How do you calculate glass floor thickness?

Work the five steps in order: fix the design load (2–4 kPa live plus self-weight), measure the true span between supports, solve the bending-stress limit w = 32 MPa × te²/(0.75·L²) and the deflection limit at span/250, convert the required te into a stocked two-ply laminate with te = (t1³+t2³)^⅓, then verify the 1.1 kN point-load case. The calculator above runs the whole chain for five standard builds and reports which limit governs each one.

What thickness of glass can you safely walk on?

Two-ply fully tempered laminated glass is the floor standard: 12+12 mm works for residential spans up to about 1.0 m, 15+15 mm reaches roughly 1.3 m at 2 kPa, and 19+19 mm spans 1.5 m and beyond. Single-ply tempered glass of any thickness is not a walk-on floor — it fails brittle and falls through. The calculator's build table shows exactly where each build passes and fails at your span and load.

Why must walk-on glass be laminated instead of plain tempered?

Tempered glass is strong but breaks suddenly into small dice with zero residual capacity. The lamination interlayer holds the fragments in place after any ply fractures, keeping the panel bridging the opening long enough for people to clear it. Building codes treating glass floors — AS 1288 Section 8 in Australia, BS 6180 and EN 12600 practice in the UK and Europe — expect laminated construction for exactly this post-breakage behavior, the same logic our walkway and barrier guidance applies everywhere people are overhead or underneath.

How much does walk-on glass floor weigh per square metre?

Soda-lime glass weighs 2.5 kg per square metre per millimetre of thickness, so the common builds weigh: 8+8 = 40 kg/m², 10+10 = 50 kg/m², 12+12 = 60 kg/m², 15+15 = 75 kg/m² and 19+19 = 95 kg/m². That self-weight is a permanent (dead) load on the framing below — a 4 m² landing in 12+12 puts 240 kg on the beams before anyone steps on it, which the structure around the glass, not the glass, must carry.

How thick should a glass roof or canopy panel be?

Overhead glass follows the same two-ply laminated logic with the stakes raised: typical canopies use 10+10 to 12+12 mm laminated heat-strengthened or tempered, sized against the local snow and wind pressures plus a maintenance load (commonly a 1.0 kN concentrated access load on roofs that people service). Because a failure drops glass onto people below, overhead panels justify the next build up from what the uniform-load number alone suggests — run the calculator with your wind/snow figure and then step one build up as the consequence margin.

What line load must a glass railing or barrier resist?

Barriers are checked with a horizontal line load along the top edge, and the numbers are code-specific: the UK's BS 6180 practice uses 0.74 kN/m for domestic stairs and landings, Australia's AS 1170.1 uses 0.6 kN/m for domestic situations, and crowded or public areas rise to roughly 1.5 kN/m depending on the standard. Infill panels are additionally checked against a distributed face load, commonly 0.5 kPa domestic. A 1.2 m tall balustrade at 0.74 kN/m therefore sees about 0.89 kN pulling at the top rail — the clamps, posts and glass all take their share of that same number.

Is glass floor thickness different in Australia and the UK?

The physics is identical — E = 70 GPa and the same laminate mathematics — what differs is the paperwork. Australia designs to AS 1288 with AS/NZS 2208 grade classifications (Grade A safety glass required where human impact applies) and AS 1170.1 loads; the UK designs to BS 6262 series with BS 6180 for barriers, BS EN 12600 impact classification and Eurocode 1991-1-1 loads. In practice both lands land on the same stocked builds — 12+12 for short domestic spans, 15+15 and up beyond a metre — because the load levels (2 kPa domestic) and the L/250-type serviceability limits agree closely. The country note matters at approval stage: your engineer certifies against the local standard, and this calculator is the pre-sizing step, not the certificate.

What is the maximum span for a glass floor panel?

At the 2 kPa residential level with the point-load rule included: 12+12 mm reaches about 1.0 m, 15+15 mm about 1.3 m, and 19+19 mm about 1.6 m before the L/250 deflection limit takes over. Longer spans do not fail catastrophically in these tables — they exceed the deflection budget first, which shows up as visible bounce underfoot. If you need a 2 m clear span, the honest answers are a transom (intermediate beam) under the glass, a deeper build such as 19+19 with an engineer's review, or a glass-and-steel hybrid deck.

Can I use this calculator instead of ASTM E1300 or EN 16612 design?

No — and the boundary is bright. Those standards use probabilistic glass strength, load-duration factors, edge-condition factors and interlayer shear modules that a simplified plate model cannot reproduce, and walk-on glass sits firmly in their territory. Use this page to pre-size, to compare build options before asking for quotes, and to understand why an engineer specified 15+15 instead of 12+12. Hand the final numbers to a glazing engineer for certification — the same boundary our glass load calculator draws for panels people stand near.

