In this application, the garage roof shingles are step-flashed against the sidewall sheathing of the house. In cold climates snow will drift and collect at the point where the garage roof joins the sidewall of the house. When the drifted snow melts, water can find its way through butt joints, knots, cracks and other spaces in the siding. The solution is to place the garage roof flashing directly against the bare house sheathing, then make sure the housewrap overlaps the step flashing. And conventional house-wrapping practices have changed.
Builders often wrap the entire house before installing windows or doors.
In fact manufacturers recommend that builders wrap over the window openings, cut an X into the window opening and fold the wrap inward. Windows and flashings are then installed over the house wrap. When I see this, I am always reminded of my leakage problem with the Gambrel. WHEN rain penetrates the siding on these homes, it too could find its way behind the window flashing and into the house. Give wind-driven rain the respect it deserves.