If you’ve dreamed of opening French doors–doors with glass panes throughout–to your patio or garden, you’re in luck. There is more variety in them than ever before. But finding the right ones for your taste and pocketbook can be a challenge: The range of door materials and decorative options is vast and varies a great deal from one manufacturer to another. Here’s what you need to know.

Materials

French doors are commonly available in wood, steel, aluminum, and fiberglass. Some wood doors are covered with aluminum or vinyl. Most manufacturers produce one or two of these door types.

Each door material has its advantages and disadvantages. “Metal- and aluminum-clad doors need less maintenance over time, but wood provides a higher quality, more traditional look,” says Tom Lawrence, of Lawrence Architecture in Seattle.

Although an issue for all French doors, leakage is of particular concern with wood doors. “Once a wood door becomes exposed to moisture, it warps and starts to expand. Then it can easily start to stick,” says Berkeley-based architect Gary Earl Parsons. Vinyl stands up to rain but can become brittle from exposure to UV rays.

Some door materials are noisier than others. Steel doors clang and aluminum doors make less noise, but wood is the quietest.

Glazing

Whether you want to protect against solar heat gain, prevent heat loss, or simply create a more decorative effect, there is a glass available to suit every situation. Insulating (including argon gas–filled), tinted, noise-deadening, tempered, distortion-free, impact-resistant, opaque, and translucent glass are just some of the possibilities.

For many manufacturers, insulating glass is standard; with others it is available upon request. Some manufacturers offer a range of energy-efficient glazing options.

Lights

Each pane of glass in a French door is referred to as a light. Single-light doors have one undivided panel of glass. Doors with divided lights have smaller areas of glass separated by muntins (wood or metal bars).

In true divided lights, the small panels are actually separate pieces of glass. This may be the most authentic-looking option, but the style is prone to leakage and many manufacturers no longer offer it. An alternative is simulated divided lights, which mimic the traditional look while maximizing energy efficiency. Simulated divided lights may have snap-in grilles on the insides of the door or permanently attached muntins on both the interior and exterior. If you’re ordering double-paned glass, manufacturers can insert aluminum, wood, or plastic spacer bars or grilles between the panes of glass.

When deciding between single or divided lights, consider the style of your home. Traditional wooden divided lights may look strange on a sleek modern house. For such a house, steel or aluminum doors with undivided expanses of glass may be a better choice.

In-swinging or out-swinging doors

The majority of manufacturers now offer both in-swinging and out-swinging French doors. The decision to choose between them is usually dictated by location. “An outside-opening door is often a lot nicer because it doesn’t take up so much space on the inside. But for protection from the weather, it’s especially important that such doors be covered by overhangs,” says architect Karl G. Smith, of San Francisco.

“They’re still not the dominant design, but out-swinging French doors are much more prevalent than they were several years ago,” says Alan Campbell, president of the Window & Door Manufacturers Association. This is due in large part to new hardware and hinging devices that make out-swinging doors more watertight.

Installation

Leakage and warping must also be taken into account when you’re ready to install (or have installed) a set of French doors. Do-it-yourself installation in a new opening can be risky because cutting through the wall may create waterproofing problems. “Sometimes the waterproofing membrane in a wall is so brittle that it falls apart and needs to be replaced,” says contractor Michael Muscardini of Creative Spaces in Oakland, California. A qualified contractor will anticipate such problems.

To protect against leakage, look for doors with multipoint locking systems (pinned at the top, bottom, and center) that will keep them square and thus watertight. Also ask for factory-installed weather-stripping, which is available on most doors. If you decide to install French doors yourself, be sure to follow the manufacturer’s instructions. “Sometimes people will buy a prepackaged wood door, and then if it doesn’t fit, they’ll start to cut away at it. What they don’t realize is they’re removing preservative that keeps the wood from warping,” says building code consultant Julie Ruth of JRuth Codes Consulting in Chicago.

Custom doors

Every manufacturer has a menu of available doors and options. This menu is not uniform within the industry Some offer a wide variety of sizes and types as standard doors, which are usually in stock and available for immediate purchase. If you want a size or type not available in the manufacturer’s inventory, it can often be ordered, but delivery may take longer. Other manufacturers make all of their doors to order. If you are considering an unusual size or material, you may want to go with a manufacturer that custom-makes all of its doors. As a general rule, if you want a door to be more than 4 feet wide or 8 feet tall, you will need a custom door.