How to Install a Prehung Door

By: Charles Wardell, This Old House magazine

Shopping List

Supplies You Will Need

1. PREHUNG DOOR WITH SPLIT JAMS

2. SHIMS
for adjusting and supporting jambs

3. STRIKE PLATE
to protect jamb from latch bolt

4. LOCKSET
to hold door closed

5. 4D FINISH NAILS
to tack shims in place

6. 8D FINISH NAILS
to nail through casing

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Tools List
Tools You Will Need
- Hammer or nail gun,
  to attach casing and jambs to rough opening
- 4-foot level,
  for checking plumb or level
- Drill/driver,
  for fastening hinges
- Tape measure
- 3/4-inch chisel,
  for fine-tuning mortises
- Phillips-head screwdriver,
  for mounting lockset
- Utility knife (for trimming shims
- Retractable plumb bob,
  for plumbing jamb
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Tom Silva taking measurements while installing a prehung door

Photos by: David Carmack

Introduction
Overview
Steps:
- 1
- 2
- 3
- 4
- 5
- 6
- 7
- 8
- 9

1. Check the rough opening

Place a 4-foot level on the floor in the doorway. If the hinge side is lower than the latch side, slip shims under the level nearest the hinge jamb. Adjust the until the level's bubble is centered.

Tack the shims to the floor with a finish nail. If the latch side is lower, no shims are needed.

Check the walls and the trimmer studs for plumb using a level or plumb bob. Also, check the trimmers' faces with a framing square to see if they are square to the wall.

Finally, check that the trimmers are parallel by measuring between them at the top, bottom, and middle of the opening. If the wall is out of plumb, or the trimmers are out of plumb, out of square, or not parallel.