Wrtten by MIke Holmes:

I love my garage. I get some of my best ideas in there. It’s where I go to get away from all the chaos, to unplug and decompress. Actually, it’s the reason I bought the property I live on in the first place. I’m just lucky there was a house there.

Garages are practical. Besides keeping your cars there, they’re great to store tools, building materials and extra stuff like tires and bikes. You can add a small workshop in the back too, depending on how much space you have.

When we talk about garages there’s attached and detached.

Attached Garages

If your garage is attached to your house, the most important thing is to make sure it’s sealed. You must keep fumes, exhaust and carbon monoxide out of the house.

I can’t tell you how many times I see, in new construction, that they’ve used a wall cavity in the garage as a return air duct to feed the furnace. You never want to use the inside of your garage as an air return.

First, you get minute particles being pulled inside your home. Your family breathes this in every day. Not to mention that having an open cavity — which means there’s no metal ducting — can draw the off-gassing from running vehicles in the garage into an open space behind the drywall.

I don’t know why any builder would do this. But they do, and it’s wrong. If there are vents going from your garage to the inside of your home, you need to get them redirected. You don’t want to risk carbon monoxide coming inside the house. And call in a professional HVAC contractor to do the job.

Aside from stopping fumes, you need to make sure that a fire starting in the garage can’t spread to the inside of the home. Install a 20-minute fire-rated door between the garage and the inside of the house. The door shouldn’t open into a bedroom. And it shouldn’t have a pet door, either.

The door should be about an inch thick and self-closing. All garages need a door closer on the door. Think about it: Your car’s running. Fumes are going to go inside the house. Not good.

I’ve also seen a lot of homes with rooms on top of the garage. If there’s a room above the garage it’s going to be cold, because there’s a lack of insulation or at least improper insulation. This is why we spray-foam garages. It gives us a thermal break. Not to mention that closed-cell spray foam gives us a barrier between the carbon monoxide and the inside of the home.

Should all garages be insulated?  The depends. What does your local building code dictate? Is there plumbing in the garage? If so, the plumbing has to be insulated.

Is the garage heated? If it isn’t, you don’t want to insulate; doing so can cause mildew.

But if the garage is heated you should definitely insulate. Use fibreglass, cellulose, foam board or closed-cell spray foam — if it were my garage I’d go with spray foam. Then cover it with drywall for fire resistance.

Attached garages are one of the biggest sources of heat loss in a home, because of air leakage. Garage doors are big; a lot of air can get by them. To stop this, get tube-shaped stripping for the bottom of the door. The tube stripping forms a seal when it compresses against the floor of the garage.

Detached Garages

A detached garage eliminates the risk of dangerous fumes coming into the house, so you don’t have to worry about making it super sealed. All you have to worry about is that it’s the right structure and the right size.

Building a detached garage means you can make it as big as you want. Or as big as your lot allows. For me, the bigger the better. But even if you don’t want a big garage, make it slightly larger than what you need — if you can.

After going through the trouble of building, you want to be sure you’ve got enough space. You never know when you might need more room to store new tools, equipment, or even a new toy. Depending on the materials you use, the extra space could be worth the extra cost.

In the bigger picture, most people don’t think about their garages when it comes to renovations. But it’s important. If it’s attached to the house it will affect your home’s safety and energy performance. It’s worth bringing in a certified inspector to make sure it’s properly sealed and to code.

And if you’re going to build a detached garage make sure you hire pro. Check references and take a look at other garages they’ve built. See how they’ve held up through the seasons. Speak to those past clients. Are they happy with the contactor’s work? Doing your homework can save you money and a world of grief.