Replies

1. 
   DaveRicheson | Jan 26, 2010 05:54am | #1

   House wrap stops at the soffit. No point in adding a wind. weather barrier to an area that ussualy is vented.

   If you are doing a hot roof (unvented), the foam porvides the air barrier.

1. 
   DanH | Jan 26, 2010 07:17am | #2

   There is a point to having good wind/air resistance in a vented attic, especially with fiberglass. But it's much less important than the walls.

2. 
   mike_maines | Jan 26, 2010 12:52pm | #3

   It depends on where you are and what your roof detail is. We are dealing now with persistent leaks on a house we built where the housewrap stopped at the soffit. If wind-blown rain is an issue, it's better to go with a hot roof and seal the Grace on the roof down onto the housewrap. If you have a vented roof, run the housewrap up just as high as you can.

1. 
   DanH | Jan 26, 2010 08:34pm | #4

   Certainly it would make a bit of sense to wrap a strip of housewrap over the top of the wall before setting the rafters. Then stick the top edge of the wall housewrap under that strip and tape.

   I'm sure the guys setting the rafters would cuss a blue streak, and maybe rip the stuff to shreds, but from a weatherproofing standpoint it makes some sense.

   (Of course, around here it's rare to build any house (other than some hoity-toity McMansions) without a 2-foot overhang, so blowing in rain at the top of the wall is generally not a problem.)

1. 
   JohnWalker | Jan 26, 2010 10:30pm | #5

   Thanks Dan and others.

   I can see some more information is in order. I am in Vancouver Canada and the winters are very wet and just above freezing (often). We have a long history of "leaky condos" but that includes townhouses, concrete highrises and anything else that was build in the last 20 years. There are numerous reasons but I won't go into that now.

   I attended a buiders seminar on building envelops and air barriers. For our situation they were advocating rainscreens, air-tight housewrap and sealed drywall (ie no poly vapour barrier). As best I can understand it the sealed housewrap prevents the bulk air movements through the walls (and moisture drive). With the air barrier on the exterior there is no need for a 100% impermerable air barrier on the interior. It would seem they were advocating some wall cavity drying toward the interior (which would be impossible with poly).

   So with that said the housewrap air barrier needs to be complete including the roof/attic.

   Is it possible they switch to traditional poly on the ceiling and tape it to the housewrap?

   If anyone is familar with this sealed drywall & sealed housewrap approach could you help me out?

   thanks

   John

1. 
   DanH | Jan 27, 2010 02:31pm | #6

   I kind of lost touch with the sealed drywall concept back when they were still using foil-backed drywall, making for a "perfect" vapor barrier.

   I've never seen any detailing involving sealing the ceiling [boy, had to have three gos at typing that] to the wall housewrap. Certainly it could be done, but it's a cost/benefit thing, plus the technique would be highly dependent on the attic insulation scheme.