Basements and crawl spaces

Written by the Square One team

Updated June 12, 2024 | Published October 16, 2018

Basements are a great way to add value to your home and make the most of your available living space. But basements (in fact, all below-grade structures) present specific challenges to homeowners – most notably waterproofing. So, here’s everything you need to know about basements and crawl spaces.

Basement of a home

What is a crawl space?

Most people are familiar with basements, but some may not have heard of a crawl space. To understand a crawl space, it’s necessary to have a basic understanding of home construction. As you’re probably aware, before the structural elements (walls and floors) of a home are put in place, a foundation must be laid. Building foundations have several purposes, but the principal functions are:

  • To evenly distribute the weight of the property
  • To provide a level surface from which to build
  • To increase stability by providing an anchor to the ground

There are three types of foundations. A slab foundation sits directly on top of the final grade of your land. There is no space between the ground and the lowest level of your home. A basement foundation is a hollow, below-ground structure that’s designed for living or storage. A crawl space foundation raises your home off the floor by around 1-3 feet; enough space to crawl, but not to stand- hence the name. Crawl spaces are often preferred 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. Most serve as a location for plumbing pipes and other utilities. Some homeowners use their crawl space for storage, but this is not recommended, as moisture from the damp ground can enter the crawl space and cause damage to 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.

How to insulate and vent your crawl space

As with most below-grade structures, the primary concern with a crawl space is moisture. However, with a crawl space, there are additional health and safety concerns that must be addressed as a result of a phenomenon knows as the ‘stack effect’.

Warm air in homes rises and leaves through the upper reaches of the roof. This creates an area of low pressure which draws air up from the lower parts of the home. Along with this air, mould spores, unpleasant odours and fecal matter from dust mites in the crawl space can be drawn into the primary living quarters. At best, this is an unpleasant thought. At worst, it can aggravate asthma and cause respiratory issues. So, what steps can you take to protect your home?

The first step is to cover your crawl space with a plastic vapour barrier that’s designed to deter the growth of mould and stop humidity from the earth entering the crawl space. Don’t be tempted to use a simple plastic tarp. While this will save a little money, a tarp won’t have the same anti-microbial properties as a proper vapour barrier.

If moisture is permitted to spread unchecked through your crawl space, a food chain develops. Mould feeds insects, which in turn feed larger pests (rodents, birds, etc.). A vapour barrier breaks this cycle and creates a physical barrier to prevent larger animals from entering the crawl space. For this reason, some experts recommend extending coverage to the walls of your crawl space. Beware though, that other experts (notably pest control agencies) disagree with this advice as it may make spraying for pests more complicated.

Vapour barriers are increasing in popularity, perhaps in part due to their simplicity. If installing yourself, keep an eye out for ‘polyethylene’ and opt for a sheet that’s at least 6mm thick. Materials for a 1,500 sq. ft. basement cost around $200-500.

As for ventilation, it’s important not to vent the crawl space directly to the outside air, especially if your home is located in a warm and humid area. This draws in moisture from outside which condenses, often onto your HVAC system or cold-water pipes located in the crawl space, leading to corrosion. The most popular option is to supply air from your HVAC system. If there’s already a duct system present, this shouldn’t be too expensive and the air from the HVAC system will help to keep your crawl space dry. We recommend pumping around 1 cubic foot per minute per 30-50 square feet of crawl space.

If your home doesn’t have an air conditioning system (or even if it does), you might consider installing a dehumidifier. This is the best way to prevent moisture from spreading in your crawl space. A dehumidifier reacts to (and controls) the conditions in the crawl space, whereas using your HVAC system relies on dry air in the rest of your home. This can be problematic in spring and fall, when the air coming into the crawl space naturally contains more moisture. A dehumidifier, on the other hand, can be programmed to activate once the air in the crawl space reaches a certain humidity. On the downside, they require maintenance and are expensive to purchase- the type you’ll need usually start from around $1,000.

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Types of basement

Here are some other types of basement that you may not have heard of.

  • Full: Not to be confused with ”finished”, a full basement refers to the space being big enough to stand in. This type of basement can be used for living space or storage and typically increases the value of a home.
  • Partial: A partial basement is one where only a portion of the basement is a space big enough to stand in. The rest might be similar to a crawl space.
  • None: Structures with no basement at all can be built on a slab foundation (like a garage), directly onto the ground (like a shed), or sit on stilts/pylons (like a cabin or mobile home).
  • Walk-out: A walk-out basement is exactly what it sounds- a basement with its own entrance that you can walk out of. These are most often seen in homes that are built into a hill- whether natural or artificially landscaped. Due to their aesthetically pleasing design, this type of basement can add significant value to a home.
  • Walk-up: A walk-up basement is different from a walk-out basement in that most walk-up basements contain dug-in stairs that go from the ground level down to the basement level as an entry/exit.

Finishing your basement

In the simplest terms, an unfinished basement is one that’s not designed to be lived in. Often the walls and flooring are the bare concrete of your foundation and the space may contain electrical systems, water pipes, wires and your hot water heater. A finished basement is a below-grade living space that becomes part of your home, just like any other floor.

Finishing a basement requires a significant investment, both in terms of time and money. That said, a fully finished basement is a great addition to your home. It adds value and gives you the option to rent a part of your home for additional income. So, how do you go about finishing your basement? Here are 3 key points to keep in mind.