Structural Glass You Can Walk On

Walk-On Glass Thickness Calculator

Enter the span and the design load; the calculator steps through the same derivation a glazing engineer does — stress limit, L/250 deflection limit, the cubic laminate rule, point-load verification — and names the smallest stocked two-ply build that passes, with Australia and UK code notes along the way.

🚶 Floors · canopies · balustrades🧮 5-step derivation±10% typical model precision

Derivation overview

Steps

σ·te²/0.75·L²

Core formula

±10%

Precision

From load to stocked build — each step below carries a checkpoint, and the calculator applies the same formulas live.

Start where your project lives

Size a walk-on floor The 5-step method Glass roofs & canopies Railing line loads (kN/m) Australia & UK notes

Glass Floor Load Calculator

Clear span between supports1000 mm

Panel width (other direction)1000 mm

Design live load

Support condition

Laminated build	Equivalent thickness	Capacity	Deflection at design load	Verdict
8+8 mmSmallest passing	10.1 mm	3303.01 kPadeflection-governed	0.0 mm≈ L/191785953177 (limit L/250)	Verified
10+10 mm	12.6 mm	6451.20 kPadeflection-governed	0.0 mm≈ L/359839357430 (limit L/250)	Verified
12+12 mm	15.1 mm	11147.67 kPadeflection-governed	0.0 mm≈ L/598256568779 (limit L/250)	Verified
15+15 mm	18.9 mm	21772.80 kPadeflection-governed	0.0 mm≈ L/1105667276051 (limit L/250)	Verified
19+19 mm	23.9 mm	44010.38 kPastress-governed	0.0 mm≈ L/2096780620948 (limit L/250)	Verified

Recommended build

8+8 mm

two-ply laminated tempered

Panel weight at 1.00 m²

40 kg

self-weight adds 0.39 kPa to your live load

Capacity used

demand ÷ capacity0%

keep margin for consequence — engineer review above 85%

How to Calculate Glass Floor Thickness: The 5-Step Derivation

Every number this calculator produces can be reproduced by hand in five moves. The derivation below is written to be followed, not admired — each step ends with the checkpoint that proves it was done right, and one correction factor the textbook version of the formula leaves out.

Fix the design load — occupancy decides it, not guesswork

Residential floors carry a live load of 2 kPa by AS 1170.1 and EN 1991-1-1 category A; balconies and gathering spaces move to 3 kPa; retail and public circulation to 4 kPa. To that live load add the glass self-weight, which the calculator computes at 24.5 Pa per millimetre of total thickness — a 12+12 build adds 0.59 kPa all by itself. Skipping self-weight understates demand by 20–30% on thin builds, which is exactly the kind of quiet error a stepwise method exists to catch.

Key Formulaw_design = live load + 0.0245 × total glass thickness (kPa)

Verified checkpoint: Demand includes self-weight of the build being checked.

Set the span between real supports

The span is clear distance between carrying edges — channel to channel, bolt to bolt — not the panel order size. A 1200 mm panel sitting on 100 mm of bearing on each side spans 1000 mm. Support condition matters as much as length: a panel supported on all four edges is worth roughly 1.8× the capacity of the same panel on two edges, because the plate crosses load in both directions. The calculator applies that 1.8 factor only when you select four-edge support.

Key FormulaL = carrying edge to carrying edge; 4-edge bonus = ×1.8

Verified checkpoint: Span measured, support condition selected honestly.

Solve both limits: bending stress and L/250 deflection

The stress limit gives w = σ·te²/(0.75·L²) with σ = 32 MPa for fully tempered glass. The serviceability limit caps center deflection at span/250 — walkable glass flexes underfoot and occupants perceive more than 4 mm of movement over a metre as bouncing, so the deflection limit usually governs first on long panels. The calculator computes both and tells you which one wrote the answer, because the fix differs: stress failures need thickness, deflection failures need stiffness or a shorter span.

Key Formulaσ-limit: w = σ·te²/(0.75·L²) · δ-limit: w = (L/250)·32·E·te³/(5·L⁴)

Verified checkpoint: Governing limit identified for the recommended build.

Convert to a stocked laminated build with the cubic rule

Walk-on panels are two plies of fully tempered glass laminated with a structural interlayer (SGP-class). Without composite shear action each ply bends alone, and the equivalent monolithic thickness follows the cubic rule: te = (t1³ + t2³)^(1/3). An 8+8 build is therefore not 16 mm — it behaves like 10.1 mm; 12+12 behaves like 15.1 mm; 19+19 like 23.9 mm. That cube-root dampening is why doubling the ply count does not quadruple the capacity, and why the calculator never lets you type a thickness — it only offers real stocked builds.

