A measure of insulation's resistance to heat flow. The higher the r value the more effective the insulation.Ê For example, typical new home's walls are usually insulated with 6" of bat insulation with an r value of r-19, and a ceiling insulation of r-28.
R-value
Measurement of a material's resistance to heat loss, most often referring to insulation products. The higher the R-Value, the slower the rate of loss.
Rabbet
A notch or groove cut into a piece of material to allow two sections to be combined with a flush joint.
Rabbet plane
A woodcutting tool used to cut an L-shaped groove into a piece of material.
Race
Races are the guides in which bearings are held and through which they move.
Raceway
(1) An enclosed metal channel, usually fire-resistant, installed in a building to hold electrical wiring. (2) A chute that directs the flow of a material to a specific location in a device.
Raceway, one piece
A channel holding electrical wiring that is designed to look like a piece of decorative trim or molding.
Raceway, overfloor
A channel holding electrical wiring designed to be installed on a floor. The unit has a low profile and sloping edges to facilitate walking over it.
Racial steering
The illegal practice of directing certain races away from some neighborhoods and into others.
Rack
(1) A storage unit designed to hold various objects. (2) To cause a structure to shift so that it is out of plumb.
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