DIY Chatroom Home Improvement Forum

DIY Chatroom Home Improvement Forum (http://www.diychatroom.com/)
-   Building & Construction (http://www.diychatroom.com/f19/)
-   -   Unfaced insulation above garage (http://www.diychatroom.com/f19/unfaced-insulation-above-garage-72313/)

BlueBSH 05-28-2010 07:18 PM

Unfaced insulation above garage
 
I have a garage that has only attic space above it... I want to insulate the ceiling, mainly for sound reduction... the walls are already insulated R-19 but the ceiling has nothing (not even a vapor barrier) just drywalled and painted.... a lot of sound comes in from the attic from the road about 20 ft away... is there any problems with insulating it with R-30 unfaced insulation? I can't seem to find faced R-30 anywhere around me... lowes and the local building supply stores dont carry it... just unfaced R-30... this will never be a living space, just an attic with a plywood decking on it...

so my plan was to have it like this

1)Drwall ceiling in garage.. (already there
2) R-30 unfaced insulation stuffed into the 2x10 ceiling joists cavaties
3) 23/35 OSB or plywood decking so we can store some stuff up there

any problems you guys see with this? or do I absoulty need to get a vapor barrier in there?

TheCamper 05-28-2010 08:16 PM

Along with proper attic ventilation the vapor barrier helps to keep the insulation dry. Damp insulation doesn't insulate as well as dry insulation. e.g. when your clothing gets wet in the winter you get cold pretty quick and the damp clothing wicks away the body heat. So in your situation where you are not conditioning the garage space and you are likely not generating moisture (no showering, cooking or house plants, just some breathing) in the garage, I think you can go with the unfaced insulation. good luck with the project.

Ron6519 05-29-2010 03:39 PM

For a 2x10, you should put in R-25 as it's made for the joist size. Compressing an R-30 has no advantage. If you want a vapor barrier, lay a 6 mil plastic in the joist bays before you install the batts.
Ron

Scuba_Dave 05-29-2010 03:43 PM

R30 is also made for 2x10 joists - 9.5"
R38 is for 2x12 joist

R25 I see listed as 2x8 - 8" thick ?

BlueBSH 05-29-2010 08:30 PM

Quote:

Originally Posted by Ron6519 (Post 448569)
For a 2x10, you should put in R-25 as it's made for the joist size. Compressing an R-30 has no advantage. If you want a vapor barrier, lay a 6 mil plastic in the joist bays before you install the batts.
Ron

The John Mansville insulation at lowes here says R-30 is for 2x10 joists... says its 9 inches thick... must be higher density then R-25 at the same height

BlueBSH 05-29-2010 08:31 PM

Quote:

Originally Posted by Scuba_Dave (Post 448570)
R30 is also made for 2x10 joists - 9.5"
R38 is for 2x12 joist

R25 I see listed as 2x8 - 8" thick ?


I can get R-38 faced, but yeah, that is way to thick for this application since it would be compressed....


which brings up the question, does anyone make a faced R-30?

Scuba_Dave 05-29-2010 08:34 PM

I installed R30C faced for a cathedral ceiling
I have an insulation store about 2 miles from the house
Its all they do
They can get just about anything made

Big box may be able to order it

BlueBSH 05-29-2010 08:36 PM

Quote:

Originally Posted by Scuba_Dave (Post 448657)
I installed R30C faced for a cathedral ceiling
I have an insulation store about 2 miles from the house
Its all they do
They can get just about anything made

Big box may be able to order it

Was yours from a specific mfg like owens or johns? or some other company? just wondering who made what you got to see if any of the local people can order in what I want

Scuba_Dave 05-29-2010 08:44 PM

Owens Corning - I bought it at HD actually

BlueBSH 05-31-2010 03:30 PM

Well I was able to find R-30 batts that are Kraft faced... wish we had rolls since they are generally 25 ft long at R-30 and that would of been a perfect length, but I guess batts will do also :)


All times are GMT -5. The time now is 12:47 AM.


Copyright 2003-2014 Escalate Media LP. All Rights Reserved