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How to Replace a Patio Door

You’ve finally had enough of your old patio door and want to learn how to replace a patio door. You’re going to put the drafty, sticky, and leaky door in the trash and enjoy a smoothly operating new door. Expect to spend the better part of a day installing the new door. Pay careful attention to the flashing to prevent moisture penetration.

How to Replace a Patio Door Directions

Preliminary measurements:

  1. Pry off the interior trim.
  2. If necessary, remove drywall edges to expose door frame. Use a utility knife and hammer to cut away drywall edge.
  3. Measure the rough opening from stud to stud for the width.
  4. Measure the opening from the subflooring to the top framing beam for the height.
  5. Use the dimensions to order a new patio door.

Installation day:

  1. With the door latched, remove screws holding the inside head stop.
  2. Pull head stop out.
  3. Now unlatch the door and tip the top of the panel inside the house. You can then lift the panel out.
  4. Take off the angle brackets securing the other door panel at the top and bottom.
  5. Slit caulking or paint on the edges of the stationary panel with a utility knife.
  6. Pry the panel loose. Tilt it inside and pull it free.
  7. Step outside and pry away exterior trim.
  8. Now that the door frame is exposed from the outide, fit a long bimetal blade onto a reciprocating saw.
  9. Slide the blade between the door and frame and cut through the fasteners holding it.
  10. Pry the bottom loose from the threshold and tip out the old door parts.
  11. With the framing exposed, use the level to confirm that the threshold is level. If it has bad variations, level them out with shims and caulk.
  12. Starting at the bottom, apply strips of adhesive flashing. Make sure this flashing extends over existing deck flashing or weather barriers.
  13. Flashing needs to extend at least 2 inches up the sides.
  14. Prepare the sill pan by cleaning the joint overlaps with PVC cleaner.
  15. Set the sill pan parts in place and glue the seams with PVC cement.
  16. Assemble the new door frame and dry fit it in the frame.
  17. Spread two beads of silicone caulk along the threshold.
  18. Tip the frame into the opening.
  19. Center and square the frame, using shims as necessary.
  20. Nail flange along the edges.
  21. Place adhesive flashing over the flange. This is an important part of how to replace a patio door because it protects the door from leaks.
  22. Drive screws into the frame to secure the door.
  23. Tip in the stationary panel first.
  24. Secure it with angle brackets.
  25. Tip in the moving panel and attach the head stop.
  26. Adjust the door roller heights as necessary.
  27. Attach the handle hardware.
  28. Push strips of fiberglass insulation into gaps between door and frame.
  29. Fill gaps with caulk.
  30. Install extension jambs.
  31. Measure and cut a threshold support block. Nail it in place.
  32. Install new interior and exterior trim.

Tools & Materials

  • Measuring tape
  • Utility knife
  • Pry bar
  • Screwdrivers
  • Power drill
  • Hammer
  • 4 ft. level
  • Caulking gun
  • Reciprocating saw
  • Table saw
  • Miter saw
  • Finish nail gun

Save Time with PJ Fitzpatrick

Replacing the door yourself would be satisfying, but you might have better uses of your time. PJ Fitzpatrick has been installing doors for decades. We can schedule installers to visit your home and complete the job quickly. Ask us for a door installation quote today.

Need help with this project?

We have trained professionals that can help. Contact us today. 1-877-246-4354

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