How to Install Split-Jamb Interior Doors
Time Required: Under 2 hours
Split-jamb prehung doors work well in situations where the rough frame is wider than a standard opening. They feature jambs that are split in half lengthwise, and the trim casing is already attached to each edge of the jamb, so no mitering is necessary.
Split jamb door installation is different than other interior doors, since each half of the jamb is installed separately, beginning with the side that holds the hinges. This guide explains how to install split-jamb doors in your home.
Tip: When ordering any pre-hung door, make sure you specify the wall's overall thickness, and remember that the jambs ordered for plaster-covered walls are different than those for walls finished with drywall.
- Choose whether you want the door to swing open to the left or to the right.
- If you are left-handed, consider having the knob on the left when the door opens to you.
- If you are right-handing, consider having the knob on the right when the door opens to you.
- Have a partner help while you center the door into the opening.
- Insert the bottom first, then lift the top into place.
Tip: If you are staining or painting your door after installation, it should be sealed with two coats on all 6 sides, including the edges. This will restrict moisture penetration.
- Open the door and work from the inside.
- Block and shim the jamb at the hinge locations and above the jamb with 8d finishing nails.
- If your door is larger and has more hinges than a standard door, you’ll need to use additional shims above each hinge.
- Double check and make sure the door is still square and plumb. Adjust the shims as needed.
- Follow these same steps to shim the jamb on the lock side of the door.
Tip: If you’re using tapered shims, alternate the direction in which they are inserted.
- Work from approximately 6-inches below the top of the frame, and drive 8d finishing nails into the hinge side of the frame.
- Penetrate through the jamb and shim, making sure the frame remains square and plumb.
- Drive another nail approximately 6-inches above the bottom of the frame, and the third nail into the middle.
- Follow these same steps to secure the lock side of the door.
- Use a shim behind each nail, and trim them with a utility knife when this task is complete.
- Slide the second part of the frame into place.
- Nail through the jamb stop and secure them together.
- Secure the trim to the wall with two side-by-side nails every 12-inches top to bottom.
Tip: Do not drive the nails fully into the frame in case they need to be removed in the future.
- Remove the nails from the top and bottom of the frame
- Use a hammer to tap the frame over using a hammer until the gap is closed.
- Re-nail the frame to secure your final adjustments, and countersink the nails that were left in place.
- Install the door know and lockset, if applicable.