Insulating attached garage

Well ice season ended sooner than expected so the next project on the honey do list is insulating our attached garage. I ended up finding some insulation on marketplace (factory seconds) and picked it up. It was all supposed to be faced but quite a bit of it ended up having no paper. I hung it this weekend and now I am wondering if I should just poly (vapor barrier) everything since a good portion has no face or rips/tears. What do you guys think? I am no expert here but I’m thinking that is going to be the best route. I plan on covering the walls with OSB and the ceiling in steel. Thanks for any advice!

Slabz

No reason to use poly if you are covering with steel and OSB soon.
I am not a fan of sealing moisture and potential moisture in walls, the better it can breathe will help in the long run. Unless you are worried about wind penetration, I’d save my time and money.

Consider exterior house wrap.

mark-bruzek wrote:

No reason to use poly if you are covering with steel and OSB soon.
I am not a fan of sealing moisture and potential moisture in walls, the better it can breathe will help in the long run. Unless you are worried about wind penetration, I’d save my time and money.

Mark, thanks for the reply. I should also add that I do plan on putting up a hanging heater as well. Even with the space being heated, would you still recommend not placing poly? Thanks!

Poly is cheap why skip it?

DO NOT SKIP THE POLY

Would you guys poly even over the insulation that is faced or just the unfaced stuff?

Coletrain27 wrote:

DO NOT SKIP THE POLY

If it’s faced it don’t need it. If it’s unfaced then poly it. It’s cheap and easy to do so why not do it right

Pull the facing off the existing bats and poly

Poly = vapor barrier
House wrap = water barrier

Dont confuse the 2.

No poly to let a structure “breath”

slabz wrote:

Well ice season ended sooner than expected so the next project on the honey do list is insulating our attached garage. I ended up finding some insulation on marketplace (factory seconds) and picked it up. It was all supposed to be faced but quite a bit of it ended up having no paper. I hung it this weekend and now I am wondering if I should just poly (vapor barrier) everything since a good portion has no face or rips/tears. What do you guys think? I am no expert here but I’m thinking that is going to be the best route. I plan on covering the walls with OSB and the ceiling in steel. Thanks for any advice!

Slabz

Double poly that stuff. No reason not to.

No double poly!

Eelpoutguy wrote:

Pull the facing off the existing bats and poly

This.

Epg is spot on. Do not skip the polly.

Thanks for the responses everyone. I picked up a roll of poly this afternoon. One last question.. I had already stapled the paper facing to the studs, instead of tearing all the facing off would it be ok to just slice gashes in the paper with a utility knife and poly over? Or would you just recommend tearing all the insulation off, taking the paper off the batts, and re hang them?

The paper on the insulation is a vapor barrier. Imho not very good but if it is installed correctly, then your good.
If it has cuts and holes or missing then pull the paper off and poly.
Also best to seal/caulk at the plates.

The poly helps to insure the water vapor does not enter the wall cavity,without poly a positively pressured room will force vapor into wall cavity,rotting it from the inside out.
Mobile homes with the masonite vertical siding are prime examples.Mobile home heating systems use a wild return( no return air vents in rooms)so when doors are closed,rooms pressurize,pushing moisture through the walls,bowing ,bulging or rotting exterior walls.
Vapor barriers and proper ventilation are very important aspects of building science.