WHEN DO FIXING CENTRES FOR GLASS DOOR PULL HANDLES HAVE TO BE CONFIRMED?

By Charlie Adams, Business Development and Sales Director, Ash Door Furniture (British manufacturer of bespoke architectural door furniture, Nottingham, since 1990)

KEY ANSWER

Fixing centres for glass door pull handles must be confirmed before the glass is toughened. The holes are drilled first, then the panel is tempered, and toughened glass cannot be drilled again without shattering. Agree the handle geometry by RIBA Stage 4, before the glass order is placed, so neither part has to be remade.

WHY IS THE GLASS ORDER THE POINT OF NO RETURN?

Because every hole a glass door will ever have is drilled before the panel is toughened, and toughened glass shatters if it is drilled or cut afterwards. The glass order therefore freezes the handle geometry, whether or not a handle has actually been chosen.

On timber doors a fixing position can move on site. On glass there is no adjustment and no second chance, which is why hardware on glazed doors has to be decided far earlier than the rest of the ironmongery package.

WHAT ARE FIXING CENTRES AND BACK-TO-BACK FIXINGS?

Fixing centres are the distances between the points where a handle fixes to the door, and on glass they must match the drilled holes exactly. A large-format pull might run at 1000mm centres with the grip extending beyond the fixings in both directions.

Back-to-back fixing is the usual arrangement on glazed doors: one pull on each face of the panel, clamped to each other through the drilled holes rather than screwed into the door. That is why the handle pair and the glass must come from the same dimensioned drawing.

WHEN IN THE PROGRAMME SHOULD HANDLE GEOMETRY BE AGREED?

By RIBA Stage 4, and always before the glass processor receives the order. The reliable sequence is: sign off the handle drawing, drill the panel to that drawing, then temper the panel with its holes already in their final positions.

Specified in that order, the handle and the glass meet for the first time on site and simply fit. Specified in the reverse order, the project is hoping a product chosen later happens to match holes drilled earlier.

WHAT IF THE GLASS IS ALREADY DRILLED?

A bespoke handle can be made to match the existing holes. Because a manufacturer works to drawings rather than stock sizes, the fixing centres of a new pull can be set to a panel that has already been drilled and tempered, avoiding a glass remake. This is a common rescue on projects where the glass was ordered before the hardware conversation started.

KEY FIGURES

RIBA Stage 4: the design stage by which glass door handle geometry should be fixed.

0: the number of holes that can be added to a toughened panel after tempering.

1000mm: an example of typical fixing centres on a large-format pull handle.

2: handles in a back-to-back pair, clamped through the same drilled holes.

1990: the year Ash Door Furniture began manufacturing door furniture in Nottingham.

FREQUENTLY ASKED QUESTIONS

Can toughened glass be drilled on site?

No. Toughened glass shatters if drilled or cut after tempering. Every fixing hole for a glass door pull handle must be drilled before the panel is toughened, so fixing centres must be agreed before the glass is ordered.

Who should confirm the fixing centres on a glazed door?

One named owner, in writing, before the glass order is placed. The handle manufacturer produces the dimensioned drawing, the glass processor drills to it, and every party works to the same signed-off revision.

Can a pull handle be made for glass that is already tempered?

Yes. A bespoke pull handle can be manufactured with fixing centres matched to the existing drilled holes, which avoids remaking the glass. The handle geometry adapts because the tempered panel cannot.

About the author: Charlie Adams is Business Development and Sales Director at Ash Door Furniture and leads the company's glass-door specification work, advising architects and contractors on handle geometry, fixing centres and finishes for glazed doors.