Nailer
Lumber and or plywood material (incl osb) secured to the deck, or walls, that provides a receiving medium for the fasteners used to mechanically attach single ply membranes, or flashing. |
Net Free Vent Area
Area open to unrestricted air flow. Commonly used as a measuring unit of sorts, to measure vent performance. (eg; area of the opening of vent, minus the area displaced by the screening material) |
Night Seal / Night Tie In
The method of temporarily sealing an existing membrane edge to the newly installed membrane edge, while roof installation is underway, but halted by nightfall. This method is used to protect structure from possible water until roof installation can resume. |
Non Traffic Bearing
A roof system that will not withstand foot traffic without reinforcement / protection (walk tread etc) |
Nonwoven Fabric
A roofing related textile structure processed by bonding or interlocking fibers. This is accomplished by use of chemicals, thermal, solvent or mechanical processes. |
NRCA
National Roofing Contractors Association |
Open Valley
A type of material installation in the valley (steep slope roofs) where both sides of the valley are trimmed, and metal installed (exposed) in the valley |
Organic
Composed of hydrocarbons or derivatives, or of plant or animal design. |
Overflow Drainage
A component in a roof drainage system. This component is to safeguard the roof structure in the event primary drains are blocked, or partially blocked, thus there is a large collection of water on the roof. (scuppers, overflow interior drains) |
Parapet Wall
The portion of the perimeter wall that extends above the roof level. |
Pass
Refers to one layer of roofing material applied, typically in regards to spray materials. (SPF, emulsion etc) |
Pedestal
A base, or support for roof top components, HVAC units, pipes, pavers etc. |
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Penetration
Any fixture construction that passes through the roof surface (HVAC, pipes, conduits etc) |
Perlite
Aggregate used in insulating concrete and preformed insulation boards |
Pipe Boot
Prefabricated flashing unit used to flash around pipe penetrations. |
Pitch Pan / Pitch Container
Flanged open bottomed fixture made of sheet metal (or other) placed around a roof penetration, filled with sealants to seal the area around penetrations. |
Plasticizer
Material incorporated (mixed) in a material increasing it's ease of flexibility or warkability. |
Pliability
Property of a roofing material to be flexible or moldable. |
Ply
A layer of felt or sheet in a BUR (built up roof) system. |
Polymer
Macromolecular material formed by chemical combination of monomers
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Polyvinyl Chloride / PVC
Synthetic Thermoplastic polymer processed from vinylchloride. The flexibility or rigidity of PVC is contingent upon the use of plasticizers, stabilzers, fillers and other modifiers. EG, used in pipes for plumbing (rigid form) single ply membranes (flexible form) |
Pond (ponding)
On a roof surface, an area that is incompletely drained. |
Primer
Solvent based, liquid applied bitumen, typically used to approve adhesion of bitumen based roofing materials, applied to the substrate. |
PVC
Polyvynil Cloride |
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