01 May 1999
Polyols--A polyhydric alcohol, i.e.,
by the application of heat.
containing three or more hydroxyl groups.
Ply--A layer of felt in a roofing membrane; a
four-ply membrane should have at least four
thermoplastic polymer, with a molecular weight
plies of felt at any vertical cross section cut
of 40,000 or more.
through the membrane.
Ply (Plywood)--A single veneer lamina in a
glued plywood panel.
vinylchloride. PVC can be compounded into
flexible and rigid forms through the use of
Plywood--A flat panel built up of sheets of wood
plasticizers, stabilizers, filler, and other
veneer called plies, united under pressure by a
modifiers; rigid forms used in pipes; flexible
bonding agent to create a panel with an
forms used in manufacture of sheeting.
adhesive bond between plies as strong as or
stronger than, the wood. Plywood is constructed
of an odd number of layers with grain of
Pond--A roof area that retains water instead of
adjacent layers perpendicular. Layers may
draining after rainfall.
consist of a single ply or two or more plies
laminated with parallel grain direction. Outer
Ponding--Water in low or irregular roof areas
layers and all odd numbered layers generally
that remains longer than 48 hours after the
have the grain direction oriented parallel to the
cessation of rainfall.
long dimension of the panel.
Pot Life--The working time once a product has
Pointing--(1) Troweling mortar into a joint after
been reacted (catalyzed).
masonry units are laid. (2) Final treatment of
joints in cut stonework. Mortar or a putty-like
Pre-painted coil--Coil steel which receives a
filler is forced into the joint after the stone is set.
paint coating prior to the forming operation.
Press brake--A machine used in cold-forming
manufactured fiber in which the fiber-forming
metal sheet or strip into desired cross-section.
substance is any long chain synthetic polymer
composed of an ester of a dihydric alcohol and
Prestressed concrete--Concrete in which the
terephthalic acid. Scrims made of polyester fiber
reinforcing cables, wires, or rods in the concrete
are used for fabric reinforcement.
are tensioned before there is load on the
member, holding the concrete in compression
Polyisobutylene--The polymerization product of
for greater strength.
isobutylene varying in consistency from a
viscous liquid to a rubberlike solid, with
corresponding variation in molecular weight from
scheduled, inspection for and the repair of
1,000 to 400,000.
normal, expected breakdown of materials and
Polyisocyanurate--Thermoset polymer formed
by polymerization of isocyanate; rigid foam
Prime coat--First liquid coat applied in a
insulation meeting ASTM C1289; a thermal
multiple coat system.
insulation similar in appearance to polyurethane
foam, but with improved fine resistance or rating.
Primer (bituminous)--A thin liquid bitumen
applied to a surface to improve the adhesion of
Polymer--A macromolecular material formed by
heavier applications of bitumen and to absorb
the chemical combination of monomers having
either the same or different chemical
are all high molecular weight polymers.
assembly with insulation on top of membrane
instead of vice versa, as in conventional roof
assembly (also known as inverted or upside-