Why aluminium shopfront doors are different
Aluminium-framed half-glazed doors dominate UK shopfronts because they balance weight, strength and visibility well. They are not delicate, but they are precision-engineered — every pivot, closer and lock works within tolerances measured in millimetres. Small amounts of wear push parts out of tolerance and the symptoms appear quickly once they do.
The advantage is that early-stage faults are visible and audible. The disadvantage is that the symptoms are easy to live with for weeks before the door actually fails — by which time the simple repair has cascaded into a multi-part job.
Sign 1: drag at the threshold
You see a scrape mark on the floor under the bottom rail. You hear a soft scratch when the door opens. The door has lost height — usually because the bottom pivot has worn down.
At this stage the repair is a pivot replacement, typically 1–2 hours and £200–£400. Left alone, the dragging accelerates wear on the closer (which is now working against a misaligned door) and the latch (which is no longer meeting the strike cleanly).
Sign 2: slow self-close or stopping short
The door no longer closes fully under its own weight. It slows in the last 10 degrees, stops a few millimetres short, or needs a push to latch. This is almost always the closer — either the hydraulic seals are tired (closer needs replacement) or the closing-speed valve has been wound too far (a five-minute adjustment fix).
Try this first: open the door fully and let it go from rest. A correctly-tuned closer brings it home in 4–6 seconds with a positive latch click. If it stops short, the latch-speed valve needs opening up. If it slams home in 2 seconds, the closing-speed valve needs winding back.
Sign 3: slamming
The opposite of stop-short. The door comes home with a bang you can feel through the frame. Closer fault, almost certainly: the spring is past its service life, the seals are starting to leak, or someone has set the closing speed too fast trying to compensate for poor latching.
Slamming is more serious than it sounds. Every slam shock-loads the bottom pivot and stresses the glazing. A door that slams for six months will need a pivot replacement on top of the closer; a door that slams for a year may also need glazing repair.
Sign 4: fluid on the floor or top of door
A dark spot of oil on the floor under the transom (the metal bar at the top of the frame), or a film of fluid on the top of the door, means the transom closer’s hydraulic seals have failed. There is no field-repair for a leaking closer — the body cannot be re-filled or re-sealed in situ. Replacement is the only fix.
A transom closer replacement is the biggest of the standard aluminium-door jobs — typically £500–£900 and a half day on site. We schedule out-of-hours where the door must stay in service during business hours.
Sign 5: top of door drifting from the frame
Stand square to the door and look at the gap between the top of the door and the head of the frame. On a sound door the gap is uniform, 2–4 mm. On a door with a worn top centre, the gap is bigger on the latch side than the hinge side, and you can rock the top of the door in and out of the frame with light pressure.
Top centre replacement is a one-hour job — but if you can already see daylight through the gap, the door has been running on it too long and the wear will have progressed into the closer.
Sign 6: latch refuses to engage
You can pull the door home with the handle but it will not latch on its own. Two common causes. First, the strike plate has moved or worn — bend the latch tongue, check the strike alignment, swap the plate if necessary. Second, the closer is set too soft and is not bringing the door home with enough force to extend the hookbolt — adjust the latch-speed valve.
A more serious cause: the lock body itself has failed. A hookbolt that no longer extends fully needs a new lock case. Half a day on site, typically £300–£600 depending on the brand.
What to send for a same-day quote
A clear photograph of the door at rest from the inside, a second photo of the closer (look up at the transom or above the door), and a 10-second video of the door closing from full open. That is enough for a same-day quote and dispatch in the large majority of cases. Add a description of when the symptom started and any recent events (new tenant, refurb work, vehicle impact, vandalism) — context speeds the diagnosis up.