PHOTOS BY SCOTT JACOBSON

A staple of many American homes, a patio door is more than just an entry point; it's also a focal point that projects a sense of openness and a blending of the outdoor environment with a home's interior. The large openings that most patio doors provide enhance ventilation and natural light as well as accessibility, making them ideal entryways for a multigenerational family where barrier-free accessibility is a concern.

Unfortunately, however, the doors' size can also be a drawback when it comes time to replace them. And these doors inevitably show the passage of time: Glass panels' seals fail and create air leaks, door frames sag or rot, and styles eventually become dated. Although installing a new door may seem daunting — after all, it's heavy and bulky, and if you drop it, the glass can shatter — the challenge isn't gargantuan. With a little planning and preparation, the right tools and the help of a friend or family member, you can swap out an old door for a new energy-efficient model in about a day, and you'll reap the benefits for years to come.

Step by Step
Before you install a new patio door, you'll need to remove the old one. In the case of a sliding unit, start by lifting out the screen and the sliding glass panel. Remove both the interior trim and exterior molding; then cut away a 3-1/2-in.-wide strip of the exterior siding (photo 1). Remove the nails or screws or use a reciprocating saw to cut through any that were driven through the door's frame; then recruit a friend and, working from the outside, gently tilt the old door out of its opening.

Check that the opening is 3/4 in. wider and 1/2 in. taller than the new door, and verify that the opening is both plumb and square. Use a handheld planer to remove any high spots in the framing (photo 2); then add any necessary blocking. (For example, we had to add sill support, as the new door's sill was wider than the old sill.)

Cut strips of sill-flashing tape 12 in. longer than the rough opening's width and apply it along the bottom so that it overhangs 1 in. to the exterior and extends 6 in. up each side. Overlap the strips by at least 1 in. until you've covered the entire sill; then apply three 3/8-in.-thick beads of silicone sealant atop the flashing tape, following the door manufacturer's recommended spacing (photo 3).

After you've unpacked the new door and removed the screen and the sliding glass panel, insert the new door from the exterior of the building into the opening (photo 4). Place the bottom of the door at the bottom of the opening; then tilt the top into position — do not slide the bottom of the door into the opening, as sliding will damage the sealant lines. Center the door between the opening's sides to allow for equal clearance for shimming. To hold the door in place while you make it plumb and square, drive one roofing nail into the first hole from the corner on each end of the top nailing fin.

Make sure that the door is plumb and square (photo 5), inserting any necessary shims between the door and the sides of the rough opening, starting 6 in. up from the sill. Then fasten the door to the opening by driving 2-in. galvanized roofing nails into each of the punched holes in the nailing fins (photo 6).

Apply flashing tape over each of the side nailing fins, extending the tape 2 in. above the top of the door and 2 in. below the bottom (photo 7). Cover the top nailing fin with a strip of flashing tape that extends at least 1 in. past each of the side flashing tape strips. To prevent water penetration, make sure that the top flashing tape overlaps the side flashing tape. Finally, reinsert the sliding glass panel into the door frame and install any remaining door hardware.

From inside, apply a 1-in.-deep bead of low-expansion foam sealant in the gap between the studs and the door frame (photo 8) and let it cure; then check for proper operation by opening and closing the door. If the door doesn't operate smoothly, check to make sure it is still plumb, level and square and that the sides are not bowed. If adjustments are necessary, remove the foam with a serrated knife, adjust the shims and reapply the insulating foam sealant.

All that's left is to attach the exterior moldings and the interior trim. But keep your tools handy — when the friend who helped you sees the results, he might ask you to return the favor at his house.

Suit Your Situation
Though sliding glass-panel doors are the most common type of patio door, other options such as French doors, pocket doors and bifold sliding doors are available in a variety of sizes, and you can have doors custom-built to fit any opening. We worked with technical advisors at Pella Windows and Doors to design and install both a sliding patio door and a French door system that would complement not only the house but its environment as well. To match the home's existing woodwork, we opted for Pella's mahogany Architect Series doors. The divided lights add a touch of sophistication to the doors' overall appearance, and to keep future maintenance to a minimum, we decided on a matching-color aluminum-clad exterior.
All About Transoms
A transom is a fixed or operating window set above another window or a door. Besides increasing visual interest, transoms can increase natural light in a room and provide additional ventilation (depending on their design). In cooler climates, a fixed transom can help with passive heating, provided it is installed in an area that receives a good amount of sunlight. In warmer climates, an operating transom can help with cooling by releasing hot air that would otherwise stay trapped near the ceiling. If you would like to add a transom above a sliding- or a French-door system, you'll need to modify the rough opening and raise the opening's header to accommodate the additional height. For the Pella French door and transom system we installed, we were able to download complete architectural specifications from Pella's Web site to aid in the framing modifications. Most manufacturers should be able to provide the necessary installation information, but if you're unsure about the process, don't hesitate to consult a professional contractor — it's essential that you avoid creating a weakened wall that won't adequately support the door and transom unit.


Sources
Pella Windows and Doors, 800-374-4758