How To Insulate Your Garage - Garage Insulation Project
Insulating Your Garage
If you're like me, your garage is your oasis. A space where you can escape from the craziness and tinker around with your projects. Unfortunately, it's also the most uncomfortable space in your home.
Insulating and air sealing your garage will not only make your work more enjoyable, but you'll create a safer living environment for your family. You'll be able to get your work done without worrying about loud noises bothering the people on other side of the wall.
Air sealing and insulating your garage will also prevent deadly gases from entering your living spaces. All in all, not bad for a few hundred bucks and a weekend of your time.
Things to Consider when Insulating your Garage
Most garages are a refuge for all kinds of flammable and noxious stuff. Paint, gas, oil, cleaning products, pesticides and other chemicals are stored on garage shelves right next to the living spaces inside of your home. Battery chargers for your tools or car batteries can create sparks which easily ignite flammable fumes.
Warming up a car inside of a garage creates a lot of carbon monoxide. This deadly gas can seep through the walls and into your home.
Noise from your tools, motors or just plain tinkering around in your garage can wake up your spouse or children. Or just become an annoyance to anyone living in your home which can limit the amount of banging and working you need to do.
Insulating Garage Walls
In order to prevent gasoline and car fumes from seeping through the walls and into your home. You need to air seal the wall cavities between the garage and walls that are connected to your home.
Hopefully, your walls are not covered with drywall yet and you have access to the framing. If not, you'll have to decide if removing and replacing the drywall is worth the effort.
Air sealing the walls is cheap and easy. All you need it a couple cans of Great Stuff and a tube of silicone caulk. Start off by examining the wall. Look for any obvious holes, gaps or cracks like those usually left over from electricians and plumbers. Any holes where electrical wires or plumbing pierce through the wall need a good squirt of Great Stuff.
You may have light switches and/or electrical outlets on the wall that protrude through your home's living spaces. They are easily air sealed with a bead of silicone caulk around the perimeter of the electrical box where it protrudes through the drywall. Shoot a dab of caulk around any holes in the electrical box where the wires enter and exit. Then smooth it out with your finger. Be careful not to squirt too much into the box.
Then focus your attention on the bottom of the wall. Fumes can seep in underneath the wall framing where the wood rests on the concrete or block foundation. Run a bead of silicone caulk along the bottom of the wall between the wood and the concrete. Smooth it out by running your finger along the wall. This forces the caulk into the crack so it can completely seal out the fumes. If your wall has a double plate or two 2X4s resting on the foundation, shoot another bead of caulk in between the 2X4s and smooth it out.
Now it's time to air seal the wall cavities where the 2X4s touch the inside of your home's walls. Take a can of Great Stuff and quickly run the tip around the perimeter of the wall cavity while squeezing the trigger. Don't worry, it doesn't have to look good. No one is going to see it. This is especially important in the bottom part of the wall because most of the fumes are heavier than air and leak in down there. But it's cheap and easy once you get the hang of it. So I always grab a step ladder and air seal the entire wall.
Install the Insulation Backwards on Attached Garage Walls
When you're insulating a garage wall that is attached to your home, you need to install the insulation backwards. Fiberglass insulation designed for walls usually comes with a vapor retarder known as kraft facing. The paper side of fiberglass insulation is typically installed facing the living spaces in your home. When you are installing insulation from the outside of the wall, like you are in the garage, the paper should touch the interior part of the wall. So you need to install it backwards with the fuzzy part of the insulation facing you.
This only applies to the part of the wall attached to your home. When you reach the part of the wall that doesn't have a living space on the other side. You install fiberglass insulation with the paper side facing you. Staple the insulation's paper flanges on the edge of the stud, not on the inside. This allows the insulation to fill the entire cavity.
Side Note about Vapor Retarders
Your climate dictates the placement of the vapor retarder. In most parts of the U.S., a vapor retarder is recommended to control moisture within the wall. The exceptions to this rule are in the deep south where homes are air conditioned most of the year.
Buying the Right Insulation for Your Garage
Most garage walls are framed with 2X4s 16" on center. Which leaves a 14 1/2" gap that's 3 1/2" deep in between the studs. Perfect for the cheapest and most common 15" wide R13 fiberglass insulation. Garage walls vary in height which usually means buying rolls of insulation and cutting them to fit. But if your walls are exactly 92 5/8" high, buy the pre-cut batts and save a little time. If the walls are framed 24" on center or have 2X6 framing buy insulation that fills the space like 5 1/2" deep R19 or insulation that's 23" wide.
If fire prevention is your main goal, consider buying rock wool insulation for the walls adjacent to your living spaces. Rock wool is a dense, fire proof insulation made from volcanic rock. Installing rock wool insulation is the same as installing fiberglass insulation. You can buy Roxul rock wool insulation at The Home Depot.
Insulating the Garage Attic
If you're lucky enough to have a ceiling and attic access to your garage, adding a basic level of insulation up there is a good idea. Although it won't cut down on the noise, insulating the attic of your garage will make it possible to heat or cool the space with a small space heater or window air conditioner. Without insulation, it might be possible to make the garage more comfortable, but it will take a lot longer.
Blow it or Roll it?
Adding insulation to your attic can be done two ways. You can take the easy path and blow it in or you can haul fiberglass insulation up the ladder and roll it out. Each bundle may not seem heavy on it's own, but carrying dozens of bundles up a ladder and jamming them through a small opening in your ceiling is a pain. Blowing hundreds of pounds of insulation through a 3" hose is obviously easier than carrying it up through a narrow attic hatch and my advice is to blow it. Blowing the insulation is a lot faster and provides more even coverage.
If you decide to blow in the insulation, you'll have to choose between blow in fiberglass or cellulose insulation. Both are easy to install and provide even coverage in a short amount of time. The biggest difference between the two is that fiberglass is itchy and cellulose is dusty. But after an afternoon of crawling around in a dirty attic you're going to be dirty either way. Personally, I'd rather be dusty than itchy. Oh yeah, some studies have shown that the tiny fiberglass fibers could cause cancer, so dirty is sounding better and better.
You're Almost Finished!
By the end of the job, you'll be ready to say good bye to your attic for a long time. You'll begin to appreciate fresh air like you never did before. But as you get close to the end, take your time and make sure each roll of insulation is butted snugly up against the previous one.
This project will definitely take an entire Saturday and maybe encroach on your Sunday football games but you will get there. Keep reminding yourself that you only have to do this once and it will save you money for the rest of your life. It always helped me.