Flashing

The vertical or near-vertical continuation of the roof waterproofing above the general roof level at abutments, parapets, rooflight kerbs and penetrations. UK guidance calls for upstands of sufficient height above the finished roof surface, terminated with a flashing or capping so water cannot get behind the membrane.

A low wall extending above the roof line at the edge of a roof, balcony or bridge. Parapets require careful waterproofing, with membrane upstands, damp proof courses and copings, because they are exposed on both faces and are a common source of water ingress.

A detail at a roof edge or gutter that projects the waterproofing beyond the supporting construction so water drips clear rather than tracking back under the covering. In felt roofing a welted drip turns the membrane down into the gutter, while preformed metal or GRP trims perform the same function in other systems.

A raised frame or upstand constructed on a roof to support and weather items such as rooflights, smoke vents and plant, lifting them above the waterproofing plane. The membrane is dressed up the kerb and the unit itself or a flashing caps the top edge.