Table of Contents for this Page
- Slab Foundation Cost
- Slab Foundation Cost Range
- Average Total Costs
- Overview of Concrete Slab Foundations
- Slab Foundation Cost Factors
- Installation and Supplies Cost Details
- Permits, Inspection, Related Costs and Installation Time
- Related Projects
- DIY or Hire a Pro for this Project?
- Comparison Costs from Leading Resources
- Common Questions and Answers about Concrete Slab Foundations
Cost Range for Concrete Slab Foundations
The cost range to have a slab foundation installed is fairly wide at $6,280 – $21,000. There are many factors that go into this range, which are outlined in detail below. The average slab foundation cost is $9,750 or about $7.80 per square foot. This price includes everything from excavating the foundation to finishing the concrete.
After excavation, the footings are poured and a base layer of gravel or stone is added and covered with a vapor barrier (optional). At this point, other contractors like your plumber or electrician will need to oversee or install any utilities or features like heated floor tubing required for the mechanical in your home that are set in to the slab. They will likely need to be inspected before the slab is completed and before concrete is poured. Finally, up to 6 inches of concrete are poured to form the slab foundation, reinforced with steel rebar and the surface of the concrete finished.
Note: In addition to footings, many concrete contractors prefer to make the edges of a slab foundation thicker – up to 10 inches – to improve the stability and strength of the foundation.
Just like concrete driveways, costs are slightly lower when only 4 inches of concrete are poured, and they can be higher when deeper excavation and additional base layers are required in unstable soil.
Overview of Slab Foundation Installation
A slab foundation is one of several common foundation types along with a crawlspace and block or poured full foundations. Slabs are more common in warmer parts of the country. In climates with freezing winters, frost in the ground may cause a slab to heave and crack. Additionally, most slab foundations are used where high groundwater levels eliminate the possibility of choosing a crawlspace or basement. An engineer, possibly with the same company that handles your perc test or land survey, can help you decide if a slab foundation is the best choice based on ground water, soil compaction and several other factors.
Concrete aka cement slabs are also a low-cost choice for use with additions that expand the home’s footprint. Pole buildings and barns also use slab foundations, though the focus of this page of Costimates is on foundations for new homes and residential dwellings.
Most homeowners choose a local contractor for their foundation, though DIY is possible. Keep in mind that this is one of those homebuilding projects that must be done absolutely correctly to ensure, first, that it will pass inspection and, in the long run, that the foundation will provide the durable stability any house needs. There’s more on DIY slab foundations below.
Concrete Slab Foundation Cost Factors
There is more than a $4.50/square foot difference between the low and high cost of a slab foundation. With that in mind, it will be useful to consider cost factors that will assist you in narrowing your concrete slab foundation estimate.
- Foundation Size – Larger foundations cost more, of course, but price per square foot goes down by as much as $1 as the size of the foundation increases. This is because transportation and setup/tear down costs are spread over more square feet of work.
- Access to the Site – Where access is hampered by slope, trees, brush, very wet conditions or other impediments, cost is higher. If a concrete pump must be used in order to pour concrete from trucks parked on the street, cost will rise toward the high end of the spectrum.
- Amount of Excavation and Base Materials – When the soil is heavy clay, more of it must be removed to provide a stable base for the concrete. As a result, more gravel or stone must be installed prior to pouring the concrete and footings must be deeper.
- Concrete Thickness and Strength – The typical slab foundation is 4” to 6” thick, and 3000 PSI concrete is standard. When a thicker foundation or higher PSI material is used, cost will rise. For example, a stronger and/or thicker concrete might be employed with a 2-story home vs a single-story dwelling.
- Number of Corners – Framing the foundation takes longer when there are more than 4 corners, so cost goes up.
- Potential Freezing Weather – Adding antifreeze to the concrete that allows it to cure without freezing slightly increases cost.
- Engineer or Architect Fees – In rare situations, local codes or the inspector require a foundation design produced by an engineer or architect, and their fees add considerable cost to the project.
- Utilities and Features – If you have several utility runs like plumbing and/or electrical, it requires a bit of extra work and care by the concrete company handling the slab. In addition, if you opt for a heated floor, the plumber will need to be involved with the foundation company, to assure all heated flooring lines are properly placed, slowing the work a bit.
- Permit Fee – Any foundation requires a permit, and cost varies by county/municipality. A range is provided below.
Slab Installation Services and Costs
It is difficult to itemize the costs for a slab foundation. But the raw materials can be priced easily. Prices include delivery.
- $35 – $55 per Cubic Yard | Pea Stone or Gravel
- $110 – $160 per Cubic Yard | Concrete
- $0.12 – $0.20 per Square Foot | Vapor Barrier
- $0.55 – $0.70 per Square Foot | Steel Rebar or Mesh Reinforcement
A cubic yard of material covers 81 square feet to a depth of 4”. Most slab foundations require up to 2-4” of pea stone or gravel and 4-6” of concrete.
Foundation Size and Cost
It might be more useful to give costs for common size foundations.
Easy: 4-6 corners, easy access, good conditions, standard 4” slab. Example: A flat, cleared suburban lot in dry conditions with building site near the road.
Average: 4-8 corners, some access difficulty, fair site conditions, enhanced strength 4” or 6” concrete slab. Example: A flat or gently sloped building site set off the road in damp conditions or with numerous trees or brush to work around. Possible freeze conditions.
