Definitions of Terms under Alphabet R
Rough Opening

A structurally-framed opening in a wall for a door or window.


A term which describes the part of an adjustable sill which can be moved up or down by turning adjusting screws.


The offset or space between edges of parts.


In stile and rail doors, horizontal pieces at the top and bottom edges at intermediate points, connecting the stiles together.

Rabbet, Rebate

A groove or step cut along the length of the edge of a piece of wood that is to be joined to another with a corresponding tongue or ledge cut into it.


A number which describes in relative terms the ability of a material or assembly to resist the flow or transmittance of heat. Assemblies or materials with high R-values are better insulators than those with lower R-values.