Insulation

[rallynova]

I am insulating my garage with faceless insulation.(stuff without paper.)

My question is do I need to put a vapor barrier like palstic on the walls or is that for inside the house only.

 

[shanker]

yes... the Kraft Paper is the vapor barrier


I'll be doing the same thing here shortly as soon as HVAC and Electrical are done (Attached Garage), then going over it with 6mil plastic and tape all seams well with the special vapor barrier tape

 

[rsa]

I am insulating my garage with faceless insulation.(stuff without paper.)

My question is do I need to put a vapor barrier like palstic on the walls or is that for inside the house only.

This post has references that might help.

 

[oilslick]

I skipped it and plan to paint with vapor barrier approved. I figure with plastic under the slab and only heating while present it was a unnecessary and just another cost driving the cost of my build over budget , maybe I am wrong but willing to try anything to save a few bucks when I can.

 

[twocoda]

if your garage is attached to the house make sure you do not vapour barrier that wall in the garage...it will already have a barrier on the interior side and you dont want to create a double barrier...in our area it isnt code to even insulate a garage let alone vapour barrier it...but we always do anyways...R13 for the remaining three walls that are exterior to the elements and R13 in the garage ceiling...

 

[Steevo]

I did mine the same way.
Unfaced R21 batts with vapor barrier over it.

 

[1938flatty]

I would like to do the same but how do you keep the insulation from eventually sliding down or saging inside the wall cavity?

 

[Steevo]

You'd have to repeatedly drop the building from several feet off the ground to make the insulation shift downward in the stud cavities, given how tightly it fits and the natural friction between the glass fiber batts and the wood studs.
In my case, there are also lots of staples sticking through the OSB sheathing where the vinyl siding was fastened from the outside, creating thousands of spikes that will keep insulation from moving, assuming the tight fit between studs and pressure from sheet rock aren't enough..
In real life, it won't move at all.

 

[1938flatty]

Thanks, lots of great points.

 

[bglad]

Should the ceiling have a vapor barrier also?

 

[nwav8tor]

yes!

 

[Angelfire]

This post has references that might help.

Read this link. There aren't many that require a true class 1 retarder (ie plastic). Determine your climate zone and use a retarder to match.