Building a bonus room that feels just right

Plan for proper insulation and ductwork to make space above garage comfortable

A lot of homes feature a room above the garage. Often referred to as a bonus room, these rooms are designed to create some extra livable space in a home, without having to expand into the yard. They make great additions to a home with a smaller lot, and can be used as an office, play space for the kids, or a getaway spot for mom or dad.

But usually when I hear from homeowners who have problems with their bonus room, it’s when they’ve turned it into a bedroom. It looks great, and provides some nice privacy from the rest of the home, but the person who sleeps there says it gets way too hot in the summer, and far too cold in the winter.

So how do you deal with an uncomfortably cold bonus room? Here’s how you make it right.

THE INS AND OUTS OF INSULATION

It’s when the temperature of your bonus room starts to match the outdoor air that you know there’s a problem. The main culprit will likely be your insulation — or lack of it.

Typically, a bonus room will be positioned in the house in a way that more walls are directly exposed to the outdoor elements, so if you don’t have sufficient insulation behind the walls, you’re going to feel it.

Usually the biggest offender will be inadequate insulation between the floor of the room and the ceiling of the garage.

You may be opening your garage several times a day, and when that cold air rushes in, without enough insulation, you’re going to feel it in the room above.

To start, I would pull down the drywall in the ceiling of the garage, take out the old insulation and replace it with spray foam insulation. I like spray foam because it will also provide the thermal break to prevent the hot air from meeting cold air.

This keeps out moisture — which, if it creeps in to your insulation, can cause damage and reduce its effectiveness.

Knee walls are a common feature in the room above the garage. These are short walls that you’ll find underneath peaked ceilings. Even though they’re small, if they’re not properly insulated you’ll feel the chill in a big way. If you’re using spray foam to insulate, you should only need to insulate the peaked section of the ceiling, and not need to insulate the wall itself.

When you’re adding more insulation, go ahead and take photos of the process. That way, if you ever go to sell the home, you can prove that you’ve made it right for the next owners.

WHAT THE DUCT IS THE PROBLEM?

When running ductwork in the home, often the bonus rooms ends up being farthest away from the HVAC system, meaning that your ducts have a long way to travel to supply heat.

The system can only work as well as it was built and if your HVAC system simply doesn’t have the power to supply the heat needed, you’ll need to address that.

First, while you’re adding insulation to the knee wall, you’ll want to make sure your ductwork is on the warm side of the insulation.

An HVAC technician can help you source the root of the problem, whether it’s an undersized furnace, disconnected ductwork, seams that aren’t properly sealed, or a system that needs to be properly balanced (to improve air flow).

Homeowners looking for a quick fix may try to install a duct booster fan instead of doing the legwork, and to me, that’s just putting a Band-Aid over a bigger problem.

For rooms that are always either too hot or too cold, the idea is that the booster fan will help push the needed air to the room.

And booster fans can be loud, too — you may learn to deal with the noise, but I don’t think I’d be able to stand it.

When you think of bonus room, it should be just that: a bonus that you can enjoy just like any other room in the house.

A room that’s too hot or too cold half the year sounds more like a nightmare to me, but I know you can make it right. Watch Mike Holmes in his series, Holmes Makes It Right, on HGTV. For more information, visit makeitright.ca.