Flashing

Water finds every gap. Flashing gives it a path out. Installers lay it at the sill, up the sides and over the top, lapping each layer like shingles so water runs down and out. Self-adhesive membranes and metal pans are common.

Poor flashing is a common cause of water trouble around a window. That is why installation matters as much as the product. Ask your installer how they flash the rough opening, how they seal the corners and how they handle the sill. A sloped sill pan is a good sign. For a full overview, read our guide to planning a window and door project.