insulation in garage attic, vapor barrier needed??

[royalton10]

I am getting ready to have a contractor do the blown in cellusose in a garage that is 15 years old, drywall on ceiling, no vapor barrier was installed. Walls are 2X4 with fiberglass batts. Building is 44' wide 26' deep.

The contractor is going to blow in the insulation to either R-38 or R-48 on top of the drywalled ceiling. Drywall was installed years ago and was poorly taped, that was redone and finished this fall.

I have been holding the contractor up by doing some extensive rewiring in the attic and am almost done. Now I am doing some additional thinking.

My question is - Do I need some kind of vapor barrier or will I be OK with cellusose resting on top of drywalled ceiling? Do I need to rethink this plan?

Thanks!!

 

[D KRAGER]

You are going to get people saying yes and no on this question. Try searching I think there was a debate here a while back.

I'm getting ready to blow some and I'm not going to use a vapor barrier. Some cellulose manufacturers don't recommend it. (OK everyone that is **** about vapor barriers chime in and say I'm wrong, cause I know you will.)

Think of old houses that were built without insulation and no vapor barrier. Later on everyone blew insulation in the walls and attic.

 

[walrus]

How much ventilation do you have above the blown in? I'd seal every penetration into that area, plumbing , wiring etc holes should be caulked tight. Warm moist air ruins insulation quickly if allowed to go thru dew point

 

[jerry j]

Forget the vapor barrier unless it's going to be a car wash....

 

[kah68]

If you are already boarded up then I would probably not worry about it. Different insulations have different requirements, consult your insulation contractor and your local building official.