Are we asking for trouble with our window/flashing/insulation method?
I help to build houses with a Habitat for Humanity affiliate south of Houston, TX (Zone 2A) and I would like your thoughts on how we weatherproof the homes.
We use standard 2x4 construction, with OSB sheathing. (Cavities and attic floor are filled with blown in rock wool)
Flanged vinyl single hung windows are installed as per Texas Windstorm Regulations. We do not put any window pan or any other drainage plane/ water resistant barrier in before installing window.
We do use Dow Weathermate 4" Flashing Tape over all four flanges (working upward).
Styrofoam is then applied over the sheathing, up to the window frame, covering the taped flanges.
The rigid foam is then taped with Dow Weatermate 2 7/8" clear tape. Using the same tape, the joint between the foam and side of the window is sealed.
A pressure treated 1 x 4 is framed around the windows, and then Vinyl siding is applied.
The 20” wide soffit is just 4” above the top of the window. I believe that the Flashing Tape would run above the bottom of the soffit
I am thinking that if the tape does not fail, the only way water can get behind the Styrofoam is through the window. In particular the “well” where the moving part of the window sits - water could accumulate in there and potentially leak out a corner weld on the vinyl.
I really want to keep that OSB sheathing dry, and prevent any chance for water getting access to it.
PS I read the recent article “Using Rigid Foam As a Water-Resistive Barrier” and the referenced articles, and although very interesting, don’t quite cover our situation down here.
Posted Sun, 02/16/2014 - 12:41
Other Questions in Plans Review