Patio doors, part 1: from wood to aluminum and beyond

By definition, a patio door is nothing more than a door that opens onto a patio, but a patio door has commonly come to mean a sliding door that leads outside the home.

The first popular patio doors: wood sliders

The popularity of patio doors is not new, and, in fact, the first ones were heavy wood sliders. They had thick door panels and slid open and shut on primitive rollers along a track. Only half of the door opened, meaning a door with an opening six feet wide provided only three feet of width to pass through.

Wood door frames needed painting on the outside to protect them from the elements. If the panels were glass and the paint was not lapped over onto the glass, water dripping down the door eventually destroyed the glazing, the adhesive-like material that held the glass to the door frame. This could cause the whole glass unit to loosen and the wood in the door panels to rot.

The introduction of aluminum patio doors

The use of aluminum patio doors provided one big advantage over the use of wood patio doors: they didn't rot. The first aluminum doors were unpainted, raw aluminum.

Although aluminum doors required less maintenance than wood patio doors to keep them from rotting, the aluminum had other annoying shortcomings: it oxidized, and it was very thermally conductive. In winter the door frequently froze shut from warm, moist, indoor air forming condensation on the door frame and contacting frigid cold conducted from outside.

Solutions included painted aluminum with thermal breaks that separated outside aluminum from inside aluminum, and insulated glass. But despite these improvements, in a home with all wood windows an aluminum door stuck out like a sore thumb and detracted from the home's décor.

After sliders, hinged patio doors

When sliding doors became passé, hinged patio doors took center stage. The first was an unpainted door known as an Atrium door, named for its original manufacturer. Hinging it in the middle left only half of the opening available to use for exit and entrance. The doors opened inward, which meant at least half the door swung into the room.

Steel and glass double patio doors

The next trend in patio doors was steel entrance doors with full glass panes. Hinged on both sides, they opened to the full width of both doors. The door had a wood frame that required painting, and the steel door panels were thermally improved to conduct less heat out of the house.

Patio doors, part 2 covers current advanced materials and trends.