How to measure for a glass balustrade

Glass balustrades are made to measure — every panel is cut to your run length and height before toughening. There is no adjustment on site. Accurate measurement at order stage prevents costly remakes and delays. This guide walks through what to measure, what to photograph and what to confirm before you place an order.

What you need

• Steel tape measure (5m or longer for most runs)
• Spirit level or laser for checking level edges
• Notebook or phone to record each side
• Photos of the substrate, corners and any existing fixings

If the structure is not yet built, work from structural drawings and mark the guarding line on the slab edge before concrete is poured.

Step 1 — Mark the guarding line

Identify where the glass will stand. On a terrace, this is usually the open edge of the finished floor — after tiles, decking or paving. Mark a continuous line along that edge.

For base channel systems, the channel often sits in a recess — the structural detail may be set back from the visual edge. Confirm the manufacturer’s setting-out dimension so the recess is formed in the right place during construction.

Step 2 — Measure run length

Measure the total length along the guarding line for each straight side:

• Straight run — one dimension, corner to corner or corner to free end.
• L-shape — side A length and side B length, measured independently.
• U-shape — sides A, B and C.

Measure at floor level along the intended glass line, not at handrail height (walls may taper). Record dimensions in millimetres.

Do not subtract for panel gaps — the supplier divides the run into equal panels with nominal spacing between panes.

Step 3 — Measure glass height

Measure vertically from finished floor level to the required top of the guard:

• 1100mm is the usual height for external balconies and terraces in UK dwellings.
• Internal landings may be 900mm in some cases — confirm with Approved Document K.

If you plan a top handrail, state whether height is to the top of glass or top of rail. The order height should match what building control approved.

Step 4 — Note corners and returns

For L- and U-shaped runs, note:

• Which corners are 90° internal angles
• Whether the return continues guarding or meets a wall
• Any steps in level along the run — each level change is a separate guarding element

Walls at the end of a run may form a closed end — measure only the open edge requiring glass.

Step 5 — Check the substrate

Before ordering, confirm the fixing method suits what is built:

Mount

What to check

Channel

Recess depth, width, drainage fall

Spigots

Slab thickness, reinforcement, anchor access

Posts

Base plate positions, bolt embedment

Send photos of the edge, underside of the slab and any structural drawings. Spigots and posts need pull-out capacity; channels need a straight, level bearing.

Step 6 — Panel widths and sight lines

Manufacturers split the run into equal panel widths up to a maximum clear width per pane — typically around 1300mm. Longer runs mean more panels, not wider glass.

If a panel alignment matters — for example lining up with a mullion below — state it at order stage. Equal splits may not match existing architecture unless you request asymmetric sizing (may affect cost).

Step 7 — Confirm and order

1. Double-check every side length and the height.
2. Confirm fixing type — channel, spigots or posts — and hardware finish.
3. Confirm handrail option — none, slimline or round.
4. Agree glass type — clear, tinted or frosted — and thickness with your supplier.
5. Remeasure on site if more than a few weeks pass before manufacture.

Record who verified dimensions and the date. When the panels arrive, compare labels to your schedule before installation — toughened glass cannot be cut to fit.

Vant Glass manufactures made-to-measure glass balustrades and Juliet balconies in Britain, with free UK mainland delivery. Browse balustrades and guarding or call 03330 902 592 to discuss your run.