pressure regulator: a device that is used to reduce the pressure of a fluid to a desired level. In the home, the most common example is the regulator on the natural gas meter.

pressure tank: a reservoir tank that holds water under pressure, allowing water to flow through the pipes without the well pump turning on every time a faucet is opened, prolonging the lifespan of the pump. The pump will turn on to replenish the water in the pressure tank if the level drops below a set amount.

PSI: acronym for Pounds per Square Inch. It is the method used to describe the amount of force (pounds) exerted across an area (square inch). In the home, it is used to describe the amount of pressure in the potable water system.

PVC: polyvinyl chloride. A synthetic material made when vinyl chloride is polymerized. PVC is a type of plastic, and is used in various materials in the home, such as plumbing pipes, molding, trim, roofing, flashing, doors, windows and many other items.

rafter: one of the parallel structural members designed to support the roof of the house.

reducer: a fitting that is used to join together pipes or ducts of different sizes.

A structure designed to hold back lateral pressure of soil. A retaining wall enable a change of level in the soil that would not naturally exist.

In an HVAC system, the area through which building air is pulled into the heating/cooling system. The HVAC filter is typically located at the beginning (or end) of the return air shaft.

ridge board: the horizontal board at the top of the attic, that the rafters are nailed to.

ridge vent: a static vent, located at the highest point of an area of the roof (the ridge), which allows for the ventilation of warm air from the attic area.