We are installing new vinyl windows in a 100+ year-old-house. We are leaving on the wood underlayment where possible or replacing with plywood as needed. We are adding 1/4 inch foam board for extra insulation and then tyvek to seal it all. When we started putting the windows in, we did not have the 1/4 inch foam board, hence did not put it behind the windows - only sealer tape and tyvek as appropriate. Now we are installing a patio door and my husband is putting the 1/4 inch foam behind the flange of the door. The flange is for the vinyl siding and I believe it will accommodate the 1/4 inch pink foam as well (plus sealer tape and tyvek properly installed. Our question is - should the door and windows be installed over the 1/4 inch pink foam or should it be installed after the windows are in and put in the flange area??? Then, of course, properly seal all with sealing tape, tyvek, etc., etc.
ok,the drainage plane starts just under the flanges,the flashing or membrane needs to over lap the foam allowing water to drain away on top of the foam instead of behind it at the bottom of any openings
the flanges don't necessarily need to be built out the foam thickness as long as this drainage detail is followed
hopefully this pic can give you an idea
you need to be very careful you don't inadvertently cut the tyvek when fitting the foam
Last edited by Tom Struble; 08-18-2011 at 05:04 PM.