to $12 per square foot but can reach $16 per square foot for multi-story homes, depending on the thickness and how much reinforcement is needed. Contractors often pour the footings and slab at once, making it a fast process with lower labor costs. 

Generally, contractors will use monolithic slabs to ensure thicker, sturdier reinforcement for load-bearing walls and perimeter areas rather than using footers. Builders may use monolithic slabs on level ground to ensure a more densely compacted pour.

Stem Wall

A stem wall foundation installation costs $8,000 to $24,000 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.

Contractors often use stem walls on sloped lots because they can accommodate different heights to fit the terrain. Builders can increase or decrease the free-board distance between the slab and ground to deliver taller or shorter build heights. Stem walls are stabler when coupled with fill dirt, often making it a solid choice for builds on tricky terrain. 

Pier and Beam With Crawl Space

Pier and beam foundations (or post and pier) cost $9,000 to $17,500 or $7 to $14 per square foot. You’ll pay between $500 to $2,000 per pier. Pier and beam consist of piers and posts that support multiple horizontal beams. This type of system creates a crawl space to house electrical, plumbing, and HVAC with easy maintenance access.

Pier and beam foundations work well in earthquake-prone areas, as they can accommodate more ground shift than other types of foundations. Their flexibility means less damage from earthquakes and the crawl space offers easier repairs from the potentially relatively minor damage an earthquake can cause, depending on its magnitude and the home’s condition. 

Crawl Space

Foundations with a crawl space cost $6 to $18 per square foot or $8,000 to $24,000 on average. Both stem and wall and post and pier create a crawlspace. It’s not a type of foundation but rather a space created by other types of foundations. They can have finished floors with slap or simply use gravel or dirt.

Homeowners often prefer crawlspaces to install and run piping, wiring, and ducting. Some crawl spaces offer enough room to hold an HVAC unit or water heater. Contractors often prefer them because they provide easy access to the pipes, wiring, and ducting to make repairs. 

If unventilated, they can harbor moisture and promote mold growth. There are several ways to combat this—like insulation and vapor barriers—to consider during planning. Measures for preventing potential moisture issues include:

• Insulation costs $1–$5 per square foot

• Vapor barriers cost $0.50–$0.70 per square foot

• Dehumidifiers cost $1,300–$2,800

• Crawl space to basement conversions costs $60,000–$150,000

• Sump pump installation costs $650–$2,050

Cement or Cinder Block

A cinder block foundation costs $9 to $15 per square foot or $11,500 to $19,000 on average. You can use cinder blocks for a variety of foundation styles, including full basements, crawlspaces, stem walls, and piers.

Cinder blocks make fine foundations when reinforced with steel rebar and filled with mortar. The combination of this reinforcement and cinder blocks’ compressive strength make them a solid choice in many environments. However, blocks are more leak prone than slabs; homes in wetter environments must take precautions to reduce the chance of water damage. 

Basement Foundation Cost

Labor Costs to Build a Foundation

For labor alone, you’ll spend $4,500 to $18,500 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.

Cost to Build a Basement Under a House

Installing a basement under an existing house varies in price depending on what you’re looking to add. For example:

• Crawl space with slab: Installing a slab under a crawl space costs $5,000–$15,000. There’s no need to jack the house up to put anything under it.

• Full basement: 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.

• House raising: The cost to raise a house is $3,200 to $9,900.

• Slab: Pouring a slab under a raised structure comes in somewhere in the middle or $10,000–$40,000.

Other Foundation Costs

Other foundation costs range from $500 to $39,000 for modular and mobile homes and garages. Most of the price comes from the type of installation and how thick and reinforced it needs to be. 

Garage

Concrete shed foundations and garage slabs cost $2,000 to $7,000. 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 $5 to $10 per square foot for the thinner slabs needed for these structures.

Modular & Mobile Homes

Mobile home foundations cost $7,000 on average but range from $3,500 to $25,000. Mobile home-specific codes may vary across cities and states, limiting foundation types. Here are some common options:

• Floating slab: $6,000–$15,000

• Pier and beam: $500–$1,000 per pier

• Block and footing: $3,500–$15,000

• Manufactured and modular home basements: $12,000–$25,000

• Concrete runners: $2,000–$5,000

Foundation Installation Cost Factors

Even with a poured slab and basement, you’ll need to consider a few other factors that influence your budget, such as inspections, permits, soil composition, engineering, and extra excavation costs. 

Foundation Inspection 

Foundation inspections cost $300 to $600. Expert structural engineers spot weaknesses and potential failures. They’re excellent to employ when repairing a foundation, installing one under an existing structure, or after your contractor has finished the project. As part of the permitting process, most locations require a basement to pass inspection before work can continue.

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. Anticipated planning costs are likely to include:

• Architect fees run around $2,000–$10,000

• Building permits cost $450–$2,300 or $1 per sq. ft. on average

• Soil construction reports range from $800–$5,000. You’ll want to obtain a full geotechnical report because 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 $6–$20 per sq. ft.

• Drainage features cost an additional $4,100 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 and Retrofitting 

Sealing or waterproofing concrete costs $2,300 to $7,300. In general, concrete sealants add $0.50 per square foot for the materials.

• Sealing: $3–$9 per sq.ft.

• Full waterproofing: $5–$10 per sq ft.

Not all basements need sealant, but it helps to avoid future repairs. Repairing water damage costs $3,000 or more. Extreme damage can lead to complete rebuilds.

Piles

Installing piles costs $25 to $70 per linear foot of pile with a minimum cost of $32,000. That price includes labor, equipment, and materials. 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 hire a structural engineer for pile foundations.

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.

Foundation Replacement Cost

A full foundation replacement costs $25,000 to $115,000. If you see signs of damage or settling, such as cracks, it is important to pursue repairs right away. Foundation repairs cost an average of $4,800.

Structural Report

Hiring an engineer costs $525 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

Raising and replacing your foundation costs $25,000 to $115,000. You’ll need to budget for the following three parts of the project:

• Raising your house costs $3,500–$10,500

• Excavating costs $1,500–$5,600

• Rebuilding runs $25,000–$120,000

DIY vs. Hiring for Foundation Work

This isn’t a project you should DIY unless you have experience and a working knowledge of soil types, hydrostatic pressures, and engineering. Improperly installed foundations can cause your entire home to fail. Professionals also have the right equipment to excavate your property, grade the soil, as well as pour and finish the concrete. Hire a local general contractor to oversee the project or find a foundation installation company near you.