Remodeling 19: How to Replace a Sliding Patio Door

In conversing with a member of our site, recently, I was shocked to hear that he was quoted $900 for labor to remove an existing patio door and replace it with a new unit. I sent him these instructions, hopefully they will help you too.

Here are the steps to remove and replace a sliding patio door unit with the same size unit:

Diagram of a sliding patio door showiwng trim, threshold, nailing flange and adjustment screws.

1. Remove the window liner of the patio door and casing from the inside.

2. Removing the existing patio door: If the house is stucco, by using either a circular saw or an angle grinder with a masonry blade, remove the stucco about 1 1/2" from all around the patio door unit. These patio door units have a flange on them that is designed to hold the patio door units against the sheathing on the wall. You have to remove the stucco, siding and trim for the first 1 1/2" around the patio door unit, right down to the sheathing, to expose this flange. Get a nail claw and remove the nails driven through the flange into the sheathing. I remove the sliding patio door to make the frame lighter. Lift up and out on the bottom when the patio door is in the full open position. The new patio doors have stop blocks in the frame header which prevents upward movement unless the patio door is opened enough to slide by these blocks. Older patio door units do not have these. Remove any screws through the frame into the cripple, especially around the latch. Remove the patio door frame unit.

3. Replace the new patio door unit - Set the new patio door unit in position on the sub-floor and shim up one side to level the patio door unit. Shim up under the patio door unit in various places to keep the threshold level. A helper is usefull here to keep the patio door unit from falling out. I usually work by myself so use nails as a third hand, by nailing the nails above the upper flange, enough to allow shiming (if required), and bend them over the flange to prevent the top from tipping out. When the bottom threshold is straight and level nail the bottom flange about 6" apart. Aluminum flanges have a thin groove to nail through, vinyl flanges have elongated holes to nail through. Use roofing nails to nail the flanges, especially on vinyl, center the nail in the slot.

4. Plumb the side of the patio door unit by installing the patio door back in and close the patio door to get an even margin. This should require very little movement and should be perfect from the patio door manufacturer. It stands to reason that if the bottom is level the sides should be plumb as long as the patio door unit is square. If it is not, the patio door may need to be adjusted if the side frames look plumb with a level. The patio door is levelled using a screw driver on the sides on the bottom, through a hole. By screwing this screw in or out will lift or drop this side of the patio door. Keep trying until the patio door slides against the jamb evenly. That's why it is important to level the patio door base well before continuing, so that the patio door will roll along the bottom nicely and straight rather than going up and down and rubbing on the track. When happy with the patio door unit being plumb, nail up the side flanges on both sides.

5. Remove the nails above the top flange used to temporarily hold the patio door unit at the top. Do not nail any nails in the top flange at all. The top is held against the sheathing with the trim or siding and allows the header to move down without breaking the patio door unit as the wood shrinks. This is mainly for a new house where the lumber still has a percentage of water in it. Still good practice, though.

6. Open and close the patio door and adjust if necessary.

7. Depending on the type of siding or stucco, you have to replace or install a 1x4 trim on the outside of the patio door. Pack out above the flange to match the thickness of siding or stucco, usually a ripping of 5/8" plywood works nicely ripped about 1 3/8" wide. The trim will cover the flange and provide shelter from the elements. Caulk the frame to the trim and trim to the siding or stucco, unless it is bevel siding. Use an exterior latex with silicon caulking that is paintable, for example Alex Plus by Dap.

8. Insulate between the patio door unit and the cripple (jack stud), threshold and header loosely with fibreglass insulation or the spray foam. Finish the inside liner as was the original and install the casing. Caulk up the casing with the same as used outside.

Enjoy your new patio door.


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