An upstand is the section of a waterproofing membrane, lead flashing, or roof covering that is bent upwards to run vertically against an adjoining surface, such as a wall, skylight, or parapet. It prevents water from pooling and seeping under the horizontal roof deck at the junction. A separate piece of counter-flashing is usually installed over the top edge of the upstand to completely seal the joint.
Make sure the upstand on the flat roof membrane goes at least six inches up the brickwork.
A common failure point on flat roofs is an upstand that is cut too short; most codes require a minimum vertical height of six inches to handle splashing and snow buildup.
Related terms
Apron flashing
A piece of sheet metal installed at the base of a wall or chimney to shed water onto the roof.
Step flashing
Overlapping L-shaped metal pieces used to seal the joint where a sloped roof meets a vertical wall.
Built-up roof
A flat roof covering made of alternating layers of bitumen and reinforcing fabrics.