The sliding glass door or sliding panels. While these panels are traditionally interior pieces, the Western sliding glass door is an exterior piece also called a “patio door”, for the patio they usually open onto. These doors are made of glass and allow a great amount of natural daylight in. Once an architectural luxury, the post-war building boom saw them installed in many homes, usually ranch-style houses.
Early sliding glass doors looked great, but they were a source of energy loss and a weak point for security. Modern sliding glass doors look even better, are stronger, and much better insulated.