Why aluminium doors drag
Aluminium-framed half-glazed doors are the standard fitment on UK commercial entrances — retail shopfronts, office lobbies, restaurants, banks, healthcare reception areas. They are light, strong and visually open. They also work to fine mechanical tolerances. When a single component at the bottom or top of the door wears even by a millimetre or two, the door geometry shifts and the bottom rail starts catching the threshold.
The wear is almost always in one of three places. The bottom pivot (a steel pin in a brass bushing carrying the full vertical load). The top centre (a smaller pivot at the top of the door). Or the floor spring (where fitted — a hydraulic cassette buried in the threshold). All three are wear items with predictable service lives.
The four-stage cascade
Stage 1 — door starts dragging. A faint scrape on the threshold, audible on every open. Repair cost at this stage: £200–£400, one site visit.
Stage 2 — closer over-works. The dragging door arrives at the strike late and off-axis. The closer compensates by pulling harder. Hydraulic seals heat up. Closer service life is shortened. Repair cost when this catches up: £500–£900 on top of the original pivot replacement.
Stage 3 — latch damage. Late-arriving door hits the strike at an angle. Latch tongue bends. Strike plate wears. Latch will not engage on its own. Repair cost: £200–£500 for the latch and strike.
Stage 4 — glazing damage. Slamming door shock-loads the corners of the leaf. Corner welds crack. Glazing rattles in the bead. In the worst cases the corner glass pane cracks under repeated impact. Repair cost: £500–£2,000+ depending on whether the glass needs to be replaced.
A drag caught at Stage 1 is one component, one visit. A drag ignored to Stage 4 is four components, three or four visits.
Diagnosing the drag
Three pieces of evidence are enough for a remote diagnosis in almost every case. First, a photo of the door at rest from inside the building, square-on, showing the line of the threshold and the line of the bottom rail. Second, a photo of the top of the door showing the gap to the head of the frame. Third, a 10-second video of the door closing from full open.
From those three pieces we identify which component has dropped the door (pivot, top centre or floor spring) and whether the closer has started to compensate. The remote diagnosis is wrong in fewer than 5 per cent of cases — the engineer arrives on site with the right parts and the right time allocation in the van.
Repair routes for each cause
If the cause is a worn bottom pivot: 1–2 hours on site, £200–£400 fitted. See transom and bottom pivot repair.
If the cause is a worn top centre: under an hour, £150–£350. See top centre repair or top centre insert replacement where only the bush needs renewing.
If the cause is a worn floor spring: half a day, £500–£1,000. See floor spring repair.
In all three cases the engineer adjusts the closer after the pivot/spring is renewed, so the closer is no longer working against a misaligned door. Skipping that adjustment is a common reason a "repaired" door drags again within months.
See aluminium door repair for the parent service silo and shopfront repair for retail-specific work.
When the drag is from the frame, not the door
Two patterns suggest the drag is structural rather than mechanical. First, a recently-arrived drag on a door that has not had any mechanical work in years — and the door is square within the frame (gap is uniform around the perimeter). The threshold itself may have lifted, often after seasonal moisture cycles or vehicle impact on the surrounding floor.
Second, a drag combined with cracking around the frame fixings or with visible movement of the surrounding shopfront. Vehicle impact is the most common cause; subsidence is the rare one. Either way, the engineer flags the structural issue and the door work is held until the frame has been re-bedded or the structural damage assessed.
Preventing the drag in the first place
A six-monthly maintenance check on an aluminium door catches the early wear in the cheap-fix window almost every time. Closer adjustment, pivot inspection, threshold check, frame-square measurement. Aluminium door service contracts cover this as standard, and we extend the same cover to retail door maintenance contracts for shopfront-heavy estates.
For multi-site retail estates we usually consolidate the maintenance under a single contract with one set of paperwork. See multi-site door maintenance for the scope and pricing.