How to Replace an Interior Door

Swapping a door slab into an existing frame is one of the most satisfying weekend upgrades — and the trick is mortising the hinges right.

If your existing jamb is square and in good shape, replacing just the slab is much faster than a pre-hung door. Measure the existing slab — width, height, thickness (usually 1-3/8"), and the hinge layout. Bring measurements when you order; many home centers will pre-machine the new slab for hinges and a knob for $25.

If you cut the hinges yourself, transfer hinge locations from the old door to the new with a sharp pencil and a combination square. Use a router with a hinge template, or score the outline with a sharp utility knife and chisel out the mortise. Depth should equal the hinge leaf thickness exactly — too deep and the door binds, too shallow and it won't close.

Hang the door on the top hinge first with one screw, check the swing, then add the bottom hinge. Adjust shimming as needed until the gap (called the 'reveal') is even all the way around — about the thickness of a nickel on the latch side and 1/8" at the top.

Drill the knob and latch hole last, using the existing jamb strike position as a reference. A door installation kit ($25) makes hole placement foolproof.