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References |
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Glossary
PEEL STRENGTH The average force (or force per unit width)
required to peel a membrane from the substrate to which it has
been bonded.
PERLITE BOARD An insulation board containing perlite, a
volcanic ore which when heated, expands and becomes a
good insulator.
PHASED CONSTRUCTION The installation of a roofing or
waterproofing system during two or more separate time
intervals; a roofing system not installed in a continuous
operation. Also known as PHASE APPLICATION, PHASING.
PIB Abbreviation for "polyisobutylene."
PIPE BOOT Prefabricated flashing used to flash around
circular pipe penetrations.
PICTURE FRAMING (1) A rectangular pattern of ridges in a
membrane over insulation or deck joints. (2) A method of
providing additional attachment around the perimeter of a
building, usually on SPM mechanically attached systems.
PINHOLE A tiny hole in a film, foil, or laminate comparable in
size to one made by a pin.
PITCH POCKET An enclosure made of sheet metal, rubber,
or other material, used to flash penetrations through a roof
system. Also known as pitch pan and PENETRATION PAN.
PLASTIC CEMENT A generic term used to describe a utility
asphalt roof cement intended for use on low slopes.
PLASTICIZER A chemical substance (e.g., an organic
compound) added to natural or synthetic resins for the purpose
of increasing flexibility, and facilitating processing and
workability.
PLY A layer of felt in a bituminous roofing membrane; a four-ply
membrane has at least four plies of felt at any vertical cross
section cut through the membrane.
POLYISOCYANURATE INSULATION A rigid foam roof
insulation board produced from polyisocyanurate based
chemicals. Also commonly referred to as isocyanurate or "iso".
PONDING The surface accumulation of water in low-lying or
poorly drained areas of a roof. If ponding is excessive, the
weight may result in a load which exceeds the design capacity
of the structure, or possibly cause premature deterioration of
the membrane.
POURABLE SEALER A specific type of sealant used at
difficult-to-flash penetrations, typically in conjunction with "pitch
pockets" to form a weathertight seal.
PRIMER A thin liquid applied to a surface to improve the
adhesion of heavier applications of hot or cold adhesives and
to absorb dust.
PROTECTED ROOFING MEMBRANE ASSEMBLY (PRMA)
An insulated, and ballasted roofing assembly, in which the
insulation and ballast are applied on top of the membrane.
Sometimes called an "inverted assembly" or an "upside down
roof."
PVC Abbreviation for "polyvinyl chloride."
RACKING To stretch or strain by force. Also diagonal wrinkles
in flashing materials which indicate differential movement
between deck and wall.
RAG FELT Now, a generic term referring to an organic felt.
Formerly, a roofing felt composed of mainly cotton rag fibers.
RAGGEL 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.
RASPBERRY See STRAWBERRY.
REGLET A groove in a wall or other surface adjoining a roof
surface for the attachment of counterflashing.
RELEASE AGENT See PARTING AGENT.
REROOFING The process of recovering or replacing an
existing roofing system.
RESISTANCE, THERMAL The measurement of the
resistance to heat flow.
RIDGING An upward, tenting displacement of a membrane,
frequently over an insulation joint.
RIEI Abbreviation for "Roofing Industry Educational Institute," a
non-profit educational institute dedicated to increasing and
disseminating knowledge about roofing technology.
ROLL ROOFING Coated felts, either smooth or
mineral-surfaced.
ROOF CEMENT See FLASHING CEMENT, PLASTIC
CEMENT.
ROOF VENT A vertical outlet in a built-up roofing system to
relieve the pressure exerted by water vapor between the
roofing membrane and the vapor retarder or deck.
ROOFING SYSTEM An assembly of interacting components
designed to weatherproof, and normally to insulate, a
building’s top surface.
