SPF that has excess isocyanate or resin. Off-ratio will not exhibit the full physical properties of normal SPF.
O
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
A method of valley construction in which the steep-slope roofing on both sides are trimmed along each side of the valley, exposing the metal valley flashing.
Orange Peel Surface Texture
In SPF roofing, a condition of the foam in which the surface shows a fine texture and is compared to the exterior skin of an orange. This surface is considered acceptable for receiving a protective coating.
Organic
Being or composed of hydrocarbons or their derivatives, or matter of plant or animal origin.
Organic Felt
An asphalt roofing base material manufactured from cellulose fibers.
Organic Shingle
An asphalt shingle reinforced with material manufactured from cellulose fibers.
ORNL
Oak Ridge National Laboratory
Overflow Drainage
Component in a roof drainage system used to protect the roof against damage from a water load imposed by blocked or partially blocked primary drainage system; e.g., overflow scupper, overflow interior drain.
Overspray
Undesirable depositions of airborne spray.
Overspray Surface Texture
In SPF roofing, a condition of the foam in which the surface shows a linear coarse textured pattern and/or a pebbled surface. This surface is generally downwind of the sprayed polyurethane path and, if severe, unacceptable for proper coating coverage and protection.
Ozone
A triatomic form of oxygen that is a bluish gas of pungent odor; is formed naturally in the upper atmosphere by a photochemical reaction with solar ultraviolet radiation.
Ozone Resistance
The ability of a material to resist the deteriorating effects of ozone exposure.