Crawl space

What To Do With a Crawl Space

By Mike Holmes

Mike’s Advice / Home Renovation

Wednesday, April 18th, 2018 @ 12:00pm
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If you’re in an older home with a crawl space, it’s likely unheated and not insulated. Many homeowners don’t know how to properly take care of the space. In fact, unless you’re using it as an extra storage area, you may not even know the state of your crawl space if you didn’t have a home inspection performed when you purchased – or checked it out yourself.

Before you get down and dirty with your crawl space, here are a few things you will want to know.

How Does it Stack Up?

Do you know what the stack effect is? Most people think of it as light, warm air naturally rising, but really, the cold, denser air is pushing that warm, light air up and away. If you haven’t properly insulated throughout the home, then you could also be losing heat through your attic.

If you live in an older home (you’ll generally find these crawl spaces unheated, unless a previous homeowner has made changes), and your crawl space has a simple dirt or gravel floor, it could be making it more difficult for you to heat your house.

When that cool air gets in, if your crawl space isn’t built to stop that air from meeting the warm air in your home, your systems will have to work overtime to keep the place warm. Not to mention, without a vapour barrier, you could be creating unnecessary moisture, which could lead to issues like mould and rot on your floor joists.

How to Insulate a Crawl Space

One way to deal with a cold crawl space is to make it part of the warm side of your house. You’ll need to close off the venting, insulate your foundation walls, and supply some heat to the space. A heating duct and cold-air return will balance out the air exchange to and from the crawl space. Before you commit to turning the space into a warm zone, you need to make sure your furnace is up to the task of heating that extra area. Your HVAC specialist will be able to tell you. If you’re concerned about the extra cost it will take to heat that extra space, you’re making up for it in pure efficiency.

To insulate the crawl space, I would use a closed cell, two-pound spray foam because it will act as both your vapour barrier and insulation. You could also use batt insulation, but don’t forget that you will also need to install a vapour barrier on the warm side of the insulation to keep the moisture out.

Making It a Cold Space

Another option is to make your crawl space a true cold zone, so it doesn’t suck heat from your home, or cause moisture problems. To make this happen, you’ll need the proper ventilation – two vents on either side of your cold zone should be enough. You’ll also need insulation under the floor of your home to keep it as the cold air underground and stop it meeting the warm air in the warm part of the house.

Any ductwork or piping that runs through your crawl space will need to be wrapped in insulation so they don’t freeze in the cold weather.

Is Expanding a Crawl Space Worth It?

Increasing the amount of livable space is a great way to add value to your home, I’m not going to deny that. But before you hire a contractor to build a basement, make sure you understand the scope of the project.

Expanding your crawl space into a full basement is a big job – and it absolutely has to be done right. To increase the space, you’ll need to have the area beneath the home excavated, as well as underpinned. When done wrong, it can cause major structural issues that make the home unsafe. If you really want to do it – make sure you hire a pro and expect a big bill. There’s no cheap way to do it right.

Ask yourself: is there another area you can expand to increase your livable space? My son opted to add a second storey above his home – and depending on your lot size you may be able to expand an addition into your yard.

The fact is, your small, cramped crawl space could be having a larger impact on your home’s energy efficiency than you might initially think. If you haven’t been paying attention to this hidden heat thief, now is a good time to check and make it right.

Make It Right®