For those of you that put their housewrap behind the rigid foam insulation, do you leave a gap between the two, so water can drain if it ever gets behind the foam boards? If so, how much of a gap and how do u create it? Some type of drainage mat on top of the housewrap or maybe furring strips? I assume if the gap is too big it would reduce the R value of my wall?
my housewrap is regular tyvek on plywood sheathing. Unfortunately, the windows are already in place and flashed, so switching to tyvek drain wrap won’t be an option anymore.