How to fit a door bar (threshold strip)

Video by Proper DIY. This walk-through is inspired by the video "How to Fit a Door Bar (Threshold Strip) | Carpet-to-Flooring Transition Made Easy" from Proper DIY, a solid UK channel that covers flooring and home improvement in clear, practical steps. The section on getting the carpet tucked neatly under the gripper edge of the bar is particularly useful if you are working with a carpet-to-hard-floor transition.

1. Choose the right type of threshold strip

There are several profiles available and picking the wrong one is the most common mistake. A T-bar (or T-profile) is used where two hard floors of similar height meet — laminate to laminate or LVT to tile, for instance. A reducer strip is used where one floor is noticeably higher than the other, tapering from the higher surface down to the lower. A carpet-to-hard-floor bar has a gripper edge on one side that tucks into the carpet pile.

Most door bars in UK sheds are sold in a standard length of 90 cm or 93 cm, which covers the vast majority of internal doorways. Check the width of your doorway before you buy — it sounds obvious but it is easy to assume. Colour-matching matters too: a silver bar in a hallway with oak laminate will look out of place. Most manufacturers offer silver, gold, and a range of wood-effect finishes.

2. Measure and mark the fixing position

Close the door and note exactly where the door sits on the floor — the strip should sit under the door when closed, not in front of it. Mark a pencil line across the floor at the centre of the doorway. This is where the fixing track (the metal channel that most door bars clip into) will be positioned.

Measure the width of the opening between the door linings at floor level. Mark the length on the track and on the decorative bar. Cut both to the same length. Most tracks cut easily with a hacksaw; the decorative cover bar is usually aluminium and cuts just as cleanly. Deburr the cut ends with a file or fine sandpaper — it will save you nicked fingers later.

3. Fix the track to the floor

Hold the track in position along your pencil line and mark through the pre-drilled holes with a sharp pencil or bradawl. Most tracks have three or four holes along their length. Drill pilot holes — a 5 mm bit works for most solid floors. On concrete or screed, you will need a hammer drill and masonry bit, plus wall plugs before the screws go in.

On timber floorboards or chipboard, a pilot hole prevents the wood splitting. Screw the track down firmly but do not overtighten on chipboard — the screws strip out easily. If you are fixing to underfloor heating screed, check the depth of the screed first and use short screws. Mind you, if in doubt, a good contact adhesive under the track will do most of the work on solid floors.

4. Deal with the carpet edge (carpet-to-hard-floor bars)

If one side of the doorway is carpeted, the carpet edge needs to be tucked cleanly into the gripper channel on that side of the bar. Lift the loose carpet edge, position the track so the gripper teeth face the carpet side, and screw down. Then tuck the carpet pile under and into the gripper channel using a bolster chisel or the flat end of a screwdriver — push firmly until the pile is held. It should not pull free under normal foot traffic.

Trim off any excess carpet with a sharp Stanley knife before tucking. A frayed or ragged edge will show under the bar and it will bother you every time you walk past. It depends on the carpet pile, but a clean cut makes the job look considerably better.

5. Fit the decorative cover bar

Once the track is fixed and any carpet is tucked, the decorative bar simply presses or clips into place over the top. Most bars have a lip that hooks into one side of the track, then the other side presses down with a firm push. You should hear or feel a click as it seats.

If the bar is stiff to clip, check there is no debris in the track channel. A bit of grit or a curl of carpet fibre can stop it seating flush. On some older or cheaper systems the bar is screwed down through the face rather than clipped — if that is what you have, countersink the screw heads so they sit flush and use screws that match the bar finish.

6. Check the door still clears the bar

Close the door slowly and watch the clearance between the bottom of the door and the top of the threshold strip. There should be roughly 3–5 mm of clearance — enough so the door does not drag on the bar but not so much that you get a draughty gap when it is shut.

If the door catches, the bar may be sitting too high because the track has been raised by debris or an uneven floor. Check the floor is clear under the track before re-fixing. If the door was already close to the floor before you started, you may need to trim the bottom of the door slightly — a job for another day, but worth noting now rather than discovering the problem next winter when the door swells.

When to call a handyman

Call Richard if the floor levels are very different and you are not sure which profile to use, if the concrete subfloor is too hard to drill without proper kit, or if you are fitting strips at the same time as new flooring is going down and you want the whole job done together. Sometimes it just makes sense to have everything finished in one visit rather than coming back to it. Get in touch and Richard can advise on the right strip for your floor type.