How do I fix a threshold strip that keeps coming loose?

A threshold takes more foot traffic than any other part of the floor and it is usually fixed with the least. It comes loose because the fixing was into the wrong thing.

What you'll need

• The correct threshold profile
• A drill and masonry or wood bit
• Screws and plugs, or the strip's own base track
• Grab adhesive
• A hacksaw and a file

Step by step

1. Take it up and look underneath.How it was fixed tells you why it failed. Plugs into the gap, screws into the floor, adhesive only, or a base track are the four you will find.
2. Check what floors it joins.Equal heights take a T-bar; a small step takes a ramp or reducer; a bigger step takes a lipped cover strip; an edge that joins nothing takes an end profile.
3. Establish whether either floor is floating.This decides everything. A floating laminate or LVT click floor must not be screwed through, because that pins the boards and stops the whole floor moving.
4. Fix into the subfloor through the gap.The correct method. The strip's stem or its base track drops into the expansion gap between the two floors and is fixed to the subfloor beneath, so neither floor is pinned.
5. Use a base track where you can.Many thresholds come with an aluminium base track that screws or glues to the subfloor, with the visible strip clipping into it. It is far more durable than fixing through the strip.
6. Drill and plug into concrete properly.The correct bit size, blow the dust out, and a plug that fills the hole. Most failures in concrete are a hole drilled too large or full of dust.
7. Do not rely on adhesive alone in a doorway.Grab adhesive under a strip in a busy doorway takes constant flexing and peel. It is acceptable to supplement a mechanical fixing, not to replace one.
8. Check the height.A strip that stands proud is a trip hazard and gets kicked loose repeatedly. It should sit as close to flush as the two floor levels allow.
9. Cut it accurately.A hacksaw with a fine blade, then file the cut end. A ragged end catches feet and vacuum cleaners.
10. Scribe to the door frame.The strip should run right up to the architrave on both sides, cut around the frame rather than stopping short of it.
11. Consider where the joint sits.Conventionally the threshold sits below the closed door, so each room sees only its own floor. It also puts the strip out of the main traffic line.

Tips

• Buy the strip with its own base track rather than a solid one with countersunk screw holes. It looks better and holds far longer.
• In a doorway with a concrete subfloor, one plug every 200mm is not excessive. Doorways take an enormous amount of traffic.
• If a strip has come loose more than once, the fixing method is wrong. Do not simply put longer screws in the same holes.

Common mistakes

• Screwing the threshold through a floating floor — It pins the boards at that point. The floor then expands against a fixed anchor, which produces peaking, opened joints, or a snapped locking profile somewhere else in the room — often far from the doorway.
• Fixing only with adhesive in a busy doorway — Adhesive resists shear reasonably and peel very poorly. Every foot that lands on the edge of the strip peels it a little further, and it lifts within months.

If it doesn't work

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