GLASS & DETAIL
Glass thickness, explained.
Understand pane thickness, insulating glass units and safety glass before specifying your steel windows or doors.
4 minute read
Choose the system and the purpose of the glass first. A thicker unit is not automatically a better or compatible specification.
Three dimensions that mean different things
Profile depth measures the frame from front to back. Pane thickness measures an individual piece of glass. Overall glazing thickness measures the complete infill held by the frame: a single pane, laminated pane or sealed insulating glass unit.
For example, a 4 / 16 / 4 insulating unit contains two 4 mm panes and a 16 mm cavity: 24 mm overall. A 4 / 16 / 4 / 16 / 4 unit totals 44 mm. These examples explain the arithmetic; they are not an offered glass specification.
The frame sets the glazing envelope
The maximum glazing figure is a limit for the stated product configuration. It does not mean every thickness below it is available. Beads, gaskets, glass weight, panel size and hardware still need to work together.
Our Unico and Unico XS window sashes have different glazing capacities from their matching door systems. Loft and Loft Folding use 6 or 8 mm single glazing. We confirm the Norm Slide and Norm Pivot glass specification for your project. Use our technical comparison to check the exact product.
Safety treatment is a separate choice
Toughened glass is treated to improve its strength and breakage behaviour. Laminated glass uses an interlayer to hold broken fragments together. The right construction depends on the location and the required impact, retention or security performance.
Doors, low-level glazing and some adjacent panels require particular consideration. Tell us about floor level, any drop beyond the glass and whether it forms a barrier. A choice labelled “safety glass” does not by itself confirm suitability for guarding, a fire door or a security-rated assembly.
- Ask for the exact glass build-up and applicable classification in the quotation.
- Record acoustic, solar-control, privacy or retention requirements when you plan the opening.
- For fire protection, specify and verify the complete tested assembly, including the frame and fittings.
What to enter in the planner
Enter your preferred overall glazing thickness only if you know it. Otherwise choose advice required and describe the result you need: a quieter bedroom, less solar gain, privacy or an internal room divider.
We help turn your glazing requirements into a compatible specification, checking the system, glass build-up and opening before the final order is agreed.