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.
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.
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.