House foundation types

Written by the Square One team

Updated July 8, 2024 | Published May 21, 2013

The foundation is the unsung hero of your home.

Often overlooked, it supports the entire frame of your property, prevents groundwater from entering your home, and can provide additional storage or living space. But did you know that the type of foundation your home uses can affect your home insurance premium? Here’s everything you need to know about the most common types of foundation.


Thumbnail of the Guide to House Foundations video

The important points

  • The foundation of a home is the lowest part, bearing the weight of the building and transferring the force through to the ground.
  • Foundations of Canadian homes are often concrete basements, though many forms of foundation exist.
  • Home insurance covers foundations just as it does the rest of the building, though foundations are susceptible to commonly excluded perils like mould or damage from shifting and settling.

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: basements, 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:

Basement foundation

Basement Foundation Type

Basements are so common, and so integrated into the building, that many people don’t even think of them as foundations. Modern basements 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. Basements 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 basement.

Basements 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 basement construction. Basements 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 basement built before the current basement height regulations went into effect.

Common terms you may hear regarding homes with basements are finished, unfinished, full<, and partial. Unfinished basements are not designed to be lived in. Often the walls and floor are the bare concrete of the foundation. The basement may contain electrical wiring systems, plumbing pipes and your hot water heater. A finished basement 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 basement as synonymous with a full basement, but this isn’t quite true. A full basement is simply one that’s big enough to stand in — so your basement can be full, but still unfinished. A partial basement 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 basements 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

Crawl Space Foundation Type

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 basement for more on that topic.

Slab foundation

Slab Foundation Type

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 basement 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.

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Home insurance considerations

When you buy homeowner’s insurance, you’ll likely have to answer some questions about your home’s foundation.

The type of foundation used in your home’s construction can impact your insurance premium, and in some cases determine whether coverage is available at all. For example, Square One will ask you what type of foundation supports your home, and what kind of waterproofing has been undertaken in your crawl space. We’ll also ask if the foundation shows any visible signs of erosion or cracking, which signal a decline structural rigidity.

Home insurance will cover the foundation just as it covers the rest of the home. If the foundation gets damaged by an insured peril, your home insurance will pay for repairs. It’s important to note, however, that many of the risks facing home foundations are the sort not covered by home insurance.

Policy exclusions

Every insurance policy features exclusions. Insurance is intended to cover loss arising from sudden and unexpected events, like earthquakes or wildfires. Predictable damage caused by lack of maintenance or simple wear and tear isn’t covered. For example, damage caused by the following perils is not covered under home insurance policies:

  • Wear and tear
  • Mould
  • Condensation
  • Contamination

Regarding foundations, policies also typically exclude damage caused by settling, sinking, buckling or cracking of the structure. This exclusion highlights the importance of selecting the right type of foundation for your location, and selecting a reputable contractor to undertake the work.

When considering the state of your foundation, the primary concern for an insurance provider is waterproofing. Rising groundwater, freeze/thaw cycles and tree roots can all compromise the integrity of a foundation. Once moisture gets in, it can be difficult to treat, often leading to further damage.

In some climates, it can be almost impossible to stop water from penetrating the earth that surrounds your foundation, so it’s vital that such foundations feature adequate drainage. It’s also a good idea to install a sump pump in your basement or crawl space. This pump sits in the lowest part of your home and activates once water is detected, moving it away from your foundation through a network of pipes.

Sump pumps are useful not only for homes in wetter climates, but also for any home that may experience storms or flooding. Square One may apply a discount to your premium if you have a properly installed sump pump with a back-up power system (such as a battery or generator). A sump pump can significantly reduce the chance of water damage at your property.

Commonly asked questions

What is the strongest type of foundation?

The best foundation depends on the location, particularly the type of soil. The strongest foundations are generally those dug into the earth to provide a stable base for the property above. While high-rise buildings like apartment blocks may excavate a pit of 30 metres or more for a foundation, 6-8 feet is usually sufficient for houses. Of the three types of foundations discussed in this article, basements provide the strongest platform for your home — hence their widespread adoption. If you’re thinking about building a home, discuss foundation types with your contractor and determine which will be the best type for your ground and climate conditions.

When buying a home insurance policy, the most significant cost item will be the building limit of coverage. Your foundation is part of that cost, but on average, the type of foundation is less likely to have an effect on your premium than other factors that you can control, like the type of roof, presence of a sump pump, and whether you have a claims-free history.

How do I make sure my foundation is waterproof?

Many waterproofing issues can be fixed through two simple solutions: adding or repairing gutters and downspouts so that water is able to drain away from your foundation, and grading your soil to slope away from your foundation so that water doesn’t settle. Consider installing a French Drain at your property and installing a sump pump. Other internal measures, like applying sealant to the foundation, can also be of value if professionally performed.

How much does a foundation cost?

The cost of a foundation depends on many factors, including the size of your home and the type of foundation you choose. As a general guide, expect to pay around $5 per square foot for a slab foundation, $8 per square foot for a crawl space, and $20+ per square foot for a basement.

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