If you need a new interior door but don't want to remove the existing door frame and trimwork, your only choice is to install what's called a slab door. A slab door is just that: a door panel without an attached frame or hinges installed as found on a prehung door. It's typically made of wood, steel or a composite material, and may be solid or have a hollow core.
Before You Install an Interior Slab Door
Installing an interior slab door is a job best left to a professional, because extreme care must be taken in order to ensure a proper, level fit. If you're handy with tools and have made similar home improvements, however, you can install an interior slab door by yourself. To do so, you'll need these supplies:
- A slab door the same size as your current door
- Doorknob hardware (lockset)
- Lockset hole saw kit with pilot bit
- 3/8-inch drill bit
- 7/8-inch spade bit
- Utility knife
- Tape measure
- Pencil to mark measurements
The first thing you'll want to do is remove the existing door from the door frame. Don't discard the old door yet; you'll need it to mark the positions for the hinges and lockset on the replacement slab door. You'll also need to measure the dimensions of the door you're replacing in order to purchase a new slab door that fits properly. Check out About.com's Home Renovation channel for information on the difference between prehung and slab doors.
How to Install an Interior Slab Door
- Using the old door as a guide, take your pencil and mark the new door with the position of the hinge mortises, latch hole and doorknob (lockset).
- Attach the 3/8-inch drill bit to your drill. Drill a shallow guide hole in the face of the slab door to mark the center of the hole where the door handle will be inserted.
- Drill a shallow guide hole in the edge of the door where the center of the latch hole will be positioned.
- Attach the hole saw to your drill. Cut the opening for the lockset in the face of the door, using the hole you made in step two to position the pilot bit. Press firmly as you drill, making sure you're going in straight. Pause often and clear out the sawdust. Stop cutting when the pilot bit of the hole saw pokes through through the other side of the door, but before the teeth of the hole saw break the surface.
- Switch to the other side, inserting the pilot bit into the hole, and finish cutting the opening. If you cut the hole from one side only, you're likely to have ugly tearout and splintering on the door surface.
- Attach the 7/8-inch spade bit to your drill. Using the guide hole on the edge of the door that you made in step three, drill a hole through to the inside of the lockset hole you made in steps five and six.
- Slide the latch mechanism into the hole you just drilled so that it protrudes from the edge of the door. Position the beveled edge of the latch so that it will face toward the doorjam.
- Place the rectangular latch strikeplate over the latch on the edge of the door. Trace the outline of the latch plate, then remove and set aside the latch mechanism.
- Use your chisel to cut along the outline of the latch strikeplate. You should cut no deeper than the thickness of the latch plate, about 1/8 of an inch.
- Place the beveled edge of the chisel against the wood and gently drive out the waste. Reinsert the latch hardware, making sure that the strikeplate lies flush with the edge of the door. Follow the instructions that came with the lockset to finish installation.
- To install the hinges, use the original door to determine the position of the hinges on the new door. One way to do this is to lay the new door atop the old one, then use a ruler to trace horizontal guidelines for the top and bottom of the hinge hardware from old door to the new.
- Place the hinge hardware on the edge of the new door, using the horizontal guidelines you traced in step 11. Trace the vertical edge of the hinge mortice with a pencil.
- Using your chisel, hollow out the area you outlined so that the hinge mortice will lie flush with the edge of the door. You should cut no deeper than the thickness of the mortice.
- Replace the hinge mortice in the hollowed-out area along the door edge. Predrill the holes for the hinge screws, and then attach the hinge plates.
- Reattach the door to the doorframe. You may need assistance to do this.
- Open and close the new door repeatedly to check for a smooth swing, a good catch on the locking mechanism and a good fit.