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Garage Attic Insulation

17 years ago

I can't seem to figure this out. I have a 2-car attached garage with accessible attic. About 30% of garage attic is above living space. This section of the garage attic has insulation blown over it. The remaining 70% of the garage attic is uninsulated and is not over any living space (it is over the unheated garage).

Is there any benefit to insulating the remaining garage attic over the unheated area? If so, are unfaced batts ok? The attic is properly ventilated and the garage is insulated on three sides (attached to house) and the garage door is insulated.

Thanks!

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Comments (4)

rredogg
17 years ago
redglide,

So far as the insulated area in the attic, it may have been in the building code that all walls and ceiling that are adjacent to living quarters are required to be insulated. To continue on with insulating the rest of the attic you could use that blow-in cellulose insulation that you can get at Home Depot along with renting the blower for about 20 bucks a day. It's easy work and better then working with reqular insulation.

If you do choose to go with the blow-in cellulose just make sure to keep you soffit vents clear in the attic to prevent condensation which leads to rotting of the roof.

Best of luck, rredogg
redglide
Original Author
17 years ago
OK. Since the adjacent walls to the house are already insulated, what am I gaining by insulating the remainder? My garage is not conditioned (heat or cooling) and as I said, there is no living space above. True, I may keep the temperature swings in the garage itself lower, but is there any real benefit here? Isn't it possible that once the heat of summer or cool of winter "sinks in" to the garage (which it will, albeit more slowly with full insulation) that it could actually them take LONGER to remove the heat (or cold) BECAUSE of the new insulation?

My real hope here is that by completing the attic insulation, I would somehow get a benefit to the adjacent living spaces from the garage walls. Thus, I am still not quite seeing all the ins and outs of this.

Also, why the blow-in type? Wouldn't R-30 between the joists work nicely? If yes, I'm thinking unfaced since there is no "heated space" to place a vapor barrier toward. Any more thoughts are greatly appreciated.
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davidandkasie
17 years ago
my garage is insulated with teh same roll in insulation used thru the rest of the house. on top of this is another few inches of blown insulation. this made it really nice this past week when i was using the garage as a workshop to strip and paint doors. temps outside were in teh 30's to 40's, but in the garage was a nice 68!

if you only use it to park your vehicle, then no need to insulate. but if you work out there, then by all means do it.
bus_driver
17 years ago
Our unheated attached garage is fully insulated with 6 1/2" fiberglass in the ceiling, 3 1/2" in the walls. It makes it much more comfortable. The Summer highs and Winter lows occur only for a few hours each day. The insulation helps keep the temperature at nearer the average for each day.

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