How do I hang a door in a frame that is out of square?

In any house more than a few decades old, the opening will not be square, and hanging a rectangular door in it is a matter of deciding what to compromise. The important judgement is whether the frame is merely out of square, which the door can absorb, or actually out of plumb, which it cannot.

What you'll need

• A long spirit level, ideally as tall as the opening
• A tape, pencil and a straightedge
• A hand plane and a sharp block plane
• Wedges or packers
• A pair of hinge-thickness offcuts as gauges (optional)

Step by step

1. Survey the opening before touching the door.Width at top, middle and bottom. Height at both sides and the centre. Both diagonals. Plumb on both lining legs, in two directions — across the opening and through the wall thickness. Write every figure down.
2. Separate 'out of square' from 'out of plumb'.Out of square means the opening is a parallelogram or a trapezium but the legs are vertical. The door can be scribed to that and it will behave. Out of plumb means a leg leans, and a door hung on a leaning hinge leg will swing open or shut on its own no matter how well it is fitted.
3. Correct the lining if it is out of plumb.Take the architrave off the hinge side, slacken or remove the fixings, pack behind the lining until the hinge leg is plumb in both directions, and refix. Getting the hinge leg plumb is worth real effort; the closing leg matters much less.
4. Decide where the taper will go.If the opening is out of square, one edge of the door will have a tapered gap. Put it where it shows least: the top usually, or the closing edge if the taper is small. Never taper the hinge edge, because it changes the hinge geometry.
5. Scribe the width.Hold or wedge the door in the opening, packed to the correct bottom clearance, and set a compass or a block-and-pencil gauge to the largest gap. Run it down the closing edge to transfer the lining's shape onto the door.
6. Plane to the scribed line with a bevel.Take the closing edge down to the line, planing a slight bevel — a couple of degrees — so the leading arris clears the lining as the door swings. Without that bevel a wide door binds on the closing edge as it shuts.
7. Fit the hinge edge straight, not scribed.The hinge edge stays straight and the hinges are packed to correct any lining discrepancy. Scribing the hinge edge to a wavy lining puts the hinge knuckles out of line with each other, which binds the door.
8. Line the hinge knuckles up.All hinge knuckles must sit on one straight vertical line. Check with a straightedge or a taut string down the lining before cutting the recesses. This is what makes a door swing sweetly in a frame that is not perfect.
9. Hang it and read the gap.Hang on the top hinge first with one screw per hinge and check. Adjust by packing behind a hinge leaf to move the door away from the hinge side, or by deepening a recess to move it towards. Only when the gap is right does every screw go in.
10. Scribe the bottom last.With the door hanging, mark the floor line and the clearance the floor covering needs. If the floor slopes, the bottom gets scribed to it. Take the door off to cut the bottom rather than trying to plane it in place.
11. Ease the top last of all.The top is where a tapered gap is least visible. Plane it to a consistent clearance rather than a consistent measurement from the head.
12. Accept the compromise you chose.In an out-of-square opening, a perfectly parallel gap on all four edges is not achievable without rebuilding the lining. A consistent, small, deliberate taper in one place looks far better than four edges each slightly wrong.

Common mistakes

• Hanging the door before plumbing the lining — A hinge leg that leans makes the door swing on its own, and no amount of planing corrects it. Half an hour with a level and some packers at the start saves the whole job.
• Scribing the hinge edge — It throws the hinge knuckles out of alignment and the door binds. The hinge edge stays straight; discrepancies are packed out behind the hinge leaves.
• Planing the closing edge square — A door pivots into the opening, so a square closing edge catches on the lining before it is shut. A slight bevel is standard practice, not a bodge.

Questions people ask