How do I stop a door catching on the carpet?

Four answers in order of effort — from rising butt hinges that need no cutting, to trimming the leaf — and how much clearance a carpet actually needs.

Difficulty: beginner
Time: 1 hr
Read: 3 min

Short answer

Measure the clearance with the door open over the thickest point of the carpet. If you need less than about 10mm, rising butt hinges lift the door clear without cutting it. More than that and the leaf has to come off and be trimmed.

New carpet, a thicker underlay or a second doormat all raise the floor without anyone thinking about the door. It is one of the few door problems where the door itself has not changed at all.

What you'll need

A tape measure
A pencil
Rising butt hinges, or a saw and a plane

Step by step

Find the worst point.Swing the door slowly over the whole arc and mark where it first touches. Carpet is rarely even, and the pile is thickest where it has been walked on least.
Measure how much you need.Slide a pencil or a stack of card under the closed door and add thickness until it just clears. That figure is what you have to gain.
Check whether the carpet can go instead.A gripper strip fitted too close to the door, or an underlay lapped over a threshold, sometimes adds the exact few millimetres causing the drag.
Try rising butt hinges for up to about 10mm.They lift the door as it opens, so it clears the carpet on the swing and drops back down to seal when closed. They fit the existing recesses in most cases.
Bevel the top edge if you fit them.A rising door tilts as it lifts, so the top corner on the hinge side must be eased with a plane or it will foul the frame head.
Trim the bottom for anything more.Take the door off, mark the cut with the door upside down on trestles, and saw. Trimming is the only honest fix for a large clearance problem.
Respect the door's construction.A hollow-core door has a solid timber lipping at the bottom, typically 25–40mm deep. Cut past it and the door is hollow at the edge and effectively scrap.
Reseal any cut edge.A raw bottom edge takes up moisture from a damp floor and swells. Paint or varnish it before rehanging.
Think about the draught.A large gap under a door is a route for cold air. A brush strip on the door or a threshold seal restores it without stopping the door clearing.

Tips

Cut the door before the carpet is fitted if you can. Everything is easier when the floor is bare and the mess does not matter.
Rising butts are handed. Check whether you need left- or right-hand before ordering, looking at the door from the side it opens towards.
A door that clears an empty room but drags on a rug needs a rug gripper or a different rug, not a smaller door.

Common mistakes

Cutting through the bottom lipping of a hollow-core door — Below the lipping there is only cardboard honeycomb and two skins. The door has nothing to hold a bottom edge together, and no repair is durable — it needs replacing.
Trimming while the door is hung — Cutting in place gives an uneven line, wrecks the carpet and usually the frame too. Ten minutes to take the door off saves the job.

If it doesn't work

Door clears the carpet but now rattles

Cause: Larger gap has reduced the seal — Fix: Fit a brush or drop-down seal to the bottom of the door.

Door drags only near the frame

Cause: Carpet ridged over the gripper — Fix: Re-fit the gripper further back from the door line and re-lay the edge.

Rising butts make the door hard to open

Cause: Top corner fouling the frame head — Fix: Ease the leading top corner with a plane until it swings freely.

Door clears in summer, drags in winter

Cause: Damp carpet or a swelling door bottom — Fix: Seal the bottom edge of the door and check for damp at floor level.

Questions people ask

How much gap should there be under a door over carpet?

Enough to clear the pile at its thickest plus a couple of millimetres — usually 10–15mm above the finished carpet, compared with about 6mm over a hard floor.

Does a large gap under a door matter?

It costs a little heat, but in a room with no other ventilation the undercut is doing a job. Bathrooms and rooms with an extractor need air to get in from somewhere.