Shingle lapping is the core rule of water management: every membrane, flashing and building wrap is lapped so water running down the wall passes over each joint, never into it. Upper courses go over lower ones, sill pan flanges over the wrap below the opening, and the wrap above a window over its head flashing. The rule is checked on every inspection of a WRB or flashing.
Keep everything shingle lapped, pan flange over the wrap below and the head flap of wrap down over the head flashing.
Also heard as
- shingle-lapped
- shingling
- shingle fashion
Related terms
Reverse lap
A lap installed the wrong way, with the lower layer over the upper, so water is channeled behind it.
WRB
Water-resistive barrier, the layer behind cladding that sheds water that gets past the outer skin.
Flashing
Thin sheet metal or membrane installed at joints and interruptions in a wall or roof to direct water back outside.
Strip-in
To seal the flange of a flashing or fixture to the surrounding membrane with an overlapping strip of tape or sheet.