Parts of the House/ Doors/ Exterior Doors/ Sliding Patio Doors/

How to Put in a Sliding Glass Door


Replace a Single-paned Sliding Glass Door and the Surrounding Dry-rotted Wood and Install an Updated Triple-paned Insulating Door

Replace a sliding glass door and repair the accompanying dry rot that age and weather have fostered on the threshold. After we stop the dry rot, our DIY installation stops the heat loss with a good quality sliding glass door that is triple-paned, energy-efficient, and attractive. Slightly smaller than the original, the door requires resizing the opening with treated lumber.

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removing the top bracket from the stationary door
Step 1

Remove the Fixed Portion of the Old Sliding Glass Door

Loosen the screws in the brackets at the top and bottom of the fixed sliding glass door. Move the door to the center of the track and lift it out.

prying off interior door casing
Step 2

Pry off the Retaining Strip and Door Casings

Pry off the wooden retaining strip from the top of the door opening. Remove the interior door casing/molding. A putty knife and small pry bar can help to remove these components without damage so they can be reused.

removing nails with a nail puller and hammer
Step 3

Extract Nails from the Exterior Trim and Remove the Threshold

Use a nail puller and hammer to extract nails holding the exterior door trim to the house. Remove the threshold and pull the entire door frame away from the opening. Ensure no nails protrude and dispose of the trim properly.

prying up dry-rotted wood exposed under the old threshold
Step 4

Remove All Dry-rotted Material from the Doorway and Threshold

Remove all the crumbling dry-rotted wood around the doorway opening, particularly under the old threshold. Use a crowbar to pry up the disintegrating material until solid wood is revealed as a foundation for repairs.

leveling the new threshold with shims and a bar level
Step 5

Rebuild Threshold Framing with Treated Lumber and Level with Shims

Rebuild the threshold framing with two pressure-treated two-by-six planks secured with a pneumatic nail gun after coating both cut ends (and any untreated lumber) with wood preservative. Use a bar level and shim the planks as necessary to level.

folding the flashing back over the threshold framing
Step 6

Cover the New Threshold Framing with Sheet-metal Flashing

Cover the front and top of the new threshold framing with sheet-metal flashing. Cover the vertical exterior face of the framing first and then fold the flashing back over the top or horizontal face. Secure flashing with galvanized roofing nails.

nailing up treated-lumber spacers to resize the doorway
Step 7

Secure Treated-lumber Spacers to Accommodate the Smaller Sliding Glass Door

Secure treated lumber planks along the top and both sides of the doorway as spacers, if necessary, to fit the new door. Modern sliding glass doors are usually slightly smaller than the older models and may require fitting of the doorway.

caulking the rectangular perimeter of the threshold flashing
Step 8

Caulk the Door's Nailing Flange and the Sheet-metal Threshold Flashing

Bend out the door's nailing flange along its top and sides. Run a 3/8-inch bead of caulk down the center of the nailing flange on the interior side and another bead tracing the perimeter of the rectangular flashing strip.

centering the bottom of the door and tipping it into place
Step 9

Position the New Door and Ensure It Is Plumb

Center the bottom of the new sliding glass door in the opening and tip it up into place. Hammer a single nail through the flange to hold it temporarily ensure the door is plumb. Hammer in the rest of the nails.

replacing exterior door casing
Step 10

Reattach the Exterior and Interior Door Casings

Reattach the original door casings to complete the seal/appearance of the replacement sliding glass door. If you had to resize the doorway opening, you may need to cut new casings for the exterior and/or interior perimeters.

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