This glossary contains many useful terms and definitions that will help you understand much of the work we do at ROOFCORP.

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Off-ratio foam: SPF that has excess isocyanate or resin. Off-ratio will not exhibit the full physical properties of normal SPF.

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.

Osmosis: movement of a solvent through a semipermeable membrane into a solution of higher solute concentration that tends to equalize the concentration of solute on the two sides of the membranes.

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.