Treatment of a surface or structure to resist the passage of water in the absence of hydrostatic pressure.

(1) The term used to describe an absolutely horizontal roof; (2) Essentially horizontal or flat, as in a roof deck or rooftop with no intentional slope to the roof drains. Also referred to as zero (0) slope. See SLOPE.

A roofing asphalt that has a softening point of 140? F (60? C) and that conforms to the requirements of ASTM Standard D 312, Type I. See ASPHALT.

(1) Non-moving rooftop loads, such as mechanical equipment, air conditioning units and the roof deck itself; (2) Permanent non moving loads that result from the weight of a building's structural and architectural components, mechanical and electrical equipment, and the roof assembly itself. Essentially the same as "dead weight" or "dead weight loads".

(1) The structural surface to which the roofing or waterproofing system (including insulation) is applied; (2) The surface, installed over the supporting framing members, to which the roofing is applied; (3) A structural component of the roof of a building. The deck must be capable of safely supporting the design dead and live loads, including the weight of the roof systems, and the additional live loads required by the governing building codes. Decks are either non-combustible (e.g., corrugated metal, concrete or gypsum) or combustible (e.g., wood plank or plywood), and provide the substrate to which the roofing or waterproofing system is applied.

The downward displacement of a structural member or system under load.

A deleterious change in the chemical structure, physical properties or appearance of a material due to natural or artificial exposure (e.g., exposure to radiation, moisture, heat, freezing, wind, ozone, oxygen, etc.).

The difference between a reference temperature (usually 65? F, 18.3? C) and the mean temperature for the day, times 24 hours, times the number of days in the period. Degree days are used to compare the severity of cold or heat during the heating or cooling season.

(1) Separation of the plies in a built-up roof membrane system or separation of laminated layers of insulation or insulation boards into horizontal strata; (2) Separation of the laminated layers of a component or system.

Separation of the plies in a membrane system or separation of any laminated materials in composite form.

Dens-Deck is engineered to be bendable, but extra tough, so it resists puncturing, handling and potential installation damage. Due to its high compressive strength, Dens-Deck holds up under foot traffic and other impact. And it increases deck stiffness, easily spanning metal deck types B, F and N without the need for added bridging material. Dens-Deck passes FM Hail Damage test.

What's more, Dens-Deck is easy to handle. Its lightweight, scores and snaps easily and cleanly, and comes in 4' x 8' sheets for less handling, faster work, and lower installation costs. Dens Deck is available in 1/4", 1/2" and 5/8" thicknesses. All products achieve 60 and 90 psf FM uplift requirements.

Those loads specified in building codes or standards published by federal, state, county or city agencies or in owner's specifications to be used in the design of a building.

The temperature at which water vapor starts to condense in cooling air at the existing atmospheric pressure and vapor content. Cooling at or below the dew point will cause condensation See CONDENSATION.

See ROOF DIAPHRAGM.

The ability of a material to resist change in length and/or width and/or thickness that results from exposure to elevated or freezing temperatures, and moisture, over time.

Decameter

Decimeter

Department of Energy

A framed window unit projecting through the sloping plane of a roof.

The process of applying two layers or flood coats of bitumen and aggregate to a built-up roof. Loose aggregate should be swept from the first application prior to the second coating of bitumen and aggregate. Approximately 50% of the second aggregate application will remain adhered in the bitumen flood coat unless physically removed.

(1) The process of applying two layers of aggregate and bitumen to a built-up roof; (2) Doubling of the flood coat, graveling-in operation, to provide additional waterproofing integrity to the membrane.

A conduit used to carry runoff water from a scupper, conductor head or gutter of a building to a lower roof level or to the ground or storm water runoff system.

(1) A device that allows for the flow of water from a roof area; (2) An outlet or other device used to collect and direct the flowof runoff water from a roof area (See NRCA Construction Details W 1 and W 2).

(1) A non-corrosive, non-staining material used along the eaves and rakes to allow water run-off to drip clear of underlying construction; (2) A metal flashing or other overhanging component, with an outward projecting lower edge, intended to control the direction of dripping water and help protect underlying building components. A drip edge also can be used to break the continuity of contact between the roof perimeter and wall components to help prevent capillary action.

A reduction in the softening point of bitumen that occurs when bitumen is heated in the absence of air. See SOFTENING POINT DRIFT.

The property of the material to withstand deformation by stretching, without recovery of shape upon removal of the stretching force.

Any load which is nonstatic, such as a wind load or a moving live load.