Another insulation thread

[mristine]

Looking for suggestions here. Minnesota. Attached 3 car garage. 2x6 walls are insulated. I am wondering about the ceiling. The ceiling is sheetrocked. So there's an attic space up there with no insulation. The attic above the living space is insulated, they just didn't take the time to blow it over the garage too.

The ridge on the garage does not appear vented, nor are there vents in the roof.

I am thinking rolls of unfaced r13 fiberglass.

Do I need a vapor barrier?
Do I need to vent?

 

[Bolson32]

Do I need a vapor barrier?
Yes, there isn't one? Maybe some of the other guys have some ideas on how best to do this after the fact.

Do I need to vent?
Also yes, you should anyway.

Just spit balling here, but since there's no vapor barrier above the sheetrock, couldn't he just put one above the ceiling joists and blow cellulose on top of that? Would have to be careful to get seems stapled up right but I would think this could be done.

And I'd blow a **** ton of cellulose, as it's so easy to do. 100x easier than unrolling batts. R13 won't get you much with fiberglass up in our neck of the woods. What's it going to be used for??

 

[Falcon67]

The attic - I assume - it open so if you have soffit vents air should move through the garage attic space to other vents.

I did not use a vapor barrier in my shop, just laid R13 blankets between the joists. It's not a continuously conditioned space and there is no bath, showers, cooking or constant human occupation. I'd buy kraft faced rolls and just get after it.

 

[The Cobbler]

is the garage open to the main house attic? if so you probably have enough venting.( I assume the house is vented?
if it's sealed from the house you need vents.
vapour barrier in a garage gets opposing thoughts . yes or no.. either will be fine IMO
if you're going to insulate, go more . r13 is on the very low side for ceilings.
pay for insulation once, pay for heat everytime you turn it on

 

[mristine]

is the garage open to the main house attic? if so you probably have enough venting.( I assume the house is vented?
if it's sealed from the house you need vents.
vapour barrier in a garage gets opposing thoughts . yes or no.. either will be fine IMO
if you're going to insulate, go more . r13 is on the very low side for ceilings.
pay for insulation once, pay for heat everytime you turn it on

Yes, the garage attic is open to the house attic. The house was built in 1992 and is vented. I was just up there and there is a 3/4 inch space at the ridge (no sheathing for the length of the ridge that is 3/4 inch wide.) Maybe there's those special venting ridge shingles up there (to use the technical terms )

I'd like a vapor barrier, but I am not going to tear down sheetrock to do it. No way, no how. Maybe I'll have someone come in and blow a bunch of insulation up there.

 

[Bolson32]

Then you're fine. I'd just do it myself if you're doing cellulose. Staple some soffit baffles in there, rent the machine and get to work. It's stupid simple. I had two buddies help me and we prepped and did my house, which has a very shallow hip roof(annoying to prep) in about 4 hours. A garage would be easier yet, let alone one that doesn't already have insulation.