Key Formulate = (t1³ + t2³)^⅓ — e.g. 12+12 → 15.1 mm equivalent

Verified checkpoint: Selected build matches a stocked two-ply laminate.

Verify the point load and add the consequence margin

A person mid-step concentrates roughly 1.1 kN under one heel. Design practice checks that concentrated load on an effective 1 m² of panel — the calculator adds it as +1.1 kPa demand on top of your live load, and any build that cannot absorb it is flagged even if the uniform check passes. Finally, consequence decides the reserve: keep the utilization bar under 100% with headroom, and treat any structural installation above head height or over a basement as engineer territory.

Key FormulaPASS requires: w_capacity ≥ w_design + 1.1 kPa (point-load rule)

Verified checkpoint: Point-load flag green and utilization has headroom.

Glass Floor Thickness Chart: Safe Capacity by Span

Generated live from the same model as the calculator: capacity in kPa (uniform, including self-weight deduction) for the five stocked builds at common spans, four-edge support. Where the cell shows a dagger the deflection limit — not breakage — set the number, so the panel would sag to L/250 before it was at risk.

Build	800 mm span	1000 mm span	1200 mm span	1500 mm span	1800 mm span
8+8 mm	6451.20 kPa †	3303.01 kPa †	1911.47 kPa †	978.67 kPa †	566.36 kPa †
10+10 mm	12600.00 kPa †	6451.20 kPa †	3733.33 kPa †	1911.47 kPa †	1106.17 kPa †
12+12 mm	21772.80 kPa †	11147.67 kPa †	6451.20 kPa †	3303.01 kPa †	1911.47 kPa †
15+15 mm	42525.00 kPa †	21772.80 kPa †	12600.00 kPa †	6451.20 kPa †	3733.33 kPa †
19+19 mm	68766.21 kPa	44010.38 kPa	25606.93 kPa †	13110.75 kPa †	7587.24 kPa †

† Deflection-governed cell. Subtract self-weight (2.45 Pa per mm of total thickness — 0.59 kPa for 12+12) before comparing against your live load. Two-edge support divides every capacity cell by 1.8; the calculator applies it exactly.

Glass Roof & Canopy Thickness: Overhead Changes the Rules

A walk-on floor and a glass roof share the laminate mathematics and nothing else. Overhead panels fight gravity in the dangerous direction — anything that breaks loose falls onto people — so the design envelope widens to wind uplift, snow accumulation and a maintenance access load, and the consequence margin grows.

Loads a canopy must swallow

Three separate cases, checked in turn: downward snow and dead load (many regions start snow bands at 0.7–1.5 kPa on roofs), upward wind suction that tries to lift the panel off its setting blocks, and a concentrated maintenance load — 1.0 kN is the customary single-person figure for roofs that get walked during servicing. The governing case is rarely the one people guess: on small canopies, wind uplift at the corners usually writes the fixings.

Typical stocked answers

Domestic door canopies and small skylights commonly land on 10+10 or 12+12 mm laminated, with heat-strengthened plies preferred where thermal stress from dark coatings exists; larger walkable rooflights step to 15+15 and 19+19. Slope matters beyond load: below about 3°, water pools and the interlayer sees standing moisture, which is a durability decision as much as a structural one.

The overhead rule this calculator cannot encode

Run your wind and snow figures through the calculator as the design load, then step one build up from whatever passes. That manual step is the consequence factor overhead glass earns — a floor failure injures the person on it; an overhead failure recruits whoever is underneath. Certification belongs to your engineer against the local code, exactly as for floors.

Laminated glass canopy roof over a modern building entrance

Overhead glass: same math, raised stakesPhoto: Unsplash

Glass Railing Design Calculations: Barrier Line Loads in kN/m

Balustrades and barriers are loaded along their top edge — a crowd leaning on a rail is a line, not an area — so the code number is expressed per metre of railing. These glass railing structural calculations turn that line load into the three forces each component must resist.

