Nonshingled
application pattern of a single ply of felt
followed later by application of a second
ply. See PHASED APPLICATION.
OPEN TIME
The period
of time after an adhesive has been applied
and allowed to dry, during which an effective
bond can be achieved by joining the two
surfaces.
OPEN VALLEY
Method
of valley construction in which shingles
on both sides of the valley are trimmed
along a chalk line snapped on each side
of the valley. Shingles do not extend across
the valley. Valley flashing is exposed.
ORGANIC
(1) A
material composed of hydrocarbons or their
derivatives; matter of plant or animal origin;
(2) Being or composed of hydrocarbons or
their derivatives originating from plant
or animal matter.
ORGANIC FELT
An asphalt
roofing base material manufactured from
cellulose fibers.
ORNL
Oak Ridge
National Laboratory
OSHA
Occupational
Safety & Health Agency
OSMOSIS
The diffusion
of fluids through a semi-permeable membrane
or porous partition.
OVERHANG
That portion
of the roof structure that extends beyond
the exterior walls of a building.
OVERLAY SHINGLE
A one-piece
base shingles to which overlay pads, consisting
of an additional layer of asphalt and granules,
are applied in random patterns to simulate
two-piece laminated shingles.
OVERSPRAY
To spray
beyond a boundary. That which has been sprayed
beyond a boundary.
oz
Ounce
OZONE RESISTANCE
(1) The
ability of the membrane to resist long-term
exposure to ozone; (2) The ability of a
material to resist the deteriorating effects
of ozone exposure.
