Term Description
Base flashing (membrane base flashing)

Plies or strips of roof membrane material used to close off and/or seal a roof at the horizontal-to-vertical intersections, such as at a roof-to-wall juncture. Membrane base flashing covers the edge of the field membrane and extends up the vertical surface. See "flashing."

Cap flashing

(1) Usually composed of metal, used to cover or shield the upper edges of the membrane base flashing or wall flashing; (2) a flashing used to cover the top of various building components, such as parapets or columns. See "flashing" and "coping."

Channel flashing

In steep-slope roof construction, a type of flashing used at roof-to-wall junctures and other roof-to-vertical plane intersections where an internal gutter is needed to handle runoff. Commonly used with profile tile.


Formed metal or elastomeric sheeting secured on or into a wall, curb, pipe, rooftop unit or other surface to cover and protect the upper edge of a base flashing and its associated fasteners.


Components used to weatherproof or seal roof and waterproofing system edges at perimeters, penetrations, walls, expansion joints, valleys, drains and other places where the roof covering or waterproofing membrane is interrupted or terminated. For example, membrane base flashing covers the edge of the field membrane, and cap flashings or counterflashings shield the upper edges of the base flashing.

Flashing cement

A trowelable mixture of solvent-based bitumen and mineral stabilizers that may include asbestos or other inorganic or organic fibers. Generally, flashing cement is characterized as vertical-grade, which indicates it is intended for use on vertical surfaces. See "asphalt roof cement" and "plastic cement."

Kick-out flashing (diverter)

A metal flashing detail installed at the eave end of a roof-to-wall transition designed to direct runoff away from the wall or wall cladding.

Metal flashing

See "flashing"; frequently used as through-wall-, step-, cap- or counterflashing.


The ability of a material to be applied around a penetration or at a roof transition without the need for other flashing materials.

Step flashing

Individual pieces of sheet-metal material used to flash walls, around chimneys, dormers and such projections along the slope of a roof. Individual pieces are overlapped and stepped up the vertical surface.

Strip flashing

Membrane flashing strips used for sealing or flashing metal flashing flanges into the roof or waterproofing membrane.

Through-wall flashing

A water-resistant membrane or material assembly extending completely through a wall and its cavities positioned to direct water within the wall to the exterior, usually through weep holes.