Also called meeting rails, they are the top horizontal sash member of the bottom window and the bottom horizontal sash member of the top window in a double hung window that mate together tightly when closed, permitting no air passage between the sashes.
Check valve
A type of backflow preventer installed in a pipe run that allows water to flow in only one direction.
Checking
A pattern of surface cracks running in irregular lines. When found in the top pour of an asphalt built-up roof, is the preliminary stage of alligatoring.
Checks
Splits or cracks in a board, ordinarily caused by seasoning.
Cheek
Either of two sides of an object, such as a door jamb or the jaws of a vise.
Cheek cut
A chamfer cut along the wide part of a board end, allowing the board to fit securely against another framing member at an angle, like at the end of a hip rafter.
Cheek wall
A side of an object.
Cheesecloth
Chemical
Substance used in or obtained by a chemical process.
Chemical energy efficiency
The energy liberated in a chemical reaction, as in the combustion of fuels.
