Insulating and Finishing Ceiling

[matt151617]

Due to some bad calculations, I have about 20 rolls of R30 unfaced fiberglass left over from my house; the perfect amount for the ceilings of my garage. The garage is unfinished and not insulated; I only occasionally run a propane heater when I'm working out there.

I figure I might as well finish the ceiling while insulating, since the insulation will need to be supported anyways. I plan on eventually finishing the walls with OSB but probably won't insulate them (too expensive).

- Do I need to install a vapor barrier between the insulation and the ceiling material? There's a lot of debate about this; I park cars in the garage in the winter and there's melting snow so a lot of moisture.

- Should I use drywall or OSB? Drywall seems easier to paint, OSB seems easier to hang but is more expensive ($13/sheet vs $10 drywall). Also since it's a ceiling, can I get away with thin 1/4"?

 

[darcyh]

Hello:

Yes, you should install a vapor barrier.
1/4 inch material will probably sag.
Drywall will be more fire resistant than OSB.
For the couple of hundred it will cost I'd also insulate the walls when you decide to cover them.
Regards
Dave

 

[Spudland_Dave]

Due to some bad calculations, I have about 20 rolls of R30 unfaced fiberglass left over from my house; the perfect amount for the ceilings of my garage. The garage is unfinished and not insulated; I only occasionally run a propane heater when I'm working out there.

Hmmm.....Sounds like your calculations were just about perfect to me

What to use is up to you....Hours & Days of reading about OSB vs Sheetrock on here.
Personally, I'd strap the cieling 16" OC and install whatever cieling material you want. 1/4" Sheetrock will probably be too thin no matter what, but you probably could get away with 3/8" if you REALLY Wanted to. Seeing as how the cost of thinner sheets is the same if not higher then 1/2" I'd just use 1/2" and not worry about it.

 

[deter]

no vapor barrier. Use 5/8 drywall for the ceiling. Its well worth it for the rigidity and fire-resistance. Also, whether you finish it or not, its already white so it will be much brighter than OSB. Drywall is much easier to hang too

$.02

 

[DPelletier]

1) yes use a vapor barrier

2) insulate the walls, it's cheap

3) 1/4" is way too light and will sag.

4) If it's an attached garage, use drywall for the fire separation (usually 5/8" type X)

Dave

 

[DPelletier]

Oh and IMO, moisture control should be more proactive than "let it percolate through the walls". I put a small (cheap) exhaust fan on a humidistat to exhaust moist air as required but honestly, so far I have yet to exceed 54% relative humidity so it hasn't been needed.

Dave

 

[pfarber]

I want to meet this mythical person having so much trouble with water in his garage.

 

[klogan121]

See attached pic, how about steel on the ceiling? Its a little more costly, but there is no finishing or painting needed once its up!! It reflects light great too! I love it!

 

[rsa]

You're climate zone 6. You need a vapor retarder (preferable), but a vapor barrier is acceptable. Since your insulation isn't faced, try a vapor control primer/paint. Creating an air barrier layer at the ceiling is critical—those small air leaks can carry lots of moisture.

See this post for specifics and definitions.

 

[Fun pain]

the guy above this post is what I would say...

Science and experience says, in zone 6 like you and me (ohio) vapor "barrier" can run us into trouble with mold in the summer and condensation issues

 

[matt151617]

Thanks all for the help. Looks like I'll go with one of those vapor resistant primers and some faced R13 for the walls. The garage is detached so drywall vs OSB doesn't matter to me. I may go drywall since it's easier to paint.

 

[matt151617]

One more question... does the green water resistant drywall count as a good vapor retarder instead of using paint?

 

[vartz04]

Osb isn't bad to paint. I got good coverage with 2 coats of exterior latex paint using a 3/4 inch nap roller.

 

[Ck1]

You're climate zone 6. You need a vapor retarder (preferable), but a vapor barrier is acceptable. Since your insulation isn't faced, try a vapor control primer/paint. Creating an air barrier layer at the ceiling is critical—those small air leaks can carry lots of moisture.

See this post for specifics and definitions.

Thank you for your post. I read the linked post and the links.

I am in western lower Michigan (zone). Stick framed barn occasionally heated. I am using metal on the ceiling. From the links it appears that I should not be using any vapor barrier such as 6mil pe. Correct?

 

[rsa]

One more question... does the green water resistant drywall count as a good vapor retarder instead of using paint?

I doubt it. The first one I found that listed the vapor permeability was American Gypsum M-Bloc® Type X which had a permeability of 27 (ASTM E 96).