Term Description
Substrate

The surface upon which a roofing or waterproofing membrane is applied (e.g., in roofing, the structural deck or rigid board insulation).
Sump

An intentional depression around a roof drain or scupper that promotes drainage.
Sump pan

A metal pan used to create a depression around a drain or scupper to enhance drainage.
Surface texture

The resulting surface from the final pass of spray polyurethane foam (SPF). The following terms are used to describe the different SPF surface textures: smooth orange peel, coarse orange peel, verge of popcorn, popcorn, treebark and oversprayed.
Surfacing

(1) The top layer or layers of a roof covering specified or designed to protect the underlying roofing from direct exposure to the weather; (2) the wearing or top layer of a traffic-bearing waterproofing membrane.
Synthetic rubber

Any of several elastic substances resembling natural rubber, prepared by the polymerization of butadiene, isoprene and other unsaturated hydrocarbons. Synthetic rubber is widely used in the fabrication of single-ply roofing membranes.
T-joint

The condition created by the overlapping intersection of three or four sheets in the membrane.
Tab

A section of the exposed portion of a strip shingle defined by cutouts.
Tack-free time

In spray polyurethane foam roofing, a curing phase of polyurethane foam when the material is no longer sticky. When the polyurethane foam is tack-free, it can be sprayed over with another pass, referred to as a "lift." With some care, the polyurethane foam can be walked on soon after it is tack-free. See "lift."
Talc

Whitish powder applied at the factory to the surface of some roofing materials (e.g., vulcanized EPDM membranes), used as a release agent to prevent adhesion of the membrane to itself. Talc is a naturally occurring mineral.
Tapered insulation

A system of precut or premolded insulation boards or a poured insulation fill designed to provide slope to the roof deck before installing the roof membrane.
Taping

(1) The technique of connecting joints between insulation boards or deck panels with tape; (2) the technique of using self-adhering tape-like materials to seam or splice single-ply membranes.
Tar

A brown or black bituminous material, liquid or semisolid in consistency, in which the predominating constituents are bitumens obtained as condensates in the processing of coal, petroleum, oil-shale, wood or other organic materials.
Tear resistance

The load required to tear a material when the stress is concentrated on a small area of the material by the introduction of a prescribed flaw or notch.
Tear strength

The maximum force required to tear a specimen.
Tensile strength

The strength of a material under tension as distinct from torsion, compression or shear.

Termination

The treatment or method of anchoring and/or sealing the free edges of a membrane in a roof or waterproofing system.
Terne

Historically, an alloy of lead and tin used to coat sheets of carbon steel or stainless steel for use as metal roofing sheet; this product is no longer manufactured. "Terne metal," in current use, designates a carbon steel-based metal coated on both sides with a thin layer of zinc and tin alloy.
Test cut

See "core cut."
Test method

A definitive procedure for the identification, measurement and evaluation of one or more qualities, characteristics or properties of a material, product, system or service that produces a test result.
Textural slate roof system

A term used to designate a slate roof system with a range of slate thicknesses mixed throughout; usually uses slates with rougher texture than standard slate with uneven tails or butts.
Thermal barrier

In torched membrane applications over combustible substrates, an above-deck barrier incorporated into a roof system before torching as a fire-safety practice. Acceptable thermal barriers include: minimum 3/4-inch-thick perlite board insulation, minimum 3/4-inch-thick fiberglass or mineral wool board insulation or minimum 1/4-inch-thick glass-faced gypsum board.
Thermal bridge

The penetration of a material of high thermal conductivity (e.g., a metal insulation or roof membrane fastener) through a material of low thermal conductivity (e.g., thermal insulation); the result is a lowered thermal resistance for the assembly.
Thermal conductance (C)

The time rate of steady-state heat flow through a unit area of a material or construction induced by a unit temperature difference between the body surfaces. In English (inch•pound) units of measurement, the number of British thermal units (Btu) that pass through a specified thickness of a 1-square-foot sample of material in one hour with a temperature difference between the two surfaces of 1 degree Fahrenheit. In English (inch•pound) units, it is expressed as Btu/h•ft2•F.
Note 1: A thermal conductance (C) value applies to a specific thickness of a specific material.

Note 2: It is mathematically incorrect to multiply or divide the thermal conductance (C) value for a specific thickness of a material to determine the thermal conductance value of a different thickness of the same material.

Note 3: It is mathematically incorrect to add thermal conductance (C) values to determine overall thermal performance. If it is necessary to determine the overall thermal performance of a construction, it is appropriate to convert the individual thermal conductance (C) values to thermal resistance (R) values (i.e., R = 1/C) and then add the thermal resistance values (i.e., Rt = R1 + R2 + ...).
Thermal conductivity (k)

The time rate of steady-state heat flow through a unit area of a homogeneous material induced by a unit temperature gradient in a direction perpendicular to that unit area. In English (inch•pound) units of measurement, it is the number of British thermal units (Btu) that pass through a 1-inch thickness of a 1-square-foot sample of material in one hour with a temperature difference between the two surfaces of 1 degree Fahrenheit. In English (inch•pound) units, it is expressed as Btu•inch/h•ft2•F.
Note 1: A thermal conductivity (k) value applies to 1-inch thickness of a specific material.

Note 2: It is mathematically incorrect to add, multiply or divide the thermal conductivity (k) value of a material to determine the thermal performance value of a different thickness of the same material. If it is necessary to determine the thermal performance of a specific thickness of a material, it is appropriate to convert the thermal conductivity (k) of the material to a thermal resistance (R) value (i.e., R = 1/k) and then perform the mathematical calculation.

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