I have a question about the placement of a poly vapor barrier.. I hope that someone can help.
I'm in the process of framing in some offices inside of a concrete block building. The building itself is over 40 years old, and has been repainted several times with block seal, Also the interior surfaces of the block have been painted several times as well.
The building is built on a slab( entirely avove grade), and has 8" X 24" Pilasters every 10 feet on the inside.
My plan it to frame in the new walls 1" in front of the pilasters, so that there will be some room for air movement behind the wall. this air space will be open to the area above the drop ceiling.
I'm framing the offices with 2X4's, and R13 ( 3 1/2") faced insulation to the inside. The building owner keeps insisting that I place a poly film on the back side of the framing.. as a Vapor barrier.. ignoring my arguement that this will result in a double barrier ( the insulation facing & the poly) with the insulation in the middle, and will just be providing a breeding ground for mold. Am I correct in this?
Secondly, He did say that If "I wanted to" I could apply the poly directly to the concrete block.. althought I tried to explain that this would be essentially the same thing, that the poly film would hold the moisture against the painted ( read "SEALED")block walls, and also would provide a perfect enviroment for mold growth. Any sweat or condensation on the block wall would not be able to evaporate.. and the poly film would always be wet.
I'm recommending that the area just be left open to the air.. and that the ventilation will prevent the growth of mold.. which is what he's trying to accomplish with the vapor barrier.
I Argue that the painted block will pass little , if any, mosture thru, and that the faced insulation and Semi Gloss paint in the offices will effectively prevent moisture from migrating from within the building. leaving the "void area" dry.
I'm no expert by any means.. and will gladly admit it if I'm wrong.. so someone please chime in.. Barrier or not?
Thanks in advance