What is typical
Most residential staircase and balcony railings use toughened glass in the 10 to 12 mm range, or laminated combinations where the structure or local practice calls for it. Frameless panels generally need to be thicker than panels held in posts or channels, because the glass itself carries more of the load.
What changes the answer
Span height, panel width, whether there is a handrail, who uses the stairs (children change the conversation), and the fixing method all matter. A railing is a safety element first and a design element second, so we confirm measurements and fixing before we confirm glass.
A rule of thumb
Never decide thickness from a photo alone. Send us photos and sizes on WhatsApp, and we will tell you what we would use and why, and where your local building rules say something specific, that wins.
Quick thickness guide by job
- Staircase with a top handrail: 10 mm toughened glass
- Frameless staircase or balcony without a handrail: 12 mm toughened, or laminated toughened
- High balcony or terrace where people gather: laminated toughened glass
- Steel post railing with glass infill: 10 mm toughened glass
Why laminated glass on high balconies?
Laminated glass is two sheets bonded with a strong interlayer. If one sheet cracks, the panel stays in place instead of falling out, which matters most where there is a long drop below. It costs more, so we suggest it where the risk justifies it.
Does thickness change the price much?
Yes. 12 mm glass costs noticeably more per sq ft than 10 mm, and laminated glass more again. The fixing system also changes the total. Compare systems on our glass railings page.
General guidance only; your application and local building rules decide the final specification.