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References |
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Glossary
ACCELERATED WEATHERING The process in which
materials are exposed to a controlled environment where
various phenomena, such as heat, water, condensation and
light are altered to magnify their effects, thereby accelerating
the weathering process. The physical properties that result
from this exposure are then measured and compared to those
of the original, unexposed material.
ADHESIVE A substance which joins two or more materials
through chemical bonding.
AGGREGATE (1) Crushed stone, crushed slag, or water-worn
gravel used for surfacing a roof; (2) Any granular mineral
material. (Also BALLAST.)
ALLIGATORING The cracking of the surfacing asphalt on a
built-up roof, producing a pattern of cracks similar to an
alligator’s hide.
ANCHOR BAR A metal strip used to secure a membrane to a
substrate. (Also BATTEN, TERM BAR, TERMINATION BAR.)
APPLICATION RATE The quantity (mass, volume or
thickness) of material applied per unit area.
AREA DIVIDER See Control Joint.
ASBESTOS A group of natural, fibrous impure silicate
materials.
ASPHALT A dark brown or black substance found in a natural
state or, more commonly, left as a residue after evaporating or
otherwise processing crude oil or petroleum. Asphalt is then
further processed to conform to various roofing grade
specifications. (Also BITUMEN.)
ASPHALT, AIR BLOWN An asphalt produced by blowing air
through molten asphalt at an elevated temperature to raise its
softening point and modify other properties.
ASPHALT FELT An asphalt coated or saturated felt.
ASTM American Society for Testing and Materials.
BACKMOP To mop hot asphalt on the back of a roofing
material before embedding it in a mopping of asphalt on the
substrate.
BACK-NAILING The practice of blind-nailing roofing felts to a
substrate in addition to hot mopping to prevent slippage. (Also
BLIND NAILING.)
BACK WATER LAP A lap installed so that water flows against
it.
BALLAST An anchoring material, such as rounded river
rock,gravel, or pre-cast concrete pavers, which is used to hold
single ply roofing membranes in place and to stabilize the roof
system from wind uplift forces. (Also AGGREGATE.)
BASE PLY The bottom or first ply in a roofing membrane when
additional plies are to be subsequently installed.
BASE SHEET A product specifically intended to be used as a
base or first ply in a roofing system.
BATTEN A narrow metal band or plate, usually of galvanized
steel or aluminum, which is used to fasten or hold in place a
single ply membrane.
BIRD BATH A shallow, insignificant amount of water left on the
surface of a roof membrane after a rain.
BITUMEN A generic term for various amorphous, semi-solid
mixtures of hydrocarbons derived from coal or petroleum.
(Also ASPHALT, COAL TAR.)
BITUMEN TRAP See PITCH POCKET.
BLIND NAILING The use of nails that are not exposed to the
weather in the finished roofing. (Also BACK NAILING.)
BLISTER An enclosed pocket of air, which may be mixed with
water or solvent vapor, trapped between impermeable layers of
felt or membrane, or between the membrane and substrate.
BLOCKING (1) Wood built into a roofing system above the
deck and below the membrane and flashing to (a) stiffen the
deck around an opening, (b) act as a stop for insulation, (c)
serve as a nailing subsrate for attachment of the membrane or
flashing; (2) Wood cross-members installed between rafters or
joists to provide support at cross-joints between deck panels;
(3) Adhesion between similar or dissimilar materials in roll or
sheet form that may interfere with the satisfactory and efficient
use of the material.
BLOWING AGENT An expanding agent used to produce a
gas by chemical or thermal action, or both, in manufacture of
hollow or cellular materials including closed cell thermal
insulations.
BLUEBERRY See STRAWBERRY.
BOND The adhesive and cohesive forces holding two roofing
components in intimate contact.
BONNET A conical or pyramid-shaped metal counterflashing
installed on a pipe or other penetration to counterflash a pitch
pocket. (Also UMBRELLA, COOLIE CAP.)
BROOMING Embedding a ply by using a broom or other
device to smooth it out and ensure contact with the adhesive
under the ply.
BUILT-UP ROOFING (BUR) A continuous, semi-flexible
membrane consisting of plies of saturated felts, coated felts,
fabrics or mats assembled in place with alternate layers of
asphalt, and surfaced with mineral aggregate, bituminous
materials, a granule surfaced sheet or some type of liquid
coating.
BULL A slang term for asphalt roofing cement.
