Glass Door Hardware 2026: Thickness Ranges, Cut-Out Dimensions, and the One Step That Cannot Be Undone

There is one sentence in this trade that costs more money than any other, and it is said by somebody standing in front of a finished glass door with a fitting in their hand: "can we just drill it?"

No. And the reason is worth understanding properly, because it governs the entire order sequence for a glass door and it is the only hardware category where a mistake destroys the component rather than delaying it.

WHY TOUGHENED GLASS CANNOT BE CUT

Toughened — or tempered — glass is made by heating annealed glass and cooling the surfaces rapidly. The surfaces go into compression and the core into tension, and that locked-in stress balance is what makes the pane strong and what makes it break into small blunt fragments instead of shards.

Cutting, drilling or grinding it releases that balance. The pane does not chip; it disintegrates, immediately and completely, across its whole area.

So every hole, notch, cut-out and edge treatment has to exist in the glass before it goes into the furnace. After toughening, the pane is finished. A 2,400mm glass leaf that needs one more 20mm hole is a new leaf.

This is why glass door hardware has to be selected before the glass is ordered, not after the glass arrives — the opposite of the sequence most people are used to with timber and metal doors.

THE THICKNESS RANGES WE ACTUALLY PUBLISH

Different fittings accept different glass thicknesses, and the ranges across our own catalogue are these.

A fitting quoted for a range achieves it with gaskets or packers, not by clamping harder. That matters, because the packers are part of the supplied set. A fitting installed on 8mm glass without the packers for 8mm is a fitting that will work loose, and the packers are the item most likely to be left in the box.

THE GLASS GAP

Some of our fittings publish a glass gap dimension — 7mm and 7.5mm across the catalogue. This is the clear opening between the clamping faces before the gasket goes in, and it is the number that determines which glass thicknesses the fitting can actually take.

It is worth reading alongside the thickness range rather than instead of it. A fitting with a 7.5mm gap taking 8mm glass is compressing a gasket, which is the intended arrangement. A fitting whose gap is larger than the glass plus its gaskets is a fitting that has nothing to grip.

THE CORNER RADIUS

A cut-out in glass is made with a rotating tool, which cannot produce a sharp internal corner, and a sharp internal corner in glass would be a stress concentration and a crack waiting to start.

So cut-outs carry a corner radius, and it has to be stated. The R6 on our 12mm model is a 6mm radius. A glass processor given a cut-out with no radius specified will use their own standard, which may not match the fitting, and the mismatch shows as a gap at each corner on a component where every edge is visible.

TOUGHENED, LAMINATED, OR BOTH

Toughened glass breaks into small blunt fragments and falls out of the opening. Laminated glass has an interlayer that holds the fragments in place when it breaks.

Which is required is a building decision — overhead glazing, balustrades, and locations where a falling pane would be dangerous typically call for laminated or laminated-toughened rather than toughened alone. That decision affects the hardware, because a laminated pane at a given nominal thickness includes an interlayer, and the fitting has to accept the actual assembled thickness rather than the glass alone.

State the full build-up on the order — for example "10mm toughened" or "11.5mm laminated toughened, 5+5 with 1.5mm interlayer" — rather than a nominal figure, because the fitting grips what is physically there.

WHAT HAS TO BE ON THE GLASS SHOP DRAWING

This is the document that makes the whole thing work, and it has to be agreed between the hardware supplier and the glass processor before either commits.

The glass build-up: thickness, toughened or laminated, and the interlayer if any.

Every hole and cut-out, dimensioned from two datum edges — not from each other, because errors accumulate.

The corner radius for each cut-out.

The edge treatment: polished, ground, arrised.

The handing and which face is which, because a cut-out that is symmetrical in plan may not be symmetrical in the fitting.

Clearances at head, floor and jamb, and at the meeting stile on a pair.

The hardware model numbers the drawing was prepared against, so that a later substitution is visibly a change to the drawing rather than a quiet swap.

THE ORDER SEQUENCE THAT WORKS

Select the hardware. Obtain its dimensioned drawings or templates. Give those to the glass processor. Have the processor produce a shop drawing. Check the shop drawing against the hardware drawings. Approve it in writing. Then cut and toughen the glass, then order.

The sequence people actually follow is: order the glass, then choose the hardware, then discover the cut-outs are wrong. The difference in cost between the two sequences is the cost of the glass.

WHAT WE PUBLISH

Our glass door fitting pages carry the glass thickness range, the glass gap where the model publishes one, and cut-out dimensions including the corner radius where a drawing gives them — with imperial equivalents on the English pages.

Where a model does not publish a cut-out dimension, the row is absent and the drawing is the authority. This is the product category where that discipline matters most: a plausible dimension in a specification table for a timber door costs a cover plate, and the same plausible dimension for a glass door costs the leaf.