What APG actually is
APG stands for "all-purpose glass" — sometimes also called all-glass, frameless or patch-fitting doors. The leaf is a single piece of toughened glass (typically 12 mm or 15 mm thick) with no surrounding frame. The hardware connects directly to the glass through cut-outs and bolted patches.
You see APG doors most on premium retail (Kate Spade, Apple, high-end fashion), boutique hotels, restaurant entrances, showroom front-of-house, and corporate office lobbies. They give an open, light, minimal-frame look that aluminium-framed doors can't match.
The downside: they are mechanically demanding. The whole weight of the door, the closing force, and any impact loading all pass through 4–6 small patches bolted through the glass. Wear or damage to any patch propagates fast.
Patch fittings — the load-bearing hardware
At the top of the door, a patch fitting connects the glass to the top centre pivot. At the bottom, another patch connects to the floor spring spindle. On the lock edge, one or two patches house the lock cassette and meet the strike plate. Each patch is a precision-cast metal block bolted through pre-drilled holes in the glass.
The patches themselves are usually steel or brass with a polished or satin finish. They have to fit the glass cut-outs precisely — loose patches stress the glass, tight patches risk cracking it. Once installed, the patches and glass move together as a unit.
Why APG repair is harder than aluminium-framed
On an aluminium-framed door, you can buy off-the-shelf replacement pivots, closers and lock bodies. On an APG door, the patch fittings are usually specific to the manufacturer of the door — Dorma, Geze, Briton, Adams Rite, Sun Valley, Forster, plus dozens of smaller marques. Many of those systems are no longer in production, especially anything fitted before 2005.
When a patch fitting fails on a discontinued system, the engineer's options are: (1) find a refurbished original part through a specialist supplier, (2) cross-reference to a compatible current part, (3) source a bespoke replica machined to the original spec, or (4) recommend the door be re-glazed with a current-spec set.
A well-networked engineer can almost always find option 1 or 2 — which keeps the door in service for £500–£1,500 instead of the £3,000+ a full replacement costs. This is where the expertise actually lives.
The three most common APG door faults
1. Floor spring failure. The floor spring under an APG door is doing more work than under an aluminium-framed door — it carries the full closing weight of a heavy glass leaf with no frame to share load. Floor springs on APG doors typically need replacement every 8–12 years. Symptoms: slam, stop-short, or fluid weep from the threshold (see [[commercial-floor-spring-explained]]).
2. Lock cassette failure. The lock body sits in a patch fitting on the lock edge. Wear in the latch, hookbolt or cylinder produces a door that won't lock or won't open. Repair: lock cassette replacement, often the original patch fitting can be retained.
3. Top pivot wear. The top patch connects to the head of the frame through a top centre pivot. As the pivot wears the top of the door drifts out of square. Repair: top centre replacement, usually 1–2 hours on site.
What replacement looks like vs repair
Full APG door replacement is around £3,000–£6,000+ for a single doorset, depending on size, brand and patch fittings spec. Single-component repair (floor spring, top centre, lock cassette, individual patch fitting) is £500–£1,500. The vast majority of "broken" APG doors we see are repairable.
Where the glass itself is damaged (chipped corner, cracked edge, scratched panel) the calculus changes — the toughened pane has to be replaced and once you are paying for a new pane, full doorset replacement may be sensible if the patches are also at end of life. An engineer's site survey settles this in 30 minutes.