Window Glossary
There are currently 7 names in this directory beginning with the letter R.
R-value:Resistance to thermal transfer or heat flow. Higher R-value numbers indicate greater insulating value. R-value is reciprocal of U-factor (or rate of heat flow).
Rail:Horizontal member of the framework of a window sash or door.
Replacement Window:Any window custom made to replace an older window.
Retro-Fit Window Installation (insert window)A method of installing a replacement window inside the frame of an older wood window.
Roof Window:An operable unit similar to a skylight placed in the sloping surface of a roof.
Rough Opening (RSO):Opening in a wall into which a window or door is installed. In wood frame construction this opening is often called the RSO (rough stud opening).
Round-top:One of several terms used for a variety of window units with one or more curved frame members, often used over another window or door opening.
