Temporarily for a few months — Tyvek wrap or foam or both to protect a house?
GBA Editor
| Posted in General Questions on
I am having old asbestos shingles removed from my house. The roof is fine. The outside house walls will be then bare wood.
I am submitting docs to the Bldg Dept for permits to do a renovation project in a few months. What should I do to protect the house temporarily. Do I just put up Tyvek wrap? Do I do Tvyek wrap and some sort of foam?
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Replies
Maria,
If all you want to do is provide temporary weather protection, all you need is Tyvek.
According to DuPont, "Tyvek HomeWrap and Tyvek StuccoWrap, Tyvek DrainWrap, Tyvek ThermaWrap and Tyvek AtticWrap should be covered within 120 days (4 months). Tyvek CommercialWrap should be covered within 270 days (9 months)."
Before installing new siding, however, it would be a good idea to install rigid foam insulation -- the thicker the better.
Or you can use Typar.
It has a longer exposure rate-- 180 days.
Typar is also more tear-resistant.
You don't indicate your location or climate, so it may not be appropriate to recommend exterior foam. And be advised that if you use exterior foam, you will have to extend all exterior trim and/or install new door and window units at the new exterior plane.
If Maria uses Housewrap as a tempory protection for her house, then decides to install rigid foam before she sides, should she remove the housewrap, before installing foam?
Does it matter if the housewrap is under or above the rigid foam?
Mike,
Many here would probably say "no". But I would say it depends on what kind of siding and how it's applied. I generally prefer the weather-resistant barrier to be the second layer immediately under the cladding where it's easier to integrate with flashings.
But if it's also to serve as an air barrier, then the seams need to be taped and it needs to be resistant to deflection from wind pressure, which can untape the seams. If a rainscreen gap will be left behind the cladding, then the WRB/air barrier is better off sandwiched between foam board and sheathing to prevent movement under air pressure differentials (which is a requirement of the Air Barrier Association of America). In that case, the foam board serves as a secondary weather barrier and should have all seams taped.