Parallel Circuit: Each element is individually connected across the energy source instead of all of the elements being connected to each other and then the battery source; also known as multiple connection circuit.
Parapet Wall: The part of a perimeter wall that extends above the roof. Pascal: The unit of measure for force per unit area; 1 Pa=1 N/m2.
Percussion Sounding: The process of sharply striking the vessel sides with a non-marring hammer or instrument and listening to the sound to assist in identifying voids, delamination, debonds, or core degradation.
Period: The amount of time required for one cycle. The period can be determined by dividing the frequency into T = 1/F.
Passive Thermography: The act of inspecting target without using external heat source. Pest: An animal, critter, insect, or organism whose presence is unwanted.
Pest-related damage: The resulting destruction of property or structure or the construction of unwanted nests or structures by pests.
Polychlorinated Biphenyl (PCB): A chemical used in askarels, which has been banned by the EPA due to its cancer-causing characteristics.
Polyvinyl Chloride Membrane (PVC): A single ply roof membrane produced by a chemical reaction known as polymerization.
Photovoltaic (PV): A method of generating electrical power by converting solar radiation into direct current electricity using semiconductors.
Plastic Cement: A roofing industry generic term used to describe asphalt roof cement that is a trowelable mixture of solvent-based bitumen, mineral stabilizers, and other fibers and/or filters. Generally, intended for use on relatively low slopes, not vertical surfaces. (See Asphalt Roof Cement and Flashing Cement.)
Polymer Modified Bitumen: See Modified Bitumen.
Pond: A surface that does not drain completely.
Ponding: The excessive accumulation of water at low-lying areas on a roof that remains beyond the 48- hour drying window. This period starts at the end of rainfall when conditions are conducive to drying.
Positive Pertinent Finding: An exception that is indicative of a problem, such as a void or liquid intrusion, and has been confirmed by destructive or visual testing.
Post Processing: The technique whereby captured thermal images are later analyzed using computer software. Typical analysis techniques include adjusting for emissivity, atmospheric temperature and relative humidity, and color palette selection.
Power: Rate of doing work in foot-pounds/second. The unit of measure of electrical power is the watt. Power Factor: The ratio of true power to apparent power. Power factor is equal to the Cos9.
Primary Winding: The coil of a transformer that is connected to the power source.
Protected Membrane Roof (PMR): An insulated and ballasted roofing assembly in which the insulation and ballast are applied on top of the membrane. The system is sometimes referred to as an “inverted roof assembly”.
Pyranometer: An electronic device used to measure broadband solar irradiance on a planar surface from a field of view of 180°.
