(1) The horizontal, lower edge of a sloped roof; (2) A projecting edge of a roof that extends beyond the supporting wall

The vertical dimension from finished grade to the eave.

Polyepichlorohydrin, commonly referred to as epichlorohydrin.

Felt strips that are cut to widths narrower than the standard width of the full felt roll. They are used to start the felt-shingling pattern at a roof edge.

(1) Application of felt strips cut to narrower widths than the normal width of the full roll to cover a joint between flashing and built up roofing; (2) Membrane flashing strips cut to specific widths used to seal/flash perimeter edge metal and the roof membrane.

(1) The practice of providing regularly spaced protected openings along a roof perimeter to relieve moisture vapor pressure; (2) The practice of providing regularly spaced or continuously protected (e.g., louvered) openings along a roof edge or perimeter, used as part of a ventilation system to dissipate heat and moisture vapor.

(1) A growth of salt crystals on a surface due to evaporation of salt laden water. The deposits that result from this process; (2) The formulation of crystalline deposits, generally whitish in color, on the surface of the stone, brick, concrete or other masonry surface when moisture moves through and evaporates on the masonry. May also be caused by free alkalies leached from mortar, grout or adjacent concrete..

Ethylene Inter Polymer

The property of matter by virtue of which it tends to return to its original size and shape after removal of a stress or force which caused a deformation.

(1) A macromolecular material that returns rapidly to its approximate initial dimensions and shape after substantial deformation by a weak stress and the subsequent release of that stress; (2) Natural or synthetic material which, at room temperature, can be stretched under low stress and, upon immediate release of the stress or force, will return quickly to its approximate original dimensions.

(1) The term used to describe the elastic rubber-like properties of a material; (2) A rubber like synthetic polymer that will stretch when pulled and will return quickly to its original shape when released; (3) Having elastic properties, capable of expanding or contracting with the surfaces to which the material is applied without rupturing; (4) The elastic, rubber-like properties of a material that will stretch when pulled and will return relatively quickly to its original shape when released.

A trade description used to identify elastomeric and plastomeric types of single-ply roof membranes.

A liquid, most often a solution, that will conduct current.

The ability of a material (e.g., roofing membrane) to be stretched by the application of a force.

(1) The process of pressing a felt, aggregate, fabric, mat, or panel uniformly and completely into hot bitumen or adhesive; (2) The process of installing or pressing in a reinforcement felt, fabric, mat or panel uniformly into bitumen or adhesive; (3) The process of pressing granules into coating during the manufacture of factory prepared roofing; (4) The process of placing a material into another material so that it becomes an integral part of the whole material; (5) The process where ply sheet, aggregate or other roofing components settle into hot or cold-applied bitumen via the force of gravity.

The loss of flexibility or elasticity of a material. The transition of a flexible material to a brittle state.

(1) A dispersion of fine particles or globules in a liquid; (2) The intimate dispersion of an organic material and water achieved by using a chemical or clay emulsifying agent; (3) Intimate mixture of bitumen and water, with uniform dispersion of the bitumen globules achieved through a chemical or clay emulsifying agent.

The distance of overlap where one ply, panel or piece extends beyond the end of the immediately adjacent underlying ply, panel or piece.

(1) A continuous membrane edge formed at the perimeter and at penetrations by folding the base sheet or ply over the plies above and securing it to the top of the membrane. The envelope prevents bitumen seepage from the edge of the membrane; (2) A continuous felt fold formed by wrapping and securing a portion of a base felt back up and over the felt plies above it. Envelopes help prevent the seepage of bitumen; (3) Continuous edge formed by folding an edge base felt over the plies above and securing it to the top felt. The envelope thus prevents bitumen seepage through the exposed edge joints of the laminated, built up roofing membrane; (4) Bitumen Stop: A continuous edge seal formed at the perimeter and at penetrations by extending the base sheet or one ply of felt beyond the edge of the membrane field plies. After all overlying field plies or insulation are in place, extended ply is turned back onto the membrane and adhered. The envelope is intended to prevent bitumen seepage from the edge of the membrane. See BITUMEN TRAP.

