Flashing is water-resistant material fitted at vulnerable joints and openings to help direct water away from the building. It is used around details such as windows and doors and where different surfaces meet. Flashing can include formed metal, self-adhered membranes or liquid-applied products, depending on the detail. It must connect properly with the surrounding water-resistive layers.
During home addition planning, ask how new openings and junctions with the existing home will be flashed. The selected products and installation sequence should work together as a complete detail, rather than as separate patches. Much of the work may be concealed by siding or trim when finished, so keeping product information and photographs before it is covered can make future inspection or repair easier.