Ok,

Just putting this out there as I am toying with the idea of insulating my garage. It's a 3 car attached garage, but 2 walls are exterior and unisulated, but they are sheetrocked. When we purchased the house, it was too far along in the build process to have them insulate it.

My question is this. Is there any "easy" way to insulate a garage that is already sheetrocked? I"m in Minnesota and when it's -15 out, well, the garage @ -1 isn't really getting the job done. I openly admit to knowing very little about insulation installation, especially in a situation like this. Are vapor barriers needed? Is blown the way to go? Am I just flat out of luck or just cost prohibitive?

Any thoughts or ideas would be great

 

One of my neighbors blew his. They had to cut small squares at the top of the wall between each rafter, then blew it in with one of the blowers from a rental place. Afterwards, he had to patch all the holes. It took him about a day to do it (had 1 person helping). I have never checked into it personally because I built my house and had the garage insulated at that time.

Do you have the insulation on your garage door? I have not done that yet, but have heard that helps more than having the walls insualted.

 

an easy way I can think of is 4x8 sheets of rigid foam placed against the sheetrock, til you figure out a better way. I'd say blown like the pevious post says would be the most feasible.

 

Check it out before doing this, as it may be against your local fire code. It is where I live. I considered covering the inside of my basement walls (formed concrete) with rigid foam, and was told that it must be covered with some type of fire-resistant material, such as sheetrock or blueboard.

 

Home depot rents the machine and sells the insulation. The only thing you have to be aware of, is fire stops in the stud bays. If your walls are finished. It won't be easy to tell. What you have to do is. Cut two holes. one in the top and one in the bottom of each bay. This insures that the insulation is filling the whole cavity. Another note is. Insulation blown in on the vertical will settle over time.
I believe they also have a low expansion foam system that is installed the same way, but not DIY friendly.

Frank

 

The FOAM used to pop the drywall right off the studs. If you do the foam, re-SCREW the board to the studs first.

 

When I built this house, I had the insulation doubled in the ceiling, and had the garage walls insulated. It is on average about 5-10 degrees cooler than the temp inside the house in the winter. The summer was a little less efficient than so far this winter, but the suns angle is directly on the door for most of the day. I do not have the garage door insulated yet, but want to do that this summer. I would say that the ceiling is the most important, walls next, door last.

 

I got the blow in stuff at Home Depot in NM when I lived there. Buy so many bags of the stuff and the machine was free rental for a day.

 

Honestly DW is cheap. I'm sitting here picturing all those holes in your top plate. What a mess, what a hassle, what a liability. If you cut one hole too big, or too close to the edge, the whole roof could splay out and bow the wall.
The right thing to do is just yank the rock off. Insulate with kraft faced, that will give you your VB and re-rock it. Super easy.
Foam board is fine, actually recommended, in a basement, but you have to be able to seal it. Air will move through cracks pretty easy, so in a bsmt, you glue it to the walls and tyvek tape the seams, and urethane caulk the floor joint. Its easy to put between studs but in practice is not very efficient and detailing it to make it that way would be a labor killer.
Your garage door, the answer is going to depend a little on the model, so best answer there is call the installers and inquire. Some have retrofit insulation kits which are precut and pretty much go in with ease. They will cost as much as your uninsulated door did new. Some don't. If your door doesn't, to insulate it, get a different door.
While you have the walls open, have your sparky wire 220 out there and hang a small heater so once you've insulated it you can actually heat it and use it when you want. You might also look at outlet locations. If you're going to have a bench, outlets up about 4 ft are much more convenient. Depending on your local coding, you might have darn little in the way of outlets to begin with.

 

[QUOTE=TwelveAlpha]Honestly DW is cheap. I'm sitting here picturing all those holes in your top plate. What a mess, what a hassle, what a liability. If you cut one hole too big, or too close to the edge, the whole roof could splay out and bow the wall.

What you do is cut a small hole in the rock, just below the top plate.

Frank

 

Right, but it was mentioned to go in the attic and bore the top plate, which is why I said that. Besides, the fireblocking he doesnt know about, and outlets . . . its just two walls. Couple hundred bucks to do it right.

 

Good point

Frank

 

I did my garage. Had a pro blow in the walls and attic. They bored a 1" hole at the top, and 12" above the bottom plate. I also have a Martin heavy duty door. It was done in about 3 hours with the patching and everything. To pull down all the drywall would put the garage out of service for a little while and it's no fun working in 0 degree weather. You could wire by opening in the attic and putting hole at the top plate and openeing the walls at the fireblocks. Do this before you blow in insulation. My garage feels about 20 degrees cooler in the summer. Since we have mild winters here I don't think i've felt colder thay 55 in the winter or 90 at the worst in the summer. If you have a large window make a close fitting drape out of a packing quilt helps alot too.

 

Im a general construction contractor in my day job and the BEST way is to rip the drywall off, spary foam the cavities, then re-rock. But for 99% of folks that is too much work and messy-esspecially since if this is like most garages and has stuff already hung on the walls.


Next option is rip off sheetrock and install either kraft faced-it's upto you if you want to staple the kraft paper to the stud faces, or like "insutry standard anymore" leave the stud faces untouched and staple the kraft paper to the sides of the studs, spin off would be to install unfaced and then install 6mil poly over that and then sheetrock-DO NOT use both kraft faced and a poly vapor barrier-this will trap moisture and will lead to condensation/mold in the future.

Or, the easy way out. buy the losse fill insulation, rent the blower for free. Cut a hole big enough for the hose to fit through without the tapered aluminum cone tip which clogs waay to easily waay too frequently. Cut a hole right below the top plate and also mid wall. Start filling at mid wall first, this ensure the lower wall cavity gets filled completely, if you try to fill the entire cavity from the top only the insulation will bridge and only fill from the bridged area up...not good.

For the guys with excessive heat in the summer, look into how the attic is vented, make sure you have enough vent (enery star is 1sqft of vent for every 150sqft of attic space) Not enoguh, improperly installed, or non-existant venting is 90% of the problem with excessive heat build up during the summer months.

 

What is on the outside of your house? If vinyl siding and osb/plywood sometimes it is easier to take that off, or cut a 2 foot section across the middle and put batt insulation in from outside and put your sheeting and vinyl back on. The batt insulation can be pushed up and down in place with a pole. Done this a few times on older houses with plaster.