Difficult: 6+ corners, difficult access/concrete pump, 6” enhanced strength slab. Example: A moderately to significantly sloped large lot with wet conditions and other obstacles. Concrete pump required. Freeze potential could be a factor.
800 Square Feet – $7.85 to $11.50/square foot
- Easy: $6,280 – $7,450
- Average: $7,300 – $8,550
- Difficult: $8,275 – $9,200
1,200 Square Feet Foundation – $7.25 to $11.00/square foot
- Easy: $8,700 – $10,800
- Average: $10,650 – $12,00
- Difficult: $11,750 – $13,200
1,600 Square Feet Foundation – $7.00 to $10.80/square foot
- Easy: $11,200 – $13,900
- Average: $13,600 – $15,500
- Difficult: $15,250 – $17,300
2,200 Square Feet Foundation – $6.85-$10.50/square foot
- Easy: $13,750 – $19,200
- Average: $14,800 – $20,1500
- Difficult: $15,700 – $21,000
Permits, Inspection, and Labor Costs
Permits and Inspection
- $125 – $500 | A permit is required. The size of the foundation and general costs in your area affect price.
In concrete work, labor costs are often higher than material costs. In fact, Homewyse claims that labor costs are about 66% of the total cost of a concrete slab foundation, and that’s pretty accurate.
Here are major components of the labor cost part of the equation along with factors affecting the cost.
- Excavation | $100 – $200 per hour. If the contractor owns the excavator and the operator is an employee, cost is lower than if an excavation subcontractor is hired. Slab foundations require 2-4 hours to dig.
- Base Materials Delivery | $35 – $55 per cubic yard. Cost is affected by the specific material – gravel costs less than pea stone – and the distance from the supplier to the site.
- Concrete Delivery | $110 – $160 per cubic yard. The specific concrete mix and the distance from the supplier to the site affect cost.
- Wages | $20 – $45+ per hour. Wages in the concrete industry range from around $20 an hour for laborers to $45 or more per hour for the crew foreman or a skilled concrete finisher.
Time Required to Install a Concrete Slab Foundation
Schedules for digging and pouring any kind of foundation can be interrupted by weather and other delays. In climates with freezing winters, road restrictions or “frost laws” go into effect in late winter or early spring that prohibit heavy vehicles like cement mixer trucks from traveling on most local roads until the ground is fully thawed.
In the busy season for concrete, you might have to wait up to 4 weeks to get on a contractor’s schedule, so plan early and get the job scheduled to avoid a lengthy wait for your home’s foundation. After all, nothing else gets done until it is installed.
Once work begins, and if it isn’t interrupted, here’s a typical schedule.
- Up to 1 Day | Excavation of the Foundation Site
- 2-6 Hours | Placement of the Forms
- 1-3 Hours | Installation of the Base Materials – Sand, gravel and/or pea stone.
- 2-4 Days | Installation of Plumbing – A slab is a unique foundation type in that plumbing and sewer pipes often run beneath the foundation rather than inside the foundation as with a crawlspace or full basement. Radiant floor heating systems might take longer.
- Up to 1 Day | Pour and Finish the Concrete Slab
- 1-2 Hours | Return in 3-7 Days to Remove Forms to allow the building project to proceed
A foundation is one of the first steps in home construction. When the contractor does a superior job, keep the company in mind for other flatwork projects around your home like the driveways, patio and sidewalks, etc.
Are You a Pro Foundation Installation Company?
If so, head over to our Costimates Pro’s page, and help us make this page better and more accurate for both our visitors and your future customers.
DIY or Hire a Pro
Anyone who tells you that concrete work is hard but it isn’t rocket science probably hasn’t done a lot of it. They’re right about the hard work, but they are wrong if they think it doesn’t take knowledge and expertise to get the job right.
That’s why most people hire an experienced slab foundation installer to ensure:
- The ground is properly compacted, and the right base layers are used, so that the soil doesn’t settle later and lead to cracks and possible sunken sections of concrete that cost $10,000+ to repair or replace.
- The right concrete mix for your climate, the time of year and the weight of your home is chosen to produce the best results.
- The work is scheduled so that steps to concrete slab construction proceed efficiently and in the right order.
In addition, once you consider that contractors get wholesale prices on materials not available to homeowners and that you’ll incur heavy equipment rental costs by DIY, hiring a contractor looks like a pretty good value.
Compare Costs from Leading Resources
- HomeAdvisor: $4,068 - $13,446, Complete Cost
- HomeGuide: $4 - $8, Per Square Foot
- Remodeling Expense: $6.88 - $14.61, Per Square Foot
- Everything About Concrete: $6.00 Base Cost, Per Square Foot
- Fixr: $7,000 - $18,000, Complete Cost
- HomeWyse: $9.40 - $11.20, Per Square Foot
Common Questions and Answers
What is slab foundation cost?
$6.85-$11.50 per square foot.
How long do I wait to build on a slab foundation?
Usually about 1 week. The concrete is fully cured in about 28 days.
Are slab foundations good?
Yes. If you live in an area where a crawl space or basement isn't possible because of ground conditions, a slab foundation is ideal. It is also a more affordable option anywhere.
How long do slab foundations last?
75 to 100 years or longer. When properly installed, a concrete foundation lasts indefinitely.
What are the advantages of a slab house?
The foundation cost is lower than for a crawlspace or basement. You won't be concerned about leaks and flooding with a slab. They are also a cost-effective choice for a home addition or extension.
What are disadvantages of a slab house?
You won't have any space under the home for storage or living space.