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How to Install a Prehung Door

Tearing out a beaten up old exterior door and installing a prehung door improves your home’s appearance. A new insulated door stops drafts too. To learn how to install a prehung door, you’ll need some basic tools and attention to detail.

Steps for How to Install a Prehung Door

  1. First measure the door frame and select a prehung door of the right size.
    1. Be mindful to select one with the doorknob on the appropriate side.
  2. Study the instructions and any warnings on the packaging for the new door.

Removing the Old Door

  1. If a storm door is present, remove its screws with a power drill while a partner holds it. Set is aside.
  2. Score paint and caulk around exterior door trim with the 5-in-1 tool or a utility knife.
  3. Pry off exterior trim pieces.
  4. Take the pins out of the door hinges.
    1. Position the nail set at the bottom of a hinge pin and hit it with a hammer to loosen pin.
  5. With hinge pins out, lift away the old door.
  6. Take out the screws holding the strike plate.
  7. Position the reciprocating saw blade between the old door frame and the house frame.
  8. Saw through all nails and screws around the old door frame.
  9. Starting with the top door jamb, push it loose.
    1. Use the hammer and prybar as necessary to break it free.
  10. Knock free the sides of the old door frame.
  11. You may need to use the prybar to free the old threshold from adhesive.
  12. Take the level and carpenter’s square and confirm that the door opening is square and plumb.
  13. If necessary, nail shims into the frame to create a level surface for the new door.
  14. Take your sill pan kit and attach the pieces to the frame bottom with PVC cement.
  15. Run a bead of caulk along the top and sides of the back of the new door’s brickmould.

How to Install the New Prehung Door

  1. From the outside, set the bottom of the door into the opening and then tilt the door the rest of the way in.
  2. From the inside, insert shims behind the three hinges and on the top, middle, and bottom of the latch side.
  3. Place shims behind the strike plate.
  4. Confirm that the door is centered and plumb.
    1. Adjust shims if necessary.
  5. Starting at the hinges, drill pilot holes and put screws partially into frame.
  6. Add more shims above the screws.
  7. Drive the screws in completely at the hinges.
  8. Now go outside, shut the door and look at the weatherstripping.
  9. If the weatherstripping is connecting with the door inconsistently, adjust fit on the door’s latch side.
  10. At the top and bottom of the latch side frame, partially drive in screws.
  11. Shim them and drive them in completely as you did on the hinge side after confirming the door is plumb.
  12. Shut the door and put a shim in where the strike plate screw will go.
  13. Screw in the final screw at the strike plate.
  14. Set a sheet of paper on the sill and close the door.
  15. Tug out the paper. If it tears, lower the sill cap with its adjusting screws.
  16. If the paper slides out with no resistance, adjust the sill cap upward a bit.
  17. Caulk the edges of the sill cap.
  18. Trim shims sticking out of frame with utility knife.
  19. Pack batt insulation into any gaps around the door frame or use spray foam insulation.
  20. Attach interior trim.
  21. Caulk around interior and exterior trim.

Tools & Materials

  • 5-in-1 scraper tool
  • Utility knife
  • Level
  • Carpenter's square
  • Power drill
  • Pry bar
  • Hammer
  • Reciprocating saw
  • Caulk gun
  • Nail set
  • Wood shims
  • Fiberglass batt or spray foam insulation
  • Exterior-grade caulk
  • Sill pan kit
  • PVC cement

Professional Exterior Door Installation Services

If the steps involved in learning how to install a prehung door seem too difficult or time-consuming, talk to us at PJ Fitzpatrick. We have installed thousands of doors throughout the Delaware Valley. We offer a huge selection of door styles so you’re sure to find the right one for your home. Contact us for a door installation estimate today.

Need help with this project?

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

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