How to Insulate a Room Above a Garage

The bonus room above your garage often gets the short end of the stick when it comes to comfort. 

Too hot in the summer, too cold in the winter, and sometimes filled with odors or noise from the garage below. This space can be one of the most frustrating rooms in your house.

But since that space often serves as a bedroom, office, playroom, or even a nursery, getting it right is crucial. Let’s walk through how to insulate a room above a garage step by step, so you can turn it into a space that’s cozy, energy-efficient, and healthy.

Why Insulating a Room Over the Garage is Tricky

A room over the garage isn’t like any other room in your home.

You’re battling air movement from the big garage door, temperature swings, and even the potential for exhaust fumes to creep in. That’s why bonus room insulation needs to address the ceiling, walls, and floor to get the comfort and efficiency you’re looking for.

Insulating the Ceiling Above a Garage Room

The ceiling of your bonus room plays a big role in how comfortable the space feels.

How you insulate the ceiling depends on the setup.

• Vaulted or cathedral ceiling: Spray foam insulation is typically the best choice. Contractors cut strips into the ceiling, spray the foam into the rafters, then replace the drywall.
• Attic above the bonus room: If you plan to use the attic for storage, spray foam would be applied to the roof deck, making it part of the conditioned space. If you don’t plan to use the attic, then the spray foam is applied to the attic flat, sealing it off from the rest of the house.

Either way, spray foam provides an air seal that stops drafts and keeps the temperature stable.

Insulating the Walls of a Bonus Room Above a Garage

If your room is already finished with drywall, injection foam insulation like RetroFoam is a smart choice.

• Vinyl or wood siding: Contractors remove a strip of siding, drill small holes, inject the foam, then patch everything back up.
• Brick exteriors: Small holes are drilled at the top, middle, and bottom of each cavity, filled with foam, and sealed with mortar.

For remodels or unfinished spaces with open wall cavities, spray foam can be applied directly to the studs before drywall goes up.

Insulating the Floor of a Room Over a Garage

Here’s where most of the comfort problems start.

The floor of your bonus room is the garage ceiling, which means it’s directly exposed to:

• Drafts from the garage door (or multiple garage doors).
• Extreme garage temperatures.
• Noise from tools, cars, or woodworking.
• Exhaust fumes and odors.

Spray foam applied to the underside of the floor creates an airtight seal. This not only keeps your room more comfortable, but it also:

• Dampens noise from the garage.
• Blocks fumes and odors from entering the living space.
• Improves overall energy efficiency by preventing conditioned air from escaping.

Why Foam Insulation is the Best Choice for a Bonus Room

When it comes to insulating a bonus room above a garage, the real solution isn’t just about R-Value; it’s about air sealing.

Fiberglass and cellulose still allow air movement, which is why they can’t solve the comfort, odor, and noise issues you’re experiencing.

Both spray foam and injection foam insulation create a true air barrier, making your bonus room:

• More comfortable year-round.
• Quieter.
• Healthier for your family.
• More energy-efficient.

Ready to Fix That Room Above Your Garage?

If you’re tired of dealing with a drafty, noisy, or uncomfortable bonus room, foam insulation is the answer.

Check out our Dealer Finder to connect with RetroFoam dealers across the country who can help transform your bonus room into the cozy, efficient space it should be.

On the flipside, if you’d like to read up a little more about all of the benefits of foam insulation, check out our Learning Center.

Key Points:

• Bonus room ceiling insulation: Spray foam works for vaulted ceilings or attic spaces (roof deck or attic floor).
• Wall insulation: Use injection foam for finished walls, or spray foam for open wall cavities.
• Room over the garage floor insulation: Spray foam on the garage ceiling seals out drafts, noise, and fumes.
• Foam insulation is the only solution that provides an air seal to tackle comfort, odor, and efficiency issues.

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