Will some insulation make a difference in detached garage
I want to insulate my 2 car detached garage. I have 2 uninsulated garage doors, and an open cathedral ceiling with rafters below. Eventually I would like to drywall and insulate ceiling and make an attic space above. I was planning on first to insulate walls with faced batts, drywall, and glue rigid foam to garage door panels. Something that can be left exposed for garage doors. The ceiling is clearly much more work and cost. I was wondering if I would get any noticeable difference insulating the walls or is this an all or nothing approach. I’m assuming there is a possibility that since heat rises any short of heat would leave the building. Summertime cooling would be less of an issue correct? I really could care less with ceiling being exposed aesthetically since I could still store items above. This is more for comfort, if the ceiling is going to get me minimal returns I can part with finishing it for a while.
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Unless you are going to heat or cool the space I think resources spent insulating the garages are wasted.
The wife insisted we insulate our attached garage. I find the garage is almost always warmer than outdoor both summer and winter.
Walta
Insulation will act to slow the rate of change of the temperature inside the garage with repect to the outdoor temperature, but aside from that, it won't do much if you aren't actively conditioning (heating or cooling) the garage space. If you use the garage for something like a part time workshop, insulation is a good idea. If you're rebuilding the garage already for other reasons, adding insulation makes sense because it's easy to do while the walls are already open.
If you aren't conditioning the garage, and you aren't rebuilding it for other reasons, then I wouldn't bother with insulation in the walls. If you want a ceiling, I'd drywall the ceiling then use loose fill insulation above, which will make a big difference as far as insulating goes, and it's relatively easy and cheap to do. Another option that might be easier is to use batts here. If you go with batts, I would run R19 unfaced batts perpindicular over the top of the attic floor joists, then I'd use faced (to make them easier to install prior to the drywall going up, since the facer acts as an insulation support) batts between those joists. If you have 2x6 joists here, this assembly, using high density fiberglass batts, gives you about R42. Code probably doesn't apply here in terms of minimum R values since it's not occupied conditioned space, so you want to be more cost concious based on how you plan to use the space -- if you'll only heat it a little ocassionally, the extra insulation doesn't gain you much and is basically wasted money.
Insulating the overhead door can help, but the big issue with the typical overhead garage door is that it leaks air from everywhere, and it's hard to seal those doors well. These air leaks will greatly reduce the effectiveness of any insulation you install.
Bill
Thanks Walta, I want to to heat it intermittently like when I’m working on a project or using it as a gym. It’s slightly warmer inside garage than outside, that is true. I have no problem wearing a sweatshirt when working, just looking to raise the temp faster with insulation on freezing winter days. Also want to finish walls, and cant see a reason not to throw in some insulation
The best bang for your buck will be to put good weatherstripping around your garage door and a good seal at the bottom of the door. With good sealing, you'll be able to temporarily heat the space if you need to do some work during cold weather.