Wall vapor barrier
Wall vapor barrier
(OP)
I am building a new house. The first floor has a brick veneer and the second floor has a wood panel type exterior.
My question regards the vapor barrier. On the first floor the insulation contractor installed a insulation without a backing and a visqueen (spelling?) vapor barrier. On the second floor he installed the insulation with a paper backing type vapor barrier.
The reason he gives for not installing a visqueen vapor barrier on the second floor is that the insulation might sweat and get wet.
Does not sound correct to me. What is the opinion of this forum? Should there be a visqueen vapor barier on the second floor also?
My question regards the vapor barrier. On the first floor the insulation contractor installed a insulation without a backing and a visqueen (spelling?) vapor barrier. On the second floor he installed the insulation with a paper backing type vapor barrier.
The reason he gives for not installing a visqueen vapor barrier on the second floor is that the insulation might sweat and get wet.
Does not sound correct to me. What is the opinion of this forum? Should there be a visqueen vapor barier on the second floor also?





RE: Wall vapor barrier
You certainly need a vapor barrier for the 2nd floor [building inspector would notice if missing], but it doesn't have to be PE film. The advantage of using PE is that it comes in large widths & hence is also good at stopping cold air infiltration at any gaps due to insulation settling or installation of conduit or plumbing.
Not sure exactly what 'paper backing type vapor barrier' you have on the 2nd floor. I presume you are using roll-type fiberglass insulation between wood studs. The aluminum foil backing is perhaps best, but plastic-coated paper is also OK. For both, make sure the the stapled flanges are overlapping, flat & tight to the studs – you can add extra staples.
“The reason he gives for not installing a visqueen vapor barrier on the second floor is that the insulation might sweat and get wet.” -- This is nonsense, the moisture comes from within the house. However, probably not a good idea to add visqueen over an existing vapor barrier as moisture could get trapped between the two. For additional vapor barrier protection, e.g., for bathrooms or kitchens, some aluminum paints are very good & keep moisture out of drywall or plaster altogether.
RE: Wall vapor barrier
He used this type of insulation also in the wall between the living room/laundry room and garage for the same reason I guess.
The point is why did he not use a visqueen type vapor barrier on the second floor instead of the plastic paper.
At this point all that could be done is to install the viqueen over the plastic paper vapor on the second floor. Do I need to insist that he add the visqueen?
Like I said it does not seem consistant.
RE: Wall vapor barrier
I'm thinking that there should be a layer of tarpaper between the brickwork & the sheathing. Thus, it's more important to have a tight vapor barrier for the 1st floor walls, as it is much more difficult for any moisture to egress.
RE: Wall vapor barrier
Since I am in my late 50s this will be our retirement home and with the soaring energy prices the objective is to get a energy efficient home.
My background has more to do with pipe insulation and metal building insulation where noise is the primary concern so I feel like I am sorta out my area on this one.
RE: Wall vapor barrier
RE: Wall vapor barrier
If you build a wood home in Florida, don't worry about the moisture -- the termites will consume it!!!
You make a good point. The air conditioning causes a dehumidifier effect, with the walls as condensers.
Last time I was in Florida, seemed like mostly poured & block concrete homes.
RE: Wall vapor barrier
Thanks for the help. BTW, I live in OK where it normally gets cold enought in the winter to kill all the bugs. However this winter we have had only a few weeks of cold weather so there may be a price to pay next summer.
RE: Wall vapor barrier
You hit the nail on the head with the termite comment. The number of homes damaged around here each year due to termite infestation is staggering. Most homes are block/stucco. Even though the exterior does not represent a good meal, these critters always seem to find their way into the interior walls and have an absolute feast. I can tell you first hand, getting rid of termites is an expensive proposition and your insurance company wants no part of it.
Mike
RE: Wall vapor barrier
RE: Wall vapor barrier
Too late for you I'm sure but I am seeing more and more Tyvek wraping of outer framing prior to veneer applications.
These are pictures I have seen in the Southwest and West so take it for what its worth where you are.
My thoughts are seal the walls and ventilate the space within.
pennpoint
Best regards
pennpoint
RE: Wall vapor barrier
For northern climates they go on the room side of the insulation
RE: Wall vapor barrier