1. Learn the rules

More specifically, learn the building codes and bylaws. These change city by city, so check with your local municipality to find out whether you need any permits for your proposed changes. This is particularly important if you’re planning plumbing and electrical work, which may have to be inspected. And remember, it’s your responsibility to ensure that the work carried out on your property is up to code.

2. Hire a pro

Finishing a basement can be a mammoth task. The work required is beyond the scope of the average handy-man, so don’t be afraid to ask for help.

Most specific home systems (plumbing, HVAC, etc.) require expert knowledge to be installed safely and correctly. We’d advise staying well away from these tasks, as well as those relating to the installation of your electrical panels, removal of hazardous materials (like asbestos), and digging out a basement if you don’t already have one. Consider money spent here as an investment- now’s not the time to save a few bucks.

3. Add value

Take the opportunity to make some improvements to your home that will increase its value. Insulate your water pipes, especially if you live in a cold climate. Pipes that contact exterior walls or are exposed to unheated areas of the home may burst, causing significant water damage. Insulating your hot water pipes can also save you money by reducing heat loss, thus allowing you to reduce the temperature on your thermostat.

Consider adding a 3½ inch layer of fibreglass to your basement ceiling for noise reduction and insulation. For even more noise reduction, you can isolate the ceiling drywall from the joists using resilient channels (you may need to visit a drywall supplier to find these).

Finally, consider installing a sump pump and a backwater valve. Sump pumps evacuate water from the lowest point of your home. A backwater valve is a one-way valve attached to your sewage system to prevent it from backing up. Forty-four per cent of Square One’s home insurance claims result from water damage. Aside from protecting your most valuable asset- your home- from water damage, installing these devices could reduce your home insurance premium or policy deductibles. For certain high-risk locations, installation may be requisite for insurance.

Heating your basement

Adding insulation will not only help control the temperature inside your basement, but will also add another layer of moisture control and provide sound proofing. Make sure to choose a type of insulation that includes a vapour barrier on both sides, or if you’re using spray foam insulation, install a vapour barrier first.

When designing your basement, consider the principal source of heat. Many consider a gas fireplace to be a great option for a basement. Besides the obvious aesthetic advantages- who doesn’t love a fireplace? – there are some benefits to placing a fireplace in the basement as opposed to elsewhere in the house. For example, the heat produced will be recycled as it rises through the rest of the house. And you may also be able to vent the chimney directly through the side wall instead of through the roof.

Alternatives to a gas fireplace include standalone systems (like a furnace) or a pellet stove. Other common types of heating include radiant floor, radiant panels (that attach to your walls) or a simple, standalone electric heater.

Waterproofing your basement

Just like a crawl space, it’s vital to protect your basement from moisture. Before you even start planning your build, thoroughly check your basement for water. Pools or drips coming through below-grade walls will need addressing. If you find any signs of water, deal with it before embarking on your basement renovations. A simple way to test for moisture is to tape 2-foot squares of plastic sheeting to the floor and walls. Leave them for a few weeks and then check for condensation. If it forms beneath the sheet, your foundation is not sealed. If it forms on top of the sheet, you may require a dehumidifier.

Most water issues can be solved by two simple measures; grading the soil to slope away from the foundation, and adding or repairing gutters and downspouts. If these measures don’t work or if you find serious water issues, consider installing a French drain (or perimeter drain). This is a perforated pipe that sits in a bed of gravel and attracts groundwater away from your foundation.

It’s also a good idea to make sure your gutter downspouts discharge water at least 1.5 metres from your home and that there aren’t any plants within 30 centimetres of your walls. Rotting roots can provide a pathway for water to reach your foundation.

Designing the perfect basement

Now comes the fun part- designing your dream basement!

Basements can easily become dingy, so try to draw in as much natural light as possible. Use multiple light sources, mirrors and light-coloured paints to exaggerate the effect. Remember to wall off areas that need extra privacy, like bedrooms. And leave the area around your hot water heater unfinished in case of leaks. Don’t forget that at some point your hot water heater (in fact, most of the systems in your basement) will need replacing. So, don’t build yourself into a hole you can’t get out of. A great cost saving tip is to keep your plumbing in place wherever possible, as re-routing pipes will quickly add to the cost of your renovation.

Finally, we recommend not removing any steel posts or studs that connect to concrete without first consulting a structural engineer. These fixtures may well be holding your house up… Literally.

Aside from that, let your imagination run wild! Designing a basement is a fantastic opportunity to be creative, so don’t forget to enjoy the process. Need some inspiration? Check out Sebring Design Build or The Spruce.

What will your home insurance provider want to know?

Your home insurance provider will require more details than simply the number of floors in your home. They’ll likely ask whether you have a full or partial basement, and ask the degree to which it’s finished. Insurers will also want to know if there are any signs of pooling water or leaks coming from the doors or window wells in your basement. For homeowners with a crawl space, you may find that the minimum requirement for insurance is a ground covering.

It’s also important to inform your home insurance provider if you use your basement as a source of income, as there are different risks associated with renting out a portion of your home. And, if you plan on finishing or renovating your basement, be sure to let your insurance provider know before you start work. Most home insurance policies contain a requirement that you notify your insurance provider before modifying the home. Advance notice will allow your home insurance provider to confirm that your coverage will stay in place during the work, and that building materials and completed finishes will be covered in case anything goes wrong along the way.

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