Air-Permeable Housewrap Protection
wranch
| Posted in General Questions on
Any ideas for a material that is an air permeable, inexpensive, UV-weather resistant barrier?
It sounds like an odd question but I am looking for something to protect my self adhered house wrap during phased portions of my project without impacting its vapor permeability. I might also provide the benefit of a breathable layer between the poly faced exterior foam and house wrap.
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Replies
MW,
Here in rural NH, Tyvek is one of the most popular choices for exterior cladding. Vermont is slightly more classy with their fancy Typar.
If you are looking for something more air permeable then perhaps a cheaper, perforated WRB will work.
Obviously these WRBs are only rated for a couple month's exposure. But I suspect it will be more than enough to keep the sun off of your SA WRB.
Rick,
Thank you for your suggestions. Also considered roofing felt for being highly affordable but the perm rating is lower than expected, around 5 or so. The mesh like you use for blow in cellulose also crossed my mind but not sure how much protection that would provide or how long it would hold up outside.
Michael
Michael,
I think you want something vapour, not air-permeable. Regular building paper goes from 0.5 to 60 perms depending on how damp it is. The big problem is keeping it on the house in winds.
If you want something to block UV from getting to your “real” housewrap, but is vapor open (and air permeable), then I’d recommend using some garden fabric. Garden fabric is a type of geotextile material normally used to keep weeds from growing in garden. There are several types available (one looks like a plasticy type of canvas, the other looks more like a very lightweight felt), usually rated for the number of seasons they can be expected to last. All of these (except for the black polyethylene sheet kind, you don’t want that) will allow moisture to pass through as well as some very limited air movement. You can get this stuff in the garden section of box stores and it’s not terribly expensive.
Bill
Thank you everyone for your replies and ideas. I'm leaning towards minimally tacking up the cheapest housewrap I can easily find for temporary protection to be removed before foam install or using Tyvek Drainwrap and leaving it in place.
If it helps anyone else, I found a comment on here from Martin about combined perm ratings. In theory, you can calculate the combined rating. To know for sure it needs to be empirically tested.
Perm ratings, ASTM E96 Method A, Henry VP100 - 33, Tyvek Drainwrap - 36.
1/((1/33)+(1/36)) = 17.
Michael