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.
- The first step is choosing the correct door to install.
- Like slab doors, split-jamb doors can come in a variety of styles and sizes, so measure your opening and choose one that fits your space.
- 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. Similarly, if you are right-handed, you will likely want the knob on the right when the door opens to you.
- If you are right-handed, 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 six 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 will have to use additional shims above each hinge.
- Double-check to make sure that 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 use tapered shims, alternate the direction in which they are inserted.
- Work from approximately six inches below the top of the frame, driving 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 six 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 together.
- Secure the trim to the wall with two side-by-side nails every 12 inches from 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 into place, 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 knob and lockset, if applicable.