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BS 6180 line loads: what 0.36, 0.74 and 3.0 kN/m mean
A line load is the horizontal force a barrier resists along its top, in kN per metre. Here is what the figures mean, where each applies, and what they do not tell you.
By the SW Glass workshop team· Published · 5 min read
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A balustrade's line load is the horizontal force it has to resist along its top edge, at handrail height, measured in kilonewtons per metre (kN/m). BS 6180 designs barriers to loads taken from BS EN 1991-1-1 and its UK National Annex, which sets them by what the building is used for. Our balustrade checker prints them: 0.36 kN/m for stairs and landings in a house, 0.74 kN/m on that house's balcony, and 3.0 kN/m in a shopping mall.
What does kN/m mean on a balustrade?
A kilonewton (kN) is a unit of force. "Per metre" means the force is spread along the barrier: every metre of its length has to resist that much, pushed horizontally along the top at handrail height. It is the load that decides whether the barrier stays up, and it goes through the glass whenever there is no handrail to take it.
A quick example shows how the unit works. A 3 m run at 0.74 kN/m has 2.22 kN pushing along its top edge in total (3 × 0.74). That arithmetic is only to explain the unit. It is not a design: a barrier is checked against each load case for its panels, its fixings and the structure they are fixed into.
What are the three load figures?
The checker's load table gives three figures for each kind of building. They are alternative load cases, each checked on its own. They are never added together.
| Load figure | Unit | What it represents |
|---|---|---|
| Line load | kN/m | A horizontal load per metre run along the top of the barrier, at handrail height |
| Load on the infill | kN/m² | A load spread over the face of the panel, like a crowd leaning on it |
| Point load on the infill | kN | A single load on any part of the panel, wherever it is worst |
The load on the infill is the case that usually sets the thickness of an infill panel. Toughened and laminated glass answer the point load very differently, which is one reason the glass make-up is specified rather than guessed.
Which load applies to which building?
The load depends on the building, not on how the balcony looks. In the checker's own words, the same frameless panel is a 0.36 kN/m job in a house, 0.74 on that house's balcony and 3.0 in a shopping mall. These are some of the rows the checker prints, with its labels:
| Where the barrier is (checker label) | Line load (kN/m) | Load on the infill (kN/m²) | Point load on the infill (kN) |
|---|---|---|---|
| Domestic stairs, landings and floor edges | 0.36 | 0.5 | 0.25 |
| Domestic balcony, Juliet balcony or roof edge | 0.74 | 1.0 | 0.5 |
| Flats, hotels and other residential | 0.74 | 1.0 | 0.5 |
| Shops and retail areas | 1.5 | 1.5 | 1.5 |
| Assembly areas, shopping malls and crowds | 3.0 | 1.5 | 1.5 |
Each row has a precise definition of the occupancy behind it. For example, the domestic stairs row covers areas within or serving one single-family dwelling, but not external balconies or roof edges. Where overcrowding can occur in a shop, the assembly row applies instead. Read the full table and the definitions in the balustrade checker rather than picking a row from a summary.
This is general guidance. For your project, follow the regulations and manufacturer instructions that apply, and ask your building control body, engineer or Gas Safe engineer where needed.
Does a higher load mean thicker glass?
Not on its own. As the checker says, there is no single answer for thickness. It comes from the horizontal load for that occupancy, the height of the barrier, the span between fixings, how the glass is held and what has to happen if a pane breaks. That is why the checker refuses to name a thickness.
The handrail changes the answer. Where a handrail on its own supports takes the line load, the glass is an infill and only has to resist the loads on its face. Where there is no handrail, the barrier is free-standing: the glass carries the line load itself. BS 6180 is explicit that a free-standing barrier with no handrail should be laminated glass. Toughened laminated is the usual specification there, because a broken laminated panel stays in one piece on its interlayer.
Who decides the load and signs off the barrier?
Not the checker, and not this article. The checker reproduces the standard's design loads for the case you describe and checks your height against Approved Document K. It does not size a panel, design a fixing or certify a barrier. Sizing a barrier panel is an engineering calculation against the load case, the fixing, the interlayer and what must happen if a pane breaks. Have the supporting structure and its fixings checked by an engineer, and confirm with your building control body.
When you are ready, our balustrade designer lets you draw the run and choose the fixings. Every design is checked by a person and comes back as a quote. For Juliet balconies, use the Juliet balcony designer. Our help page on glass balustrades covers the rest of the process.
Where to go next
Run your position through the balustrade checker to see the full load table, the definitions and the height rule.
Questions we get asked
Which load applies to a domestic balcony?
The checker's row for a domestic balcony, Juliet balcony or roof edge prints 0.74 kN/m line load, 1.0 kN/m² on the infill and 0.5 kN point load. The domestic stairs row, at 0.36 kN/m, does not cover external balconies or roof edges.
Does a Juliet balcony need the same load as a full balcony?
In the checker's table, Juliet balconies share a row with external balconies and roof edges, including those serving a single-family dwelling: 0.74 kN/m.
Is BS 6180 a legal requirement?
BS 6180 is a code of practice: it gives recommendations for designing barriers. The Building Regulations are the law, and Approved Document K gives guidance on how to meet them in England. Ask your building control body what applies to your project.
Can your checker tell me what glass to buy?
No. It prints the standard's loads and checks your height, but it is not a structural calculation or our certification of anything. Ask us for a specification with your load case, the opening and how you want it held.
Ready for the next step?
Find measuring instructions and order support in Help and advice, or ask the team about your project.
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