Let the Sun In

Mostly composed of glass, French doors admit abundant light. A signature of many 20th-century houses, these doors are called “French” for a reason: Louis XIV essentially invented the prototype when he had 70 floor-to-ceiling casement windows installed in the Hall of Mirrors at Versailles in the 1680s. Hinged so that they open or close from the middle, the glass in the Sun King’s framed casements appear in orderly rows of two, held in place by muntins. These French casements first appeared in the future United States in French Colonial areas in the South, where they opened up to deep porches or colonnades to bring in the breeze.

In the 20th century, Frank Lloyd Wright installed French doors in the Robie House in Chicago, his 1909 Prairie Style masterpiece. Versatile enough to open up a living room to a terrace, or to separate playrooms from bedrooms, French doors quickly caught on during in the residential building boom of the 1910s and ’20s. Stock designs appeared in many kinds of “builder” houses, from Arts & Crafts bungalows to Colonial and Mediterranean Revival homes. Both single and double French doors were chosen for sunrooms, enclosed porches, and sleeping porches because the glazed doors allowed light to reach into the house from sunnier areas without sacrificing comfort.

You can choose traditional French doors with divided lights, but a less expensive option is a door with a single glass panel, accented with simulated muntins. (Marvin offers six options, from removable wood grilles with or without spacer bars to create shadow lines, to authentic divided “lites.”) Even the glass lends itself to customization: choose from beveled glass, privacy glass in any number of clear or frosted patterns, and custom etching or lettering.

Today, glazed doors are an especially popular means of opening up the back of the house to the outdoors. Double glazing and other energysaving features mean glass doors aren’t the heat siphons they used to be. Energy ratings for glass windows and doors are expressed as U-factors; a good U-factor rating is .30 or less.

Today there is much greater versatility in how the door actually operates, too. Period-look doors swing in or swing out in the classic casement configuration, and you can choose pairings with one fixed door and one swinging or sliding door. The ne plus ultra for indoor–outdoor living are door systems that fold, slide, or cascade out of the way, creating a wide opening. Sometimes called bifold doors, these durable units fold on the outside of the house, so they won’t disturb your interior floor plan.

LEFT Choose French doors with real divided lights, or choose real wood applied over a single glass light, as seen in these from Silverado Custom Wood Doors. BELOW Pairs of bifold doors from Marvin feature glazing details that coordinate with the...