Environmental Protection Agency

Ethylene Propylene Diene Monomer. See ETHYLENE PROPYLENE DIENE TERPOLYMER.

A synthetic rubber including two epichlorohydrin based elastomers. It is similar to and compatible with EPDM. ECH is typically used in lieu of EPDM when enhanced resistance to animal fat is needed.

A class of synthetic, thermosetting resins that product tough, hard, chemical-resistant coatings and adhesives.

Expanded polystyrene

(1) The moisture content of a material stabilized at a given temperature and relative humidity, expressed as percent moisture by weight; (2) The typical moisture content of a material in any given geographical area.

(1) The temperature at which the viscosity is 75 centipoise for asphalt and 25 centipoise for coal-tar products; the recommended temperature ? 25? F at the time of application; (2) Temperature at which asphalt has the correct viscosity (50 150 cSt) for hot mopping.

(1) A material synthesized from ethylene, propylene and small amounts of diene monomer. It is similar to butyl rubber; (2) Thermosetting, synthetic rubber used in single-ply elastomer sheet roof membranes.

See ETHYLENE PROPYLENE DIENE MONOMER.

(1) The moisture content of a material stabilized at a given temperature and relative humidity, expressed as percent moisture by weight; (2) The typical moisture content of a material in any given geographical area.

The temperature at which a bitumen attains the proper viscosity for built-up membrane application.

The recommended bitumen application temperature range. The range is approximately 25? F (14? C) above or below the EVT, thus giving a range of approximately 50? F (28? C). The EVT Range Temperature is measured in the mop cart or mechanical spreader just prior to application of the bitumen to the substrate.

The recommended EVT for roofing asphalt (ASTM D 312,
Type I, II, III or IV) is as follows:

Mop Application: The temperature at which the asphalt's apparent viscosity is 125 centipoise (0.125 Pa s).

Mechanical Spreader Application: The temperature at which the asphalt's apparent viscosity is 75 centipoise (0.75 Pa s).

Note: If there are simultaneous mop and mechanical spreader applications, in order to avoid the use of two kettles, the EVT for mechanical spreader application may be used for both application techniques.

The recommended EVT for roofing coal-tar (ASTM D 450, Type I or III) is the temperature at which the coal tar's apparent viscosity is 25 centipoise (0.025 Pa s).

A group of thermoplastic compounds generally based on PVC polymers from which certain single-ply roofing membranes can be formulated.

Designated nomenclature of ASTM for a terpolymer of ethylene, propylene and a diene. EPDM material is a thermosetting synthetic elastomer.

Equiviscous Temperature

Equiviscous Temperature

Air that is typically vented or exhausted from the roof cavity, typically through vents installed on the upslope portion of the roof. For example, with most steep-slope roof assemblies exhaust vents are typically located at or near the ridge.

(Manville)

(1) A structural separation between two building elements that allows free movement between the elements without damage to the roofing or waterproofing system; (2) A structural separation between two building elements designed to minimize the effect of the stresses and movements of a building's components and to prevent these stresses from splitting or ridging the roof membrane. (See NRCA Construction Detail C-1).

(1) The transverse dimension of a roofing element not overlapped by an adjacent element in any roof system. The exposure of any ply in a membrane may be computed by dividing the felt width minus 2" by the number of shingled plies; thus, the exposure of 36" wide felt in a shingled, four-ply membrane should be 8-1/2"; (2) The time during which a portion of a roofing element is exposed to the weather; (3) Transverse dimension of a felt not overlapped by an adjacent felt in a built-up roof membrane. Correct felt exposure in a shingled, built-up membrane is computed by dividing the felt width minus 2" by the number of plies--e.g., for four plies of 36"-wide felt, exposure = (36-2)/4 = 8 1/2"; (4) That portion of the roofing exposed to the weather after installation. See PLY.

(1) The process of extruding or forcing a material (under heat and pressure) through a die of specified shape. Plastic and aluminum materials may be extruded into various shapes by this process; (2) A manufacturing process which consists of forcing batched and formulated material (which may be molten) through an orifice called a "die". The shape and dimensions of the orifice determine the shape and dimensions of the finished product. Extrusion is one method by which some single-ply roofing membranes are manufactured.