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Window & Door Terms - R

Window & Door Terms - R

R-Value
The resistance to heat flow through a material. The higher the number, the greater the resistance.
Rail
The horizontal top or bottom piece of a door or window frame or sash.
Rim
Rough-in frame work. 2x10s placed along the foundation of a home, which supports or is nailed to the floor joists. The side of the 2x10s measure 1 1/2" and are placed down on the foundation.