Roofing Glossary: E to H

E

Eave

the lower edge of a sloping roof that part of a roof which projects beyond the wall.

Edge Stripping

Application of felt strips cut to narrower widths than the normal felt roll width to cover a joint between flashing and built-up roofing.

Edge Venting

The practice of providing regularly spaced protected openings at a roof perimeter to relieve water vapor pressure in the insulation. (It is of doubtful efficacy.)

Elastomer

A macromolecular material that returns rapidly to its approximate initial dimensions and shape after subsequent release of stress.

Elastomeric Coating

a coating that is capable of being stretched at least twice its original length (100 percent elongation) and recovering to its original dimensions.

Embedment

the process of pressing a felt, aggregate, fabric, mat, or panel uniformly and completely into hot bitumen or adhesive to ensure intimate contact at all points;
the process of pressing granules into coating in the manufacture of factory prepared roofing, such as shingles.

Emulsion

A mixture of bitumen and water, with uniform dispersion of the bitumen or water globules, usually stabilized by an emulsifying agent or system.

Endlap

The overlap where one panel or felt nests on top of the end of the underlying panel or felt.

Envelope

a continuous felt fold formed by wrapping and securing a portion of a base felt back up and over the felt plies above it. The envelope is intended to prevent bitumen seepage from the edge of the membrane.

EPDM

A synthetic elastomer based on ethylene, propylene, and a small amount of a non-conjugated diene to provide sites for vulcanization. EPDM features excellent heat, ozone and weathering resistance, and low temperature flexibility.

Expansion Joint

A structural separation between two building elements that allows free movement (expansion or contraction) between elements without damage to the roofing or waterproofing system.

Exposure

the traverse dimension of a roofing element or component not overlapped by an adjacent element or component in a roof covering. For example, the exposure of any ply in a built-up roof membrane may be computed by dividing the felt width, minus 2 inches (51 mm), by the number of shingled plies; thus, the exposure of 36 inch (914 mm) wide felt in a shingled, four-ply membrane should be approximately 81/2 inches (216 mm);
the dimension of sidewall or roofing covering that is not covered or overlapped by the up slope course of component. The typical exposure for a standard-sized, three-tab shingle is 5 inches (127 mm), depending on manufacturer specifications.

Extruder

A machine with a driven screw that forces ductile or semi-soft solids through a die opening of appropriate shape to produce continuous film, strip, or tubing.

F

Fabric

a woven cloth of organic or inorganic filaments, threads, or yarns.

Fallback

Reduction in bitumen softening point, sometimes caused by refluxing or overheating in a relatively closed container.

Fascia

in steep-slope roofing, a board that is nailed to the ends of a roof rafter; sometimes supports a gutter;
in low-slope roofing, the vertical or steeply sloped roof or trim located at the perimeter of a building. Typically, it is a border for the low-slope roof system.

Felt

A fabric manufactured from vegetable fibers (organic felts), asbestos fibers (asbestos felts), or glass fibers (glass fiber felts). The manufacturing process involves mechanically interlocking the fibers of the particular felt material in the presence of moisture and heat.

Fishmouth

A half cylindrical or half conical opening formed by an edge wrinkle or failure to embed a roofing felt;
In shingles, a half conical opening formed at a cut edge.

Flange

the projecting edge of a rigid or semi-rigid component, such as a metal edge flashing flange.

Flashings

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

Fleece

Term used to describe mats or felts of usually non-woven fibers.

Flood Coat

the surfacing layer of bitumen into which surfacing aggregate is embedded on an aggregate surfaced built-up roof.

Framed Opening

Frame work (headers and jambs) and flashing which surround an opening in the wall or roof of a building; usually for field-installed accessories such as overhead doors or powered roof exhausters.

G

Gable

the vertical triangular portion of the end of a building having a double-sloping roof, from the level of the eaves to the ridge of the roof.

Galvalume

Trade name for steel coated with aluminum-zinc alloy for corrosion protection.

Galvanized Steel

Steel coated with zinc for corrosion resistance.

Gambrel

a roof that has two pitches on each side, where the upper roof area has fewer slopes than the lower roof areas.

Glass Felt

glass fibers bonded into a sheet with resin and suitable for impregnation with asphalt in the manufacture of bituminous waterproofing, roofing membranes and shingles.

Glaze Coat

The top layer of asphalt in a smooth surfaced built-up roof assembly;
A thin protective coating of bitumen applied to the lower plies or top ply of a built-up membrane, when application of additional felts, or the flood coat and aggregate surfacing are delayed.

Granules

(also referred to as mineral or ceramic granule) opaque, natural or synthetically colored aggregate commonly used to surface cap sheets, shingles, and other granule-surfaced roof coverings.

Gravel

coarse granular aggregate resulting from the natural erosion of rock.

Gravel stop

Flanged device, usually metallic, designed to prevent loose aggregate from washing off the roof and to provide a continuous finished edge for the roofing.

Green Building Technology

Utilizing technology to reduce impact on the earth. Includes recyclability, reduction in carbon dioxide, ozone or other atmospheric pollutants, and reduction of urban heat islands.

Grout

Mixture of cement, sand, and water used to fill cracks and cavities. Often used under base plates or leveling plates to obtain uniform bearing surfaces.

Guarantee

usually refers to the assurance given by the roofing contractor that the work performed by him is in accordance with specification and is without defects.

Gutter

a channeled component installed along the down slope perimeter of a roof to convey runoff water from the roof to the drain leaders or downspouts.

H

Haunch

The deepened portion of a column or rafter, designed to accommodate the higher bending moments at such points. (Usually occurs at connection of column and rafter.)

Head Lap

the distance of overlap measured from the uppermost ply or course to the point where it laps over the undermost ply or course.

Hip

the inclined external angle formed by the intersection of two sloping roof planes.

Hip Roof

A roof which rises by inclined planes from all four sides on the building.

Hood

Cover, usually light gage metal, over piping or other rooftop equipment.

Hot-dip Metallic Coating

Adherent protective coating applied by immersing steel in a molten bath of coating material.

"Hot Stuff" or "hot"

A roofer’s term for hot bitumen.