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djjc76 07-06-2006 10:38 AM

Garage Insulation
Fellas, my garage gets blazing hot. I just moved in to my new home. There is no drywall whatsoever and I am thinking this is my golden opportunity to put some insulation.

Where should of place it and what kind do you all suggest? Thanks!

astroracer 07-06-2006 10:48 AM

In the walls and ceiling. Go as thick as you can depending on what the walls and ceiling are framed with. Fiberglass bat is probably the most cost effective.
Do any additional wiring before you seal the walls up. :thumbup:

Kevin45 07-06-2006 11:03 AM

Yep...fiberglass batt. At least R-19 in the walls and R-30 in the ceiling. With the garage insulated well, you keep it shut up with minimal light coming in, you go out into the garage on an 85 degree day, it will feel like it is air conditioned. My garage is well insulated and on a hot, humid day, is probably 10-15 degrees cooler until I open a door or two up. Besides that, the insulation will pay for itself in a year or two depending on how much time you spend in the garage. And with the high prices of heating nowadays.....


rj57 07-06-2006 03:52 PM

I insulated my barn shortly after it was finished in 1985. I used the 3" batting (an R-19 I think?) in the walls and the 8" attic blanket (R-30) between the upper & lower sections. It feels like the barn has A/C on hot days if you keep the doors and windows closed to keep the heat out.

If I leave the stairs open you can feel the heat radiating down from upstairs so I keep the upstairs closed off from the main floor.

I want to do the garage at my girlfriend's house when I can. I know it'll make it a lot nicer out there for me.

matt167 07-06-2006 04:03 PM

fiberglass batt is the cheapest but you could get the R32 foam board insulation that has the foil on it, R 32 I think is 2" thick I think, cut it to fit in between the studs and it would be easier to put up. wish I had a real garage, I'v got a portable tent garage, that is a light wave oven in direct sunlight, awsome in the winter ( 70* daytime in the sun ) but it's 10-15* hotter in there than outside year round, and It's blazing in there in the summer with the door closed, working on my '51 Chevy is sometimes more of a chore than a hobby I enjoy but, I keep my mind on the finished product and that keeps me going on it.

1ownerT 07-06-2006 04:25 PM

The R-value will depend on the wall thickness, and the manufacture of the insulation.
3 1/2" R-11 to R-15
5 1/2" R-19 to R-21
You should use a vapor barrier, walls and ceiling.
When I built my garage I used 3 1/2" R15 in the walls and the first layer in my trusses was the same with 8" R-30 on top of it giving me R-45 in the ceiling. If at all possable you should vent the space above your ceiling, helps to prevent heat build-up.

adtkart 07-06-2006 08:01 PM

Keep in mind that, if you insulate it, you have a "Man law" responsibility to keep it cool in there in the summer and warm in the winter. LOL

The insulation will make a difference. You have to remember that it will also keep the heat in during the summer months, if you let it get too hot in there. My garage is 34'X24', with an addition that is 24'X16'. The addition is completely insulated, and has a window AC unit in it.The AC unit is electronic, like most of the newer ones, I guess. It has the ability to keep the room at a certain temp. The thing runs very little to keep it cool. The other section of the garage would cost me a fortune to cool or heat, without any insulation in there. Even though there is a drywall ceiling in there, it gets so hot, you can feel the heat coming from it. I have just added an attic fan to cool the attic off. One day I will have the money to insulate that side. Just need to find a reason to buy insulation for the house, so I can buy too much. LOL


schnitz 07-06-2006 09:19 PM

Since I'm still trying to finish mine, I'll chime in on this....

1ownerT has it right with the thicknesses of your walls. 2x4 construction means a 3 1/2 inch batt. Nothing thicker. My garage is getting R-11 on the walls and the ceiling, vapor barrier (.2 mil.), and then 3/8" OSB over that. Pictures are in my project gallery. Somewhere in there.

Couple of things to really remember have already been listed, but I'll re-state them. First, you must adequately vent the attic to rid that area of excess heat and moisture. I know theres guides on how much venting you need, but if you go to a local Home Depot, Lowes, or Menards, they can tell you how much venting you need. Just have the full garage dimensions when you go.

Secondly, before you button the walls up, best thing to do is run all the wiring you think you may need. It's a real pain to pull it back apart to run another circuit after the wall is finished. Trust me on this. I've been there, done that.

Lastly, you did not mention if your garage is detatched or not. If it is attatched, you may need to have drywall put up between the house and the garage to meet your local building codes. Most areas that I've heard have that as a requirement in new construction.

In a while, Chet.

garyroushkolb 07-07-2006 05:19 AM

r-30's worth the extra
My shop is a metal building an I have r-30 in the walls and ceiling. The inside walls were done with siding metal also. There is an extra benefit of the r-30, it really makes the place quiet to work in.
I have floor heat which is the best thin I have ever done as it costs little and keeps the place warm and equipment also. Summer I keep the door closed and it place keeps cool. I was going to use AC but didn't need it or the expense, I just use a dehumidifier.
The thing I would do different is insulate next to the roof and then the attic storage would stay warm in the winter, I put the insulation between the ceiling and the attic. I use an exhaust fan in the attic that comes on at 85 degrees, and it runs in the afternoons.

66ImpSS396 07-07-2006 06:25 AM

Something i found helpful was an exhaust fan in the garage to help remove noxious fumes from the car and the mechanic lol. it also helps remove the heat from a hot car that the good insulation will keep in the garage for a long time on a warm day. The direction my garage sits causes the prevailing winds to blow into the garage doors and trap exhaust (even from cars sitting on the pad outside if the door is open) and chemical fumes in the garage, without the fan it takes a long while to clear out. Also lots of lights (us old blind people can't see anything without them).

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