Hectare

Resistance of the elastomeric membrane to indentation under test conditions which do not cause rupture.

Cinder block wall.

(1) The minimum distance, measured at ninety degrees (90?) to the eaves along the face of a shingle or felt, from the upper edge of the shingle or felt to the nearest exposed surface; (2) Shortest distance from the butt edge of an overlapping shingle to the upper edge of a shingle in the second course below. The triple coverage portion of the top lap of strip of shingles; (3) The distance of overlap measured from the uppermost ply or course to the point that it laps over the undermost ply or course.

(1) The ability of the membrane to retain its physical properties after continued exposure to heating above room temperature. Submitting a material to prolonged exposure at elevated temperatures; (2) Controlled exposure of materials to elevated temperatures over time.

The process of joining thermoplastic films, membranes or sheets by heating and then applying pressure to bring both materials in contact with each other. See HEAT WELDING.

The transmission of thermal energy from a location of higher temperature to a location of lower temperature. This can occur by conduction, convection or radiation.

Method of melting and fusing together the overlapping edges of separate sections of thermoplastic or uncured elastomeric roofing membranes by the application of heat (in the form of hot air or open flame) and pressure. See HEAT SEAMING.

The inclined external angle formed by the intersection of two sloping roof planes. Runs from the ridge to the eaves.

(1) A type of roof containing sloping planes of the same pitch on each of four sides. Contains no gables; (2) A roof that rises by inclined planes from all four sides of a square or rectangular shaped building.

Shingles used to cover the inclined external angle formed by the intersection of two sloping roof planes.

Hektomete

A mechanical lifting device.

(1) An area where a liquid-applied material is missing or absent; (2) An area where interply bitumen mopping or other fluid applied coating is discontinuous.

Sheet metal cover over piping or other rooftop equipment.

See FEATHERING STRIPS.

The roofer's term for hot bitumen.

Horse Power

Hour

The amount of moisture contained in the atmosphere. Generally expressed as percent relative humidity (the ratio of the amount of moisture [water vapor] actually present in the air, compared to the maximum amount that the air could contain at the same temperature.)

Heating, ventilating and air conditioning equipment.

An organic chemical compound primarily containing the elements carbon and hydrogen.

A colorless, fuming, corrosive, dangerously poisonous aqueous solution of hydrogenflouride, HF, used to clean masonry, pickle certain metals, and etch or polish glass.

The term used to describe a material which attracts, absorbs and retains atmospheric moisture.

A registered trademark of E.I. duPont de Nemours, Inc., for "chlorosulfonated polytheylene" (CSPE). Basically a chlorinated polyethylene containing chloro sulphonyl groups with a high molecular weight, low-density polyethylene. See CHLOROSULFONATED POLYETHYLENE, CPE, and CSPE.