Garage ceiling insulation

[Twisted Sid]

I have a 26x20 attached garage that was already finished and drywalled when I bought my house. In the summer, it gets REALLY hot in there (sometimes over 100*) and cold in the winter. I know the ceiling isn't insulated so it makes me question if the outside walls were done before the drywall went up. Short of knocking holes in the walls, I haven't investigated any farther. Basically what I'm wondering is, would I notice any difference in temp if I put down insulation batts in the attic above the garage if the walls are not insulated?

Damn it, I thought I put this in the heating and cooling section.

 

[8man]

Insulating the attic will help. It will help it stay cooler in the summer and warmer in the winter. You can have R-30 blown into the attic to help.

Many homes do not have insulation in the walls or ceiling of the garage. So the walls probably don't have any insulation. Insulating them at this time would be expensive.

 

[Kingcreek]

I don't know why anyone would go to the trouble and expense of drywalling without insulation but I know it happens. Any ceiling insulation will help even if the walls are not insulated. Try pulling an outlet or switch cover and fish a bent wire next to the box and you will probably know without knocking holes in anything.

 

[Alexbn921]

YES. You lose most of the heat through the ceiling. Walls will help, but the roof is the most important. The garage door is the second source of heat/cold

 

[internetdude]

I have close to R50 above my attached garage. I keep it nice all winter long, insulation helps like crazy. You really should insulate the walls and the ceiling to do the job right.

 

[Falcon67]

Yes, you will see a difference.

 

[jkrswld]

+1, I'm in same situation as you except my garage is a bit smaller. I did some R38 ( i believe, its about a foot thick) fiberglass bats stapled between joists. I haven't finished it beyond that, but it has helped noticeably this summer already. I finished installing it toward the end of winter and it was holding heat better for sure.

Either way, it is not like just doing the ceiling will make it cozy like the inside of the house - but it will definitely help while you add fans/heat when you're out there.

 

[Twisted Sid]

Ok, so I am trying to plan this out but, what would be better? Should I use the fiberglass batts or should I do the cellulose blown in stuff? I should mention that I do store things up in the garage attic and I have put down some 1/2 plywood for flooring up there. It doesnt cover the whole attic (mabey 3 sheet worth). Obviously all that will have to come out to do this but I plan on putting it back up there. The trusses are 2x4 also.
I also plan on doing the foam inserts on the garage doors. They face the sun until noon and the heat come right through them.

 

[over40pirate]

If the you only have 2x4's under the attic walk boards, you can only put in R13 insulation in where the plywood floors are. I would put in R30 where you don't have the plywood, and R13 under the plywood.

 

[mtmgtz]

Cellulose will fill in all the cracks better than fiberglass batt but fiberglass batt is a little easier to do to the average person. You can rent the cellulose blowing machines at the big box stores and lumber yards. It's not very hard either but you'll need someone to feed the machine while you blow it in your attic. Don't blow it over in your soffits. You'll be dusty when you're done but you won't be near as itchy as fiberglass batt.