How To Install A Sliding Glass Door
Glass sliding doors are an attractive feature in any home. But, they do require maintenance or replacement over time. If considering a new sliding glass door, a number of new features and benefits are available. Privacy features include upgraded security lock hardware, tinted glass, and between-the-glass shades and blinds. New sliding glass doors securely install weather tight, look great and last for years. Other new options for sliding glass doors can incorporate triple-paned glass, energy-efficient frame construction and better sliding mechanisms. If it’s time to replace that old worn out slider, here’s how to get started.
Remove The Existing Door & Frame
Remove the sliding glass door by lifting it out of the tracks. Loosen the screws in the brackets at the top and bottom of the fixed sliding glass door with a screwdriver or drill motor. Move the fixed door to the center of the track and lift it out. Remove the interior casing or molding. Next remove the exterior casing pieces and set aside for later use. Use a utility knife to cut around the caulk and paint, then use a wide putty knife or thin pry bar to slowly loosen and remove each molding piece to avoid damaging them. You will need them later.
Remove the entire threshold and the doorframe away from the door opening. A handy tip for finding hidden nails is to use a stud finder or magnet to point to the nail locations. Then locate the nails holding the doorframe and the trim pieces into the wall studs and header. Remove the rest of the nails with a claw hammer or nail puller. Carefully inspect the studs and subfloor for signs of dry rot, water damage or any other existing problems.
Install A New Threshold & Flashing
If the repair requires a new threshold, rebuild it with pressure treated lumber and level the new threshold with shims. Use a 4-foot level or the longest one available to set and shim the threshold. Cover the new threshold with sheet metal flashing. Secure the flashing with galvanized nails and calk as needed. Double check the threshold is level.
Measure the rough opening from stud to stud and from header to threshold for height and width. Also measure from diagonal corners to confirm the opening is square. If the opening is not square, now is the time to shim the studs and get it into square.

Install The New Sliding Door Frame
Bend out the sliding door’s nailing flange along the top and sides. Run a 3/8-inch bead of caulk down the center of the nailing flange on the interior side and a second one around the perimeter of the rectangular flashing strip.
Lift the new doorframe into place and secure with a single nail. Check the frame for plumb, shim as needed on both sides. Once the frame is plumb, hammer the rest of the nails into the frame. Calk the exterior seals well with silicone sealer.
Install The New Sliding Door
Lift the fixed glass door into position and secure in place by following the manufacturer’s instructions. Attach the brackets at the top and bottom of the fixed door with a screwdriver. Lift the sliding glass door into position. Adjust the rollers to fit into the tracks and check that the movement is smooth and does not bind. Attach any additional hardware required to the frame and slider.
Reattach Molding & Trim
If the new sliding glass door is a different size than the old one it will be necessary to cut new pieces of molding or door casing for the interior and exterior molding. If the door is the same size as the old one then you’re nearly finished.
Now is the time to sand and prepare the interior molding. Reattach the molding pieces with finish nails. Putty the nail holes and paint the interior and exterior trim molding.
Tools You’ll Need
- Measuring tape
- Caulk gun
- Silicone caulk
- Combination square
- Dust Mask
- Hammer
- Galvanized nails
- Circular saw or handsaw
- Miter saw for cutting new molding (if needed)
- 3 or 4-foot level (longer is better)
- Reciprocating saw
- Screwdriver
- Variable-speed drill
- Safety goggles
