House Foundations | Types, Costs and FAQs | Square One (2024)

What is a foundation?

A foundation is simply the lowest load-bearing part of your home. It serves three main purposes:

1. It bears the weight of the entire house, transferring the force through to the ground beneath. For this reason, most (though not all) foundations are made of concrete and dug into the earth for added stability.
2. It essentially holds your house in place, acting as an anchor between the frame (the walls, ceilings, etc.) and the ground below. In the event of natural disasters (such as earthquakes, hurricanes and tsunamis) or more routine adverse weather conditions (such as floods, wind, and frost-heave) your foundation stops your home from being washed or blown away.
3. Finally, a well-laid foundation can help waterproof your property and prevent groundwater from rising into the lower reaches of your home.

The majority of foundations in Canada are made primarily of concrete. Depending on the design, it can be poured concrete walls, a concrete pad, concrete pillars, or insulated concrete forms. Less common materials include stones, wood, or metal pilings. Rather than focusing on what a foundation is made of, foundation types are usually categorized based on the form they take — which can be very different from one another.

Types of foundation

There are three types of foundation commonly used in homes across North America: basem*nts, crawl spaces, and slabs. The best type of foundation for a home depends on the climate, soil and groundwater levels in the area.

Let’s look at each of these common types of house foundations:

Basem*nt foundation

Basem*nts are so common, and so integrated into the building, that many people don’t even think of them as foundations. Modern basem*nts are usually constructed of concrete that’s poured to form a hollow, below-grade structure. The concrete is usually reinforced by rebar, and sometimes with large foam forms.

“Below grade” simply means below the ground. So, before the concrete is poured, contractors will excavate and treat a hole in the earth. Basem*nts are usually between 6 and 8 feet deep, depending on soil conditions. When the base of the foundation is laid, it forms both the bottom-most load bearing element of your home, and the floor of the basem*nt.

Basem*nts can be either fully and partially below grade. Some owners prefer the latter option as it often allows more natural light into the property, which has advantages when the space is used for residential purposes.

This brings us onto the second element of basem*nt construction. Basem*nts must be large enough for an adult to stand in. If you can’t stand in the lowest floor of your home, your foundation is either a crawl space or a basem*nt built before the current basem*nt height regulations went into effect.

Common terms you may hear regarding homes with basem*nts are finished, unfinished, full<, and partial. Unfinished basem*nts are not designed to be lived in. Often the walls and floor are the bare concrete of the foundation. The basem*nt may contain electrical wiring systems, plumbing pipes and your hot water heater. A finished basem*nt is one that’s fit for habitation, usually with drywall, flooring, a finished ceiling, and other comfortable features similar to what you’d find on the main level of the home.

Many think of a finished basem*nt as synonymous with a full basem*nt, but this isn’t quite true. A full basem*nt is simply one that’s big enough to stand in — so your basem*nt can be full, but still unfinished. A partial basem*nt is one where only a portion of the space is big enough to stand in. The rest might be similar to a crawl space.

As mentioned above, modern basem*nts are usually constructed of poured concrete. Older homes and those located in dry regions may use concrete blocks or bricks. While a block foundation is reasonably solid, it does present an increased risk of water intrusion and can make it more difficult to determine the cause of a loss.

Crawl Spaces

A crawl space foundation raises your home 1 to 3 feet off the ground. It’s got enough space to crawl, but not to stand — hence the name. Crawl spaces are common in moist climates, as the home is elevated from the damp ground.

Crawl spaces are fully enclosed and can’t be used as living space. Some serve as a location for plumbing pipes and other utilities. Some homeowners use their crawl space for storage, but this isn’t the best idea. Moisture from the damp ground can enter the crawl space and damage the stored property, especially organic items (such as paper records) or items stored in cardboard boxes.

For the same reason, crawl spaces are prone to mould and bacteria growth which can cause damage to wood floors and surfaces, drywall, and some types of insulation. If you’re considering a crawl space foundation, be sure to take the proper steps when sealing and venting the area. Check out our guide on how to waterproof your basem*nt for more on that topic.

Slab foundation

A slab foundation, as the name suggests, is a slab of concrete that sits on the final grade of your property. The concrete slab is usually a few inches thick, poured thicker at the edges to form a footing. Reinforcing steel rods then strengthen the slab from within. The building’s frame is connected to the slab.

Concrete slab foundations are the simplest and cheapest type to manufacture, requiring very little on-site preparation. From a structural perspective, concrete slab foundations provide a durable, level surface for floors; homes built on slabs rarely experience problems with creaking fixtures as the home settles over time.

The downside of a slab foundation relates to its strength in extreme conditions. As it’s not dug into the earth, a slab foundation doesn’t provide as stable a base for your home as a basem*nt or crawl space.

Foundation maintenance and repair

Foundations are big, heavy, and bearing the weight of your whole home. If there’s something you need to fix, you’ll need to hire a contractor with appropriate equipment. For that reason, foundation maintenance mostly involves monitoring the foundation’s condition.

At least twice each year, do a quick visual inspection of your home’s foundation:

1. Examine the visible outdoor portion of the foundation, looking for cracks or other signs of deterioration. Small cracks are not necessarily cause for alarm, and may be caused by the building settling — unavoidable in many cases. It’s possible to repair minor cracks with special sealant, but you should consult with an expert just in case they’re signalling a larger issue.
2. Check anywhere a window, vent, pipe, or other object is set into the concrete foundation. If any caulking around these items has deteriorated, remove the old caulking and re-do it to ensure a tight seal.
3. Look for eroding soil around the foundation. Soil erosion is caused by drainage issues and can weaken the foundation itself. If you see such an issue, you’ll need to improve the drainage around your foundation.
4. Avoid planting trees or shrubs too close to the foundation walls as the roots can damage the concrete. Remove any large vegetation growing up against the building, or see about getting a root barrier installed.

If you see any issues with your foundation, don’t hesitate to get a professional involved.

Foundation repair costs

If you do find damage to your foundation, you’ll have to hire a contractor to fix it. The cost of those repairs depends on the nature of the damage.

Small cracks are often repairable with a simple application of sealant, though some require a little more work. Expect to pay $50—1,000 for repairing small, non-structural cracks.

Unfortunately, that’s the good news. Any more serious repair work can get very, very expensive. If your foundation is crumbling, bowing, sinking, or otherwise losing structural integrity, the costs start at around $2,500 and more likely reach $10,000 or more. At this level, you may need to pay for an engineer on top of the actual work. If the damage is severe enough, you may have to pay to lift the house and replace the foundation entirely — an undertaking that will cost at least $20,000 and likely much more.

House foundation repair costs are high, but there’s not much you can do. The alternative is watching your home crumble and sink into the Earth.