Drywalling garage - Do I need vapor barrier

[kf4zht]

I am working on drywalling my garage. It is a below-house garage, currently walls have unfaced insulation. As far as I know there is a barrier on the outside under the siding (built in 2001)

Do I need to put up plastic as a vapor barrier before hanging the drywall.

Note this is north georgia if it makes a difference

 

[Big Blue Car]

Your climent maters where you vapor barrier goes. Rule of thumb is that the vapor barrier goes to the hot side of the wall. So in FL you would have it on the outside of the wall (under the siding), but if you are in the north say NY you want the barrier on the inside (behind the drywall).

I would say that Georgia would be considered a warm climent and would go to the outside. That being said I have talked to experts and GA is considered a gray area as you get both cold weather and hot weather.

Back to your question, I would say as long as there is a vapor barrier outside you are done. You do not want two barriers as that could cause issues and trap moisture inside the walls creating mold.

 

[pattenp]

I'm in south central va and we place vapor barrier to the heated/AC side of the wall. The barrier under your siding may just be an air infiltration barrier and not a vapor barrier. My house has the Tyvek house wrap under the siding and it's just to reduce air infiltration.

 

[cderalow]

Also, if your garage is attached, I'd personally recommend using a full vapor/air barrier system to help contain any potential exhaust gasses in the garage, and out of the house.

 

[K'ledgeBldr]

I am working on drywalling my garage. It is a below-house garage, currently walls have unfaced insulation. As far as I know there is a barrier on the outside under the siding (built in 2001)

Do I need to put up plastic as a vapor barrier before hanging the drywall.

Note this is north georgia if it makes a difference

You have a drive under/basement garage.
In 2001 the "envelope" requirement hadn't been instituted- which would have required the ceiling of the basement to be insulated. Instead, builders just insulated the framed walls of a basement. The only stipulation was the batts had to be unfaced- code requirement for combustibles.
If it were to be finished- d/wall; typical case would be faced batts and then d/wall. With that in mind, use the unfaced in the ceiling and make sure that all the floor penetrations are foam sealed before covering.

 

[kf4zht]

You have a drive under/basement garage.
In 2001 the "envelope" requirement hadn't been instituted- which would have required the ceiling of the basement to be insulated. Instead, builders just insulated the framed walls of a basement. The only stipulation was the batts had to be unfaced- code requirement for combustibles.
If it were to be finished- d/wall; typical case would be faced batts and then d/wall. With that in mind, use the unfaced in the ceiling and make sure that all the floor penetrations are foam sealed before covering.

As of right now I am not going to do the ceiling, just the walls.

From the sound of it it wouldn't be too terrible to just put the drywall up, and assume I have an exterior wrap.

I will insulate the ceiling in the future, but may not close it up.

 

[Scott65]

As of right now I am not going to do the ceiling, just the walls.

From the sound of it it wouldn't be too terrible to just put the drywall up, and assume I have an exterior wrap.

I will insulate the ceiling in the future, but may not close it up.

I would not assume an exterior vapor barrier, particularly on a garage. Many contractors will not even Tyvek the garage. I would confirm what you have, by some means, prior to making a decision.