As a young carpenter working on a condo project, I gained a good bit of experience installing 6-foot-wide sliding glass doors. The builder-grade units came fully assembled, and once we got past the hurdle of hauling them to the right room, installation was just a matter of laying down a bead of silicone on the floor, lifting the door into position, cross-taping it to make sure it was square, and screwing the nailing flanges to the wall sheathing. The doors functioned well when they were new, but years later, I noticed on a return trip for a remodeling project that many had been replaced with hinged units.

Recently, we installed a much larger sliding glass door unit as part of a kitchen remodel and patio addition. The client was opening up the interior floor plan, replacing the kitchen cabinets, and adding a roof over a large patio off the kitchen, but a major part of the project was replacing the existing windows and a door separating the kitchen from the patio with a 16-foot-wide-by-8-foot-tall sliding glass door. Sliding the two 4-foot-wide center operating panels open created an almost 8-foot-by-8-foot opening that extended the kitchen space outdoors.

Complicating the project, a large beam—installed as part of a previous remodel and carrying considerable roof and ceiling loads—was buried in the bearing wall that we needed to remove to install the new door unit. Supporting the exterior roof loads and the interior beam while we made a 16-foot-wide rough opening was going to be a tall order. Since we needed engineering to size the new header, I looked for a simpler solution.

Applied beam. Working together with the engineer we had hired to come on site to calculate loads and help with beam sizing, we came up with a plan to glue and lag-bolt a new, long beam capable of supporting those loads to the inside of the wall before we opened it up for the new door. After supporting the beam and framing the new rough opening with a new 2x4 wall inside the old wall, we would be able to tear out the existing wall to complete the rough opening. Not having to tear out the old wiring to get the new header in place was a bonus. My client was fine with losing about 5 inches out of the large kitchen if it saved her time and money on the framing.

In order to frame the opening for a new 16-foot-wide door, the author first stripped the drywall from the existing wall, then applied construction adhesive to the framing where a new, 16-inch-wide LVL beam would be located.
Workers used a 3-ton trolley jack and a series of supports in graduated lengths to slowly and safely lift the heavy beam into position.

Getting the 20-foot-plus-long-by-16-inch-deep LVL in place wasn’t much fun, but it would have been a lot harder going into the exterior wall with temporary supports everywhere. After the LVL was installed, the engineer’s design called for building up the beam thickness with layers of plywood glued and screwed to the LVL to match the 3 1/2-inch-wide wall framing.
As soon as the beam was complete, we removed the original windows and door, framed in the new rough opening, and called in the electrician. Because we were over a month out on delivery of the door, we filled in the hole with a temporary wall as soon as the electrician was finished.

Once the 1 3/4-inch-wide LVL was fastened to the framing with LedgerLok structural screws, alternating layers of 3/4-inch and 1/2-inch plywood ripped to width were added to the assembly with glue and screws until the beam measured 3 1/2 inches thick.
With the rough framing and wiring completed and new drywall hung, workers closed in the opening with a temporary wall to weatherproof the opening until the new door arrived and could be installed.

Door installation. The door arrived as four panels and a carton full of frame and track pieces. I waited for a warm, dry day and headed to the job with part of my crew to remove the temporary wall. Our next step was to screw the frame together (pro tip: make sure you use all the parts included for joining the frame). Since the project included a new, 14-foot-deep roof over the patio off the kitchen, we weren’t too concerned about long-term waterproofing, but I did need to make sure the installation was airtight. We carefully scraped all the old caulking off the slab and checked for high spots with a level before carrying the frame outside.

The new door arrived disassembled, so the frame had to be screwed together prior to installation, and part of the new tile floor had to be trimmed back to accommodate the door frame.
A worker used a chisel to remove dried construction adhesive that had been used to glue the old wall plates to the concrete slab floor.

To prevent any air leaks under the sill, we prepped the opening by laying down a heavy double bead of silicone sealant on the slab floor and partway up each wall. We also applied sealant to the frame before screwing the two outside panels into place, then lifted the assembly. That made the door frame a lot heavier and harder to lift in place, but the result was a better installation (the right way usually is harder). To make the job easier, we used a 2x4 as a lever to lift each end up and over the sealant before bedding it down.

After checking for dips and high spots (above), a worker applied a couple of beads of 100% silicone sealant to the slab for bedding the sill (right).

For sliding doors to fit and operate properly, the frame has to be perfectly both plumb and square. We started by carefully plumbing the door jambs, putting a few screws in the corners to hold them in place. Next, we used an 8-foot level to check for high spots in the bottom track, then cross-taped to check the diagonals for square.

Sealant was also applied to the door frame before the outside panels were installed and screwed to the frame (left). Workers used a 2x4 to lever the heavy door into position and lower it onto the sealant (above).
Next, the crew checked that the door sill was level (above) and that the jambs were plumb (right) as they adjusted the frame in the opening.
Workers measured the diagonals and made adjustments as needed to make sure that the diagonals matched and the frame was perfectly square before completing the frame installation.

The last step in setting the frame was to make sure the top was straight. To do this, we used the 8-foot level again but also double-checked by climbing up a ladder to sight along the whole top before running screws through the top flange. While doing this, we noticed that lifting the frame in place had caused one of the fixed panels to shift a little, which we fixed by wedging a 2x4 against the other fixed panel and applying a little pressure.

After checking the head jamb to make sure it was straight and level and screwing the door’s nailing flange to the sheathing, a worker sets one of the removable panels onto the bottom track and installs the upper guide, which holds the panel in place (left). Then he inserts shims between the door frame and the header to ensure that the upper track is straight (above).

Rollers on the bottom of each operating panel allow them to glide along the bottom track, but the tops of the panels are held in place with removable guides. To set an operating panel, you start at the bottom then stand the panel up, slide the upper guide in place, and mount it with screws, repeating the process for the second panel.

Rubber bumpers that snap down over the lower track keep the sliding panels from hitting the jambs (above), while small L-brackets help to fasten the fixed panels to the frame (right).

On our installation, both panels rolled very smoothly, but it’s possible to make adjustments if necessary by tweaking the rollers, which are independently adjustable, under each end of the doors. We added a few shims to make sure the inside edge of our track was straight, then angle brackets to secure the fixed panels to the frame before installing the bumpers. We finished up the installation with a wood trim strip screwed in place to cover the upper track.

To finish up the door installation, the worker installs a wooden trim strip that covers the upper track (left). The installed door is now ready for extension jambs and trim. The author will wait to install the door hardware until after the paint crew finishes their work (above).

I didn’t want to install any lock hardware until the painters finished, so we went old school and just cut 2x4s to drop in the track for a lock. About a week later, we returned and foamed around the frame with low-expansion foam. Then we added jamb extensions to make up for the added wall thickness and added casing trim.

Back in the day, we could have installed five smaller door units in the amount of time it took to complete this one extra-large one, but I am pretty sure if I come back to remodel this house in 20 years, the XL door will still be there and sliding as well as it does today.

Photos by Gary Striegler