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."
Liquid-applied roof membrane

A continuous roof membrane constructed in place with a liquid resin and reinforcing material. The liquid resin is available as a one- or two-component product and typically is applied in two coats. Depending on resin chemistry, a catalyst or hardener may be added to induce the curing process. The reinforcement typically is polyester or fiberglass mat set into the resin base coat.
Loose-laid membrane

Ballasted membrane that is attached to the substrate only at the edges and penetrations.
Mechanically fastened membrane

Generally used to describe a membrane that has been attached to the substrate at defined intervals.
Membrane

A flexible or semiflexible roof covering or waterproofing whose primary function is to exclude water.
Protected membrane roof (PMR)

An insulated and ballasted roof assembly in which the insulation and ballast are applied on top of the membrane (sometimes referred to as an inverted roof assembly).
Reinforced membrane

A roof or waterproofing membrane that has been strengthened by the addition or incorporation of one or more reinforcing materials, including woven or nonwoven glass fibers, polyester mats or scrims, nylon or polyethylene sheeting.
Self-adhering membrane

A membrane that can adhere to a substrate and to itself at overlaps without the use of an additional adhesive. The undersurface of a self-adhering membrane is protected by a release paper or film, which prevents the membrane from bonding to itself during shipping and handling.

Single-ply membranes

Roof and waterproofing membranes that are field applied using just one layer of membrane material (either homogeneous or composite) rather than multiple layers.
Thermoplastic olefin membrane (TPO)

A blend of polypropylene and ethylene-propylene polymers, colorant, flame retardants, ultraviolet radiation absorbers and other proprietary substances that may be blended with the TPO to achieve the desired physical properties. The membrane may or may not be reinforced.
Vegetative roof waterproofing membrane

A continuous layer used as a treatment of a surface or structure to prevent the passage of water under hydrostatic conditions; used specifically for a vegetative roof system. (See ‚"waterproofing membrane.‚")

Water and ice-dam protection membrane

A continuous membrane installed under steep-slope roofing materials in areas subject to ice damming or wind-driven rain that prohibits water that gets through the roof covering from getting into the structure; ice- and water-protection membranes classified by ASTM D1970 must also seal around fasteners.
Waterproofing membrane

(1) The part of a waterproofing system that has the primary function of excluding water; it does not include accessories such as drainage materials or protection boards. See "membrane;" (2) a continuous layer used as a treatment of a surface or structure to prevent the passage of water under hydrostatic conditions.