R-Value: the resistance to heat transfer of a material. Insulators have relatively high R values.

 

Rafter: one of a series of sloped structural members, that extend from the ridge or hip to the downslope perimeter or eave, designed to support the roof deck and its associated loads.

 

Raggle: a groove or slot, often cut in a masonry wall or other vertical surface adjoining a roof, for inserting an inset flashing component such as a reglet.

 

Rake: the sloped edge of a roof at or adjacent to the first or last rafter.

 

Rake-Starter (Bleeder Strip): starter-strip used along rake edges in conjunction with asphalt shingle roofing.

 

Re-Cover: the addition of a new roof membrane or steep-slope roof covering over a major portion of an existing roof assembly. This process does not involve removal of the existing roofing.

 

Reglet: a sheet metal receiver for the attachment of counterflashing. (A reglet may be inset into a raggle, embedded behind cladding, or be surface mounted.)

 

Reinforced Membrane: a roofing or waterproofing membrane that has been strengthened by the addition or incorporation of one or more reinforcing materials, including woven or nonwoven glass fibers, polyester mats or scrims, nylon, or polyethylene sheeting.

 

Replacement: the practice of removing an existing roof system down to the roof deck and replacing it with a new roofing system.

 

Reroofing: the process of re-covering, or tearing-off and replacing an existing roof system.

 

Ridge: highest point on the roof, represented by a horizontal line where two roof areas intersect, running the length of the area.

 

Ridge Cap: a material or covering applied over the ridge of a roof.

 

Ridge Course: the last or top course of roofing materials, such as tile, roll roofing, shingles, etc., that covers the ridge and overlaps the intersecting field roofing.

 

Ridge Vent: a ventilator located at the ridge that allows the escape of warm and/or moist air from the attic area or rafter cavity. Most ridge vents are either premanufactured metal or flexible, shingle-over type.

 

Ridging: see Buckle.

 

Roll Roofing: smooth-surfaced or mineral-surfaced, coated, prepared felts.

 

Roof Assembly: an assembly of interacting roof components (includes the roof deck, vapor retarder [if present],insulation, and roof covering).

 

Roof or Roofer’s Cement: see Asphalt Roof Cement or Coal Tar Roof Cement.

 

Roof Covering: the exterior roof cover or skin of the roof assembly, consisting of membrane, panels, sheets, shingles, tiles, etc.

 

Roof Curb: raised frame used to mount mechanical units (such as air conditioning or exhaust fans), skylights, etc.

 

Roof Jack: a metal bracket used to support toe-boards on steep-slope roofs.

 

Roof Overhang: a roof extension beyond the exterior wall of a building.

 

Roof Seamer: machine that crimps neighboring metal roof panels together, or that welds laps of membrane sheets together using heat, solvent, or dielectric energy.

 

Roof System: a system of interacting roof components, generally consisting of membrane or primary roof covering and insulation (not including the roof deck) designed to weatherproof and, sometimes, to improve the building’s thermal resistance.

 

Rosin Paper (specifically Rosin-Sized Sheathing Paper): a non-asphaltic paper used as a sheathing paper or slip sheet in some roof systems.

 

Rubber: a polymeric material which, at room temperature, is capable of recovering substantially in shape and size after removal of a force. May be natural or synthetic.

 

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