In this video, This Old House general contractor Tom Silva replaces an old entry door with a new door. It’s a relatively easy and fast project that generally requires no special tools (in this case, a hammer drill is used because the bottom of the door fastens to masonry).
For instructions on interior doors, read How to Install a Prehung Interior Door.
How to Install an Exterior Door
The key things to remember are setting the door level, shimming the frame so the gaps between it and the door are even, and taking steps to waterproof the installation.
1. Remove the old door.
- Starting at the bottom, take the hinge screws out of the jamb.
- With all the screws out, take the door from the frame and trash it.
2. Take out the fasteners.
- Remove the screws or nails that hold the old frame in place.
- If there’s interior trim, remove that from the door as well.
3. Flash the frame.
- Install a drip cap or Z-flashing above the opening. The top leg should slide up behind the housewrap or tarpaper that’s behind the siding.
4. Caulk the studs.
- Run a bead of high-quality sealant along the exposed framing where the new door’s exterior trim will meet the wall and across the floor where the door’s threshold will sit.
5. Set the door.
- Insert the new unit top first, sliding the exterior molding up below the Z-flashing.
- Press the unit home so that it beds tightly in the caulk.
6. Set the threshold right.
- With the door in the opening, check the threshold to ensure its level (read How to Choose and Use a Level for a proper reading and usage.) Shim below it if need be until the level’s bubble is centered between the lines.
7. Start fastening.
- Secure the unit with a temporary screw near the top of the jamb’s hinge-side.
- From the inside, check that the gaps between the door and its frame are even. Shim behind the hinges if needed and fasten the frame in the opening with screws behind the weatherstripping.
8. Masonry is harder.
- Sometimes you’ll have to fasten into masonry. Drill screw holes with a masonry bit and a hammer drill (which you can rent) and use special masonry screws to make the connection.
9. Shim the lock-side.
- Screw the jamb to the studs then close the door and look at the gap between the jamb and door.
- Shim it tighter as needed.
10. Caulk away.
- Run a neat bead of caulk between the exterior trim and the siding.
- Once that cures, the door is ready for paint and a lock.
The new door is in. It opens and closes well. Flashing and caulk will keep water out, and the door is ready for paint and hardware.