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.
Tools and Materials
- 5-in-1 scraper tool
- Utility knife
- Carpenter’s square
- Power drill
- Pry bar
- Reciprocating saw
- Caulk gun
- Nail set
- Wood shims
- Fiberglass batt or spray foam insulation
- Exterior-grade caulk
- Sill pan kit
- PVC cement
Steps for How to Install a Prehung Door
- First measure the door frame and select a prehung door of the right size.
- Be mindful to select one with the doorknob on the appropriate side.
- Study the instructions and any warnings on the packaging for the new door.
Removing the Old Door
- If a storm door is present, remove its screws with a power drill while a partner holds it. Set is aside.
- Score paint and caulk around exterior door trim with the 5-in-1 tool or a utility knife.
- Pry off exterior trim pieces.
- Take the pins out of the door hinges.
- Position the nail set at the bottom of a hinge pin and hit it with a hammer to loosen pin.
- With hinge pins out, lift away the old door.
- Take out the screws holding the strike plate.
- Position the reciprocating saw blade between the old door frame and the house frame.
- Saw through all nails and screws around the old door frame.
- Starting with the top door jamb, push it loose.
- Use the hammer and prybar as necessary to break it free.
- Knock free the sides of the old door frame.
- You may need to use the prybar to free the old threshold from adhesive.
- Take the level and carpenter’s square and confirm that the door opening is square and plumb.
- If necessary, nail shims into the frame to create a level surface for the new door.
- Take your sill pan kit and attach the pieces to the frame bottom with PVC cement.
- 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
- From the outside, set the bottom of the door into the opening and then tilt the door the rest of the way in.
- From the inside, insert shims behind the three hinges and on the top, middle, and bottom of the latch side.
- Place shims behind the strike plate.
- Confirm that the door is centered and plumb.
- Adjust shims if necessary.
- Starting at the hinges, drill pilot holes and put screws partially into frame.
- Add more shims above the screws.
- Drive the screws in completely at the hinges.
- Now go outside, shut the door and look at the weatherstripping.
- If the weatherstripping is connecting with the door inconsistently, adjust fit on the door’s latch side.
- At the top and bottom of the latch side frame, partially drive in screws.
- Shim them and drive them in completely as you did on the hinge side after confirming the door is plumb.
- Shut the door and put a shim in where the strike plate screw will go.
- Screw in the final screw at the strike plate.
- Set a sheet of paper on the sill and close the door.
- Tug out the paper. If it tears, lower the sill cap with its adjusting screws.
- If the paper slides out with no resistance, adjust the sill cap upward a bit.
- Caulk the edges of the sill cap.
- Trim shims sticking out of frame with utility knife.
- Pack batt insulation into any gaps around the door frame or use spray foam insulation.
- Attach interior trim.
- Caulk around interior and exterior trim.
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.