Ordering pre-cut tempered glass is the fastest way to finish a deck or balcony railing — but tempered glass cannot be cut or ground after it leaves the factory, so the measurements you send us have to be right. This guide walks through how to measure glass railing panels for aluminum, Regal and Vista systems.
1. Measure the opening, not the glass
Always measure the clear opening between the posts (for framed systems) or between the spigots/standoffs (for frameless systems), at the top and again at the bottom. Decks are rarely perfectly square, so use the smaller of the two readings.
2. Subtract for the channel and gaps
For framed aluminum and Regal/Vista railing, the glass sits inside a channel with a vinyl insert and rubber setting blocks. You need a gap on each side so the panel drops in without binding:
- Width: subtract roughly 1/2" total from the clear opening (about 1/4" per side).
- Height: account for the channel depth top and bottom — typically the panel height equals the post height minus the top and bottom rail allowance.
If you are matching an existing panel, measure the actual glass, not the opening.
3. Frameless spigot glass
For 12 mm frameless spigot glass, panel size is driven by spigot spacing and the pre-drilled holes. Send us the spigot layout and hole centres and we will confirm the panel size and cut-outs.
4. Watch the guardrail gap
BC building code limits the gap below a guardrail glass panel (generally no more than 4"). Keep your bottom gap compliant when you calculate panel height.
5. Double-check thickness and edges
Confirm the glass thickness your system takes (6 mm for most framed railing, 10 mm or 12 mm for heavier or frameless applications) and that you want polished, flat-ground edges — standard on our panels.
Not sure on a tricky opening? Send your measurements or a quick sketch and our team will size it for you. Get a quote → or browse glass panels.