How much does a concrete foundation cost?

Concrete is made from sand, gravel, water and cement, which is lime-based and acts as a binding agent. Concrete can be mixed up on site, delivered by a truck or poured into place using a crane system equipped with a pump. Typically, when a contractor builds a new structure, they will include the cost of pouring a concrete foundation in their overall project bid.

Whether you want to figure out how much you should pay for this line item on your overall construction contract or need to hire a separate contractor to take care of this step (after all, many contractors specialize in concrete and masonry), this guide will help you figure out the total cost of laying a concrete foundation.

You can estimate the cost of your concrete foundation based on a cost-per-square-foot of concrete the contractor will lay. This usually ranges from $4 to $7 per square foot.

Although many different factors will impact the overall cost of laying a concrete foundation for a new home or building, the square footage of the space is one of the biggest. Below is a breakdown of the national average cost for a concrete foundation based on square footage:

• 3,000 - 15,000 square feet: $15,046
• 2,500 - 3,000 square feet: $12,240
• 2,000 - 2,500 square feet: $10,022
• 1,500 - 2,000 square feet: $6,487
• 1,000 -1,500 square feet: $5,747
• 500 - 1,000 square feet: $5,318
• Under 500 square feet: $2,417

The total cost of laying a concrete foundation will include more than just labor costs and material costs. When you hire a contractor to lay a concrete foundation, any one of the following services and add-ons might be included in your total. All of them vary individually, and can impact the overall cost of your project:

Soil testing or drainage

A concrete pour typically starts with a soil test to determine the best mix of concrete for the job and how much excavation you will need. How well a site drains and how rainwater moves on the site are also key considerations.

Whether you need assistance obtaining building permits

Most licensed contractors help clients navigate the process of applying for necessary building permits. The plans and drawings needed to get the permit must be in compliance with the local building codes. Some contractors will acquire permits for their clients, with an added fee to cover their time in addition to the permit fees.

Whether or not you'll need excavation

Building on a sharp grade is more complex than a flat surface. The builder will have to secure the foundation with deeper footings or other methods, all of which cost more.

Similarly, if you need to level the area on which the foundation is to be laid, the total cost will increase by about $2,000. It will also extend the project timeline by a couple of days.

The depth of your foundation

The depth of the foundation is another key pricing factor. Foundations are described as:

• Deep: those that need to be more than three feet into the earth
• Shallow: as in standard slab-on-grade foundations, which consist of a single layer of concrete poured on a flat surface over a layer of gravel for drainage.

In general, the deeper the foundation, the more it will cost to lay, since you will need more concrete and it will take longer. For example, you will pay more to pour the foundation for a crawlspace than you would for a full-height basement.

The number of footings needed

Footings are relatively shallow columns of concrete dug into the ground at the edges of a foundation to support architectural features such as stairs. Each individual footing costs around $150 and, if you need them, can add to the overall price.

Adding a full basement or walls

Pouring a foundation for a structure that will have a basement is more complicated and expensive than a standard foundation, since concrete walls will be added to define separate rooms.

A full basement can add $13,000 to $30,000 or more to the total cost of building a new structure, depending on the width and height of the walls and whether the space includes utility hookups, windows and other features.

Whether you're building a basement, adding vertical elements (like a foundation wall) to a project increases its complexity. Expect this to add an additional cost as well.

Whether you want to finish the foundation

One of the last steps of a typical concrete job is finishing, or honing the pour. This is done by vibrating the wet mix to remove any bubbles in the pour. Then, using a buffing machine while the concrete is still damp, the contractor will smooth out any irregularities to create a finished surface.

There are two common types of foundations you will encounter: Slab and block. Both have different structural engineering benefits, but both can be reinforced with a steel rebar.

While each can influence the overall price of your project — especially since block foundations sometimes incur additional labor costs — which one you choose should be determined by the specific needs of your project, not budget.

Slab concrete foundations

A slab foundation is one made from a concrete slab, often laid over soil-based areas. Think of the concrete slab as the floor under the floor of your house. A slab-on-grade foundation is one done over a flat surface, and are the most straightforward and affordable type of concrete foundation. They tend to cost between $5 to $8 per square foot. 

Costs are higher if you need to dig and pour footings for a crawl space under the structure or if the structure will have a basement that can be used as living space—both require more excavation, as well as additional materials and other costs.

Block foundations

Concrete block or cinder block can also be used to build foundations. Although the two terms are used interchangeably, they are different types of material. Cinder block typically contains fly ash as an aggregate. Cinder block also tends to be lighter than concrete block and lacks its tensile strength.

Both types of block are popular because they're affordable and relatively easy to install. Local building codes may forbid foundations from being built with cinder block and instead require you to use concrete block.

The cost to install a concrete block wall starts with the price of the individual block, which generally runs between $1 to $3 each. Blocks that mimic the look of natural stone will cost more. Once you know the price of the block, the amount of square feet needed for the job will determine the final price. You can expect to pay $4 to $7 per square foot for an installed concrete block foundation.

The foundation for your house or building is not a part of the construction process you want to skimp on -- especially since it plays a pivotal role in the structure of your building.

However, there are a couple of expenses that are cheaper to do at the foundation phase. While they increase the cost of this project, they are generally easier and cheaper to do before you start the rest of your construction. Installing these items now can save you a lot of headache and trouble later on:

• Radiant heating for the floors - around $2–$3 per square foot
• A foundation drain - around $3,000
• Proper sealing to keep out moisture - about $0.05 per square foot