How do I plane a door edge properly?

This is a technique guide, not a diagnosis. Before planing anything, be sure the door genuinely is too big: a door that has dropped on worn hinge screws, or one that only catches in damp weather, will be gappy for ever if you plane it. Once you are sure, the job is straightforward and the details below are what separate a neat result from a visibly tapered door.

Safety

What you'll need

• Sharp plane — block plane for small amounts, jack for more
• Screwdriver and something to support the door
• Pencil, compass or a washer
• Try square
• Primer or paint and a brush
• Electric planer (optional)

Step by step

1. Confirm it needs planing at all.Tighten every hinge screw, plug and refit any that spin, and check whether the door only catches in damp weather. Fixing the hinges is reversible; planing is not.
2. Find exactly where it binds and how much.Close the door slowly and look for the rub mark, or run a slip of paper round the gap and note where it grips. Mark the tight area on the door with pencil while it is still hung.
3. Choose the edge to plane.The hinge side, if you can, because the hinge rebates hide small irregularities and the edge is barely visible when the door is shut. Take it off the top if the door catches on the head. Only plane the lock side if the amount is small and the latch and strike can still line up — a lock side taken down more than a few millimetres means moving the latch and the strike plate.
4. Take the door off and support it properly.Unscrew the hinge leaves from the frame rather than from the door where possible, so the hinge positions on the door are undisturbed. Stand the door on edge in a purpose-made door stand, or clamp it between two blocks against a wall or in a vice. It must not move.
5. Mark the line to plane to.Set a compass or hold a washer with a pencil in it, and run it along the frame side and onto the door edge to transfer the exact gap. That gives a line that follows the frame, which is much better than a straight line measured from a tape, because frames are rarely straight.
6. Check the required bevel.A door needs a slight lean on the leading edge — the lock side is planed very slightly back so the closing edge does not bind on the frame as it swings. A couple of degrees, off the inside face, is standard, and it is the difference between a door that closes and one that catches at the last moment.
7. Plane in long passes along the whole edge.Start each stroke at one end and run right through to the other. Short strokes in the middle produce a hollow, and the door then binds at the ends. Keep the plane's sole flat and let the tool do the work.
8. Check for square constantly.A try square across the edge, in several places along the length. It is very easy to plane a rounded or a leaning edge without noticing, and the result is a door that only touches the frame at one point.
9. Take a little, offer it up, repeat.Rehang or offer the door and check the fit after every few passes. Removing a millimetre too much is impossible to undo without a lipping.
10. Ease the arrises and seal the edge the same day.Take the sharp corners off with fine abrasive, then prime and paint the planed edge before the door is rehung. Bare timber takes up moisture, swells, and recreates the problem you have just fixed — this is the step most often skipped.

Tips

• Plane inwards from each end towards the middle to avoid splitting the corners, especially on the top and bottom edges where you are cutting end grain on a stile.
• For more than a few millimetres, an electric planer removes the bulk quickly. Finish the last pass with a hand plane, because a power planer leaves scalloped ridges and snipes at the ends.
• On a hollow-core internal door, there is only a narrow solid lipping around the edge. Plane more than that away and you open the hollow core, which then needs a new lipping glued in.
• Take a photo of the hinge positions and any packing before you take the door off.
• A fire door must not be planed beyond the manufacturer's stated tolerance, and the gap around it is part of its certification. If a fire door does not fit, that is a job for someone who can confirm it still complies.

Common mistakes

• Planing the lock side by more than a few millimetres — The latch no longer reaches the strike plate, and both have to be moved — far more work than planing the hinge side would have been.
• Leaving the planed edge bare — Bare timber absorbs moisture and swells back, and the door sticks again in the first damp spell.
• Planing a door that only sticks in winter — It will be visibly gappy in summer. Seasonal movement is normal and usually needs no permanent correction.
• Planing to a straight line measured with a tape — Frames are not straight. Scribe the line from the frame itself with a compass and the door will follow it.

Questions people ask