A door blank, also called a slab door, arrives without hinges, lockset, or finish. Buying blanks opens up design choices that pre-hung doors do not offer: more stock in the lumberyard, the option to match an existing interior style, and the chance to reuse a vintage door found at a salvage yard. The trade-off is that the homeowner cuts the hinge recesses themselves. The process of sinking hinges flush into the door edge is called mortising, and it decides whether the door opens and closes properly. The same layout skill pays off when you cut a brick wall to install a new door opening, because both jobs come down to accurate marking and clean, square cuts.
The project suits an intermediate DIYer with a chisel, a mallet, and a few hours. The overview numbers set expectations: working time around 15 minutes, total project time 15 to 30 minutes for two hinges, a cost of $10 to $20 in hardware, and a yield of one door blank fitted with two hinges.
Understand Mortising and Door Swing First
A hinge must be recessed into the door so the top surface of the leaf sits flush with the door edge. Mortising gives a tighter fit and more strength than surface mounting, and it lets the hinge pin line up with the gap between door and jamb. A flush hinge also lets the door close fully into the stop without binding. The same layout discipline applies to other openings; installing a sliding glass door step by step starts with the same careful marking and squaring of the rough opening.
Swing Direction and Local Codes
Hinge placement controls the direction of the door swing. In some cases, the door must swing in the direction of egress, such as a bedroom door that opens toward the hallway or an exterior door that opens outward. Check with the building department for door swing requirements in your area before cutting anything.
Handing a Door
Stand on the side the door swings toward. If the hinges are on your left, the door is left-handed; on your right, right-handed. Order or cut the hinge pockets accordingly, and keep the hinge pins on the interior side of an exterior door so they cannot be pulled from outside.
Tools and Materials for the Job
Most of the tools live in a basic toolbox already. A hinge mortising jig is optional but worth the money if you plan more than one door; a router with a pattern bit turns the job into a repeatable operation. For a single door, a sharp chisel, mallet, utility knife, and pencil are enough. Fine Homebuilding shows how to install hinges easily without a door buck, a jig that clamps the door upright while the mortise cuts are made.
- Chisel set with 1/2-inch and 3/4-inch blades to match common hinge leaves
- Mallet, utility knife, combination square, and pencil
- Drill with pilot bit and hinge screws, typically 3/4-inch for the door and 1-inch for the jamb
- Safety glasses; chisels are sharp, so cut away from your body
Plan on $10 to $20 for two quality hinges and screws. Standard residential hinges run 3.5 inches for interior doors; exterior and heavier doors use 4-inch or 5-inch hinges with ball bearings. Most interior doors use plain butt hinges with removable pins. Ball-bearing hinges last longer on heavy doors because the bearings carry the load instead of the pin rubbing the knuckle.
Choosing the Right Hinge for the Door
Match the hinge to the door weight, not the look. A hollow-core interior door weighing 30 to 40 pounds works fine with two 3.5-inch hinges. A solid-core door at 80 to 100 pounds needs three hinges, and the jamb screws should bite a full inch into the frame.
Screw Selection
Use the screws that come with the hinge for the door leaf, but upgrade the jamb side with 1-inch or longer screws. Longer jamb screws reach past the casing into the wall stud, which keeps the hinge from pulling loose under heavy use.
Mark and Cut the Mortise, Step by Step
Work with the door on sawhorses, face up or edge up. Lay out both hinge positions before picking up the chisel, measuring from the top and bottom edges of the door rather than the cut ends, because blanks can vary by an eighth of an inch. A combination square keeps the hinge line perpendicular to the door edge. Once the door is prepped, the rest of the installation mirrors the sequence you would follow installing a new storm door in an old opening, where accurate fit against an existing frame is everything.
- Mark hinge locations. Standard placement is 7 inches down from the top edge and 11 inches up from the bottom for a two-hinge door, or 7 inches from the top, 11 inches from the bottom, and centered for three hinges.
- Score the outline. Hold the hinge leaf in place, trace it with a sharp pencil, then cut the outline with a utility knife to about 1/16-inch depth.
- Set the depth. The mortise depth equals the leaf thickness, about 1/8 inch for standard residential hinges.
- Chisel out the waste. Work from the scored lines inward with the bevel down, cutting across the grain first and then along it. Remove thin slices, 1/16 to 1/8 inch at a time.
- Test the fit. Set the hinge in the pocket; the leaf should sit flush with the door edge and show no rocking.
Router Method for Repeatability
A router with a pattern bit and a hinge template cuts the same pocket in about a minute. Set the bit depth to the leaf thickness, clamp the template, and run the router clockwise around the template opening. The router method pays for itself when hanging several doors in one renovation.
Attach the Hinges and Hang the Door
With the pockets cut, screw the hinge leaves to the door with the supplied screws, then position the door in the opening. Shim the bottom edge so the door sits about 1/8 inch above the finished floor. Close the door against the stop, mark the hinge positions on the jamb, and cut matching mortises there. Screw the leaves home and test the swing. If the door binds, a hinge screw or pin adjustment fixes most issues, and a door that develops noise later is easy to correct with the effective DIY fixes for noisy hinges.
Getting the Gaps Right
- Hinge side: 1/8-inch gap between door and jamb
- Latch side: 1/8-inch gap
- Top edge: 1/8-inch gap
- Bottom: 1/2 to 3/4 inch over carpet, about 3/8 inch over hard flooring
The hinge pin should sit parallel to the door edge after the door is hung. Sight down the edge of the door; if the door tips toward the jamb at the top, the top hinge pocket is too deep, and if it pulls away, the bottom pocket is too shallow.
Shimming and Temporary Screws
Screw the jamb leaves in place with one screw each, close the door, and check the gaps before driving the rest. This dry fit catches alignment problems while the screws are easy to remove. After the door hangs square, drive all the screws and add the strike plate.
Adjustments, Clearances, and Finishing Touches
Most alignment problems trace to one of three places: hinge screws not fully seated, a mortise cut too deep, or a door that swells with humidity. Tighten or shim the screws first, then check the leaf for flush fit. Door hardware needs the same patient fit-up as the rest of the entry assembly, which is why a finished opening gets the same care as installing an awning over an entry door, where every gap shows.
Common Fit Problems and Fixes
| Problem | Cause | Fix |
|---|---|---|
| Door binds at the top hinge | Top mortise cut too deep | Add a thin cardboard or veneer shim behind the top leaf |
| Door swings shut on its own | Hinges not plumb | Adjust the hinge pin or re-seat the jamb leaf |
| Gap wider at the top than the bottom | Uneven mortise depth | Re-cut the shallower pocket and test again |
| Squeak after months of use | Dry hinge pin | Lubricate with a few drops of oil or paste wax |
Protecting the Finish
Seal the raw mortise wood before installing the hinge so moisture cannot swell the pocket. Prime and paint or apply a clear finish to the cut edges, then touch up the surrounding area after the hardware is in place.
Plan the Hardware Before You Cut
The hinge count and hinge size should be decided before the first knife cut. A lightweight interior door works with two hinges; a solid-core or exterior door needs three; a wide or heavy door may need four. Match the leaf size to the door thickness, and confirm the swing direction with the building department before buying anything. The rules for choosing the right number of hinges for any door apply whether you are hanging a slab, a storm door, or a pantry door, so review them before you purchase hardware.
Install the hinges once, squarely, and the door will swing smoothly for decades. The 15 minutes of layout saves hours of rework, and the same careful approach carries through every other opening in the house.