Replacing just the door slab (the door itself, leaving the existing frame and hardware) is the easiest door swap — far simpler than replacing a complete pre-hung door. The job is essentially: remove old door, transfer hardware to new door, hang. The catch is matching the new door to the existing hinge cuts and lock bore. Stock doors come pre-bored; specialty doors may need bore work.
This guide covers a slab door swap. Pre-hung door installation is covered separately.
Before you start
Three things to settle:
1. Slab vs pre-hung. Slab door: just the door, no frame. Used to replace existing doors where the frame is in good condition. Pre-hung: door already mounted in a frame. Used for new construction or when the frame is damaged. Slab is much easier; verify your situation.
2. Match standard sizes. Standard interior doors: 24, 28, 30, 32, 36 inch widths × 80 inch height. Older homes (pre-1970) may have non-standard sizes (often 1/4 inch off). Measure your existing door before buying.
3. Hinge and bore positions. If buying a pre-bored slab matching the existing door's hinge and bore positions, the swap is plug-and-play. If buying a blank slab (no bore work), you'll need to drill bores and cut hinge mortises — significant additional work.
What you'll need
Tools
- Hammer
- Pry bar (small)
- Drill with bits
- Phillips screwdriver
- Wood chisel and mallet (for hinge mortises if needed)
- Hole saw (for door knob bore if needed)
- Tape measure and pencil
Materials
- New interior door slab (matching existing size and bore configuration)
- Wood shims (if door fit needs adjustment)
- Wood filler (for any mortise issues)
Buy pre-bored slab matching existing
When buying a slab to replace an existing door, look for 'pre-bored' or 'machined' — these come with hinge mortises and lock bores already cut. Match to your existing door's specs (width, height, hinge spacing, lock bore location).
Blank slabs (no bore work) require significant additional carpentry — chisel hinge mortises, drill bore. Skill-intensive and time-consuming.
Step-by-step instructions
Remove the existing door
Pop the hinge pins by tapping them up from below with a hammer and small nail.
Once all pins are out, lift the door free of the hinges.
Set the door aside — useful for measuring against the new door.
Transfer hinge positions
Lay the new door next to the old door, with the hinge sides aligned and the doors at the same height.
Mark the new door's hinge mortise positions matching the old door. Verify by direct alignment, not just measurements.
Verify pre-bored mortises align
If the new door is pre-bored, check that the mortises align with the existing frame's hinges.
Slight differences (within 1/4 inch) can be addressed by repositioning hinges or adjusting screw locations.
Major differences mean the new door doesn't match this frame — return for a different door.
Install hinges on new door
Transfer the hinges from the old door to the new door (or buy new hinges if updating).
Drive screws through hinges into the door's mortises. Snug — don't over-tighten.
Hang the new door
Lift the new door up to the frame's hinges. Align the door's hinge knuckles with the frame's hinge knuckles.
Drop hinge pins through both knuckles and into the bottom of each frame hinge.
Verify all hinges are seated.
Test the door swing
Open and close the door fully. The door should swing freely without binding on the frame, head jamb, or floor.
If binding: identify where (top, bottom, side, latch). Adjust by sanding the door's edge OR re-hanging with shims.
Install the door knob/lever
Most pre-bored slabs have the standard 2-1/8 inch face bore and 2-3/8 inch backset. Standard knobs install directly.
Insert the latch into the door's edge bore. Insert the knob's outside half through the face bore. Attach the inside half. Tighten the through-screws.
Adjust the strike plate if needed
If the new door doesn't latch cleanly, the strike plate on the frame may need slight repositioning.
Loosen strike plate screws, shift the plate up/down or in/out, retighten.
Final inspection
Door should open, close, and latch smoothly without binding.
Door's edge should align with the frame's edge — no visible step.
Hinges should be flush with their mortises — no gap between hinge plate and door surface.
Common mistakes that cost you
- Wrong door size. Even 1/4 inch off causes binding or gaps. Measure existing carefully.
- Pre-bore positions don't match. Mortise/bore in wrong location means the door doesn't fit the frame. Verify before buying.
- Loose hinge screws. Door sags. Tighten firmly; replace stripped screws with longer ones bit into framing if needed.
- Strike plate not adjusted. Door doesn't latch cleanly. Adjust strike plate position to match new latch alignment.
Frequently asked questions
Can I install a slab door without removing the frame?
Yes — slab swap is the easiest door replacement. The frame stays; only the door is replaced.
Useful when the frame is in good condition and you want a different door style or want to repair a damaged door.
What if my door size is non-standard?
Older homes (pre-1970) often have non-standard door sizes. Custom doors are available from millwork specialists.
Alternative: buy a slightly larger standard door and trim to fit. This requires careful measurement and edge-trim work.
How do I cut a non-pre-bored slab?
Mortise the hinge cuts using a chisel and mallet. Drill the lock bore using a hole saw. Drill the latch bore (smaller diameter) on the door's edge.
Significant carpentry skill needed. For most homeowners, buying a pre-bored slab is the right call.
When to call us instead
If your door frame is damaged, out of square, or you're upgrading to a different door style, professional installation produces consistent quality. We do door work as part of larger renovations.
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If you're updating doors throughout a home, our residential renovation team handles door installation as part of fixed-price scopes. Book a free 60-minute consultation.