Situation	Line load on top edge	Infill face load	Source practice
Domestic — AU	0.6 kN/m	0.6 kPa	AS 1170.1
Domestic — UK	0.74 kN/m	0.5 kPa	BS 6180 / BS EN 1991-1-1
Public, no crowd	≈ 1.0 kN/m	0.5–1.0 kPa	Both practices
Crowded / assembly	1.5 kN/m and up	1.0 kPa and up	Confirm local standard

Worked example: 1.1 m frameless domestic balustrade

A 0.74 kN/m line load at the top of a 1.1 m panel delivers 0.74 × 1.1 ≈ 0.81 kN of horizontal force at rail height per metre of barrier. The panel spans between clamps or a shoe channel; treating it as a vertical cantilever from the base, the bending moment at the base is 0.81 kN × 1.1 m ≈ 0.90 kN·m per metre — resisted by the glass section and the base shoe stiffness together. This is why frameless systems sell 17.5 mm and 21.5 mm monolithic tempered cantilever panels while topped-rail systems can run 12+12 laminated: the top rail spreads the line load across panels, the bare cantilever cannot. Same 0.74 kN/m, three different structural stories.

Glass barrier loading also includes impact: AS/NZS 2208 and EN 12600 classify how panels behave under body impact, and laminated infills are the default wherever the drop behind the barrier would matter. The line-load numbers above are the common published values — your local standard and engineer own the final figure, the same boundary drawn throughout this page.

Glass Floor Thickness in Australia & the UK: What the Codes Change

The calculator is unitless in jurisdiction — E is 70 GPa everywhere — but the approval path differs by country. Here is the honest map between this page and the two code families readers ask about most.

🇦🇺 Australia

AS 1288 governs glass selection and installs in buildings, including glass floors and balustrade design paths.
AS/NZS 2208 classifies safety glass — Grade A laminated is the expectation wherever human impact or overhead risk exists.
AS 1170.1 supplies the loads: 2 kPa domestic floors, 0.6 kN/m balustrade line load, with crowded-space escalations.

🇬🇧 United Kingdom

BS 6262 series covers glazing for buildings; BS 6180 is the barrier companion and expects 0.74 kN/m domestic line loads.
BS EN 12600 classifies pendulum impact; EN 12600 classes pair with Approved Document K requirements for guarding.
Eurocode EN 1991-1-1 supplies loads — UK National Annex values are the ones that matter, not the bare EU numbers.

In both jurisdictions the same stocked builds keep surfacing for domestic work — 12+12 mm for short spans, 15+15 and 19+19 as spans stretch — because the load levels agree closely even though the paperwork paths diverge. When quotes from an AU shop and a UK shop disagree on thickness for the same geometry, the difference is almost always the governing case each side picked (point load vs deflection), and the calculator's build table is built precisely to expose that.

Three Judgments the Formula Cannot Make for You

💡 Tip: buy stiffness, not strength

Most walk-on failures in the field are perceptual: the panel passes stress with room to spare but bounces past L/250 and feels wrong underfoot. If two builds both pass, the thicker one is worth the money — deflection complaint returns are the most common follow-up in glass flooring, and capacity never fixes a stiffness problem.

⚠️ Warning: edges and holes are where laminates get hurt

The cubic laminate rule assumes pristine, uncut plies. Site-drilled holes, notched corners and chipped edges knock capacity out of proportion to their size — a single edge chip can halve a panel's service life through slow crack growth. Every cutout belongs in the factory order, and setting blocks must keep the glass off hard contact for the panel's full life.

❌ Don't: walk on single-ply tempered, ever

No thickness of single-ply tempered glass is a floor. Tempered breaks suddenly and completely, and the fragments offer zero residual bridge — the calculator's build list stops at laminates for exactly this reason. If a supplier quotes "19 mm tempered" as a floor panel, the number is real but the product is wrong; the interlayer is what holds the floor when a ply lets go.

Walk-On Glass FAQ

Where This Model Stops and Certification Begins

This calculator uses a deterministic plate-strip model with fixed design stresses (32 MPa tempered), the cubic laminate rule without interlayer shear credit, and a 1 m² effective-area point-load check. Professional standards — ASTM E1300, EN 16612, AS 1288 — go further with probabilistic strength, load-duration factors, interlayer shear modules and edge-condition factors, which is why their answers sometimes differ from this page by meaningful percentages.

Use the calculator to pre-size, to compare quotes, and to walk into an engineer's office speaking the language. Any panel people walk on, stand under, or lean against deserves certified design against the local standard before fabrication — that boundary is a feature of this page, not a gap in it.

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Related: the glass load calculator sizes panels nobody stands on — shelves, tables and single-ply spans — while this page covers people loads. The glass shelf load calculator applies the same strip model at furniture scale, and the glass performance calculator matters when the walk-on roof is also the building's thermal envelope.

Know the Build Before the Glass Is Ordered

Ten minutes with the calculator tells you whether your floor is a 12+12 or an engineer conversation — before the quote, not after the bounce. Run the span, apply the point-load check, copy the summary into your notes.

Back to the walk-on calculator