Scaffolding in high winds, snow and winter

Why does a scaffold have two wind limits?

There are two situations to plan for. The first is the wind in which people may still work on the decks. The second is the storm the empty, tied scaffold must survive. Not every manual states both. HAKI, whose system scaffolding is sold in the UK through its dealer Enigma, covers wind in its international user’s manual (2024) only through the tie layout: ties every fourth metre of height, and a separate calculation for every sheeted scaffold. It gives no wind speed at which work must stop, so on a HAKI scaffold that figure has to come from the firm’s own procedure, which is exactly what NASC’s SG46:24 is written for.

Where a manual does give numbers, the gap between the two limits is large. The Norwegian Jamax user guide is one example that states both. Work must end at a velocity pressure of 200 N/m², which the guide equates with a gust of 17.9 m/s. The scaffold itself is designed for up to 1,120 N/m²; where calculations show a site can see more than that, the vertical spacing between ties must drop from 4 m to 2 m (Jamax user guide, section 14.1). The guide also tells you to work out the local wind loads from Eurocode 1 for the place where the scaffold stands.

German approvals show a second detail that matters for long jobs. The approval for Layher Blitz 70 steel frames was calculated with a "standing time" factor of 0.7, which assumes the scaffold stands for no more than two years (DIBt approval Z-8.1-16.2, Annex B.pdf)). A scaffold left up through three winters is outside that assumption and needs its own check.

How do you read a forecast against those limits?

Forecasts give a mean wind and, separately, gusts. A manual limit written as a gust must be compared with the gust figure, not the mean. The Met Office publishes the Beaufort scale with speeds in knots and m/s:

Source: Met Office Beaufort scale. Put the Jamax figures next to that table with care: 17.9 m/s is a gust, while Beaufort describes mean wind, so compare it with the gust forecast. The manual warns that a forecast mean of force 5 in open country, or the low end of force 7 in town, can already produce gusts that strong. A scaffold on an exposed gable or at the corner of a tall block sees more than the forecast for the postcode.

When must work on the scaffold stop?

In Great Britain the duty is general. Regulation 4(3) of the Work at Height Regulations 2005 says work at height may be carried out only when the weather does not jeopardise the health or safety of the people doing it. The regulation names no wind speed, so the employer's limit comes from the system manual, a TG20 compliance sheet or the scaffold design. The NASC publishes SG46:24 Adverse and Inclement Weather Conditions on how scaffolding firms decide when to stop and resume work in high winds, heavy rain, snow, ice and extreme temperatures.

In the US the rule is sharper. 29 CFR 1926.451(f)(12) prohibits work on or from scaffolds during storms or high winds unless a competent person has decided it is safe and the workers are protected by a personal fall arrest system or wind screens. The same paragraph adds that wind screens may only be used if the scaffold is secured against the wind forces they bring.

Two practical points follow from the manuals rather than the law. Loose material is the first thing the wind takes, so boards, offcuts and sheets go down or get lashed before the crew leaves. And the stop decision belongs to the forecast for the shift, not to how calm the morning feels.

What has to be checked after a storm?

Under regulation 12(3)(b), equipment exposed to deteriorating conditions must be inspected each time exceptional circumstances that could jeopardise its safety have occurred, and HSE gives high winds as the example (HSE scaffolding guidance). In the US, the competent person inspects before every shift anyway under 1926.451(f)(3). The full list of what to look at is in our inspection checklist; after wind, start with the ties, the base plates and anything clad.

The NASC's January 2024 alert after several scaffold collapses during Storm Henk is a reminder that the storm is rarely the only cause. The confederation said the failures should have been avoided and told clients to check scaffolds against the TG20 compliance sheet, the manufacturer's instructions or a bespoke design (ScaffMag, 5 January 2024).

What do nets and sheeting do in a storm?

They turn an open frame into a sail. HSE says never to sheet or net a scaffold without telling the people who designed and erected it, so they can confirm it takes the extra load. How much the force on each tie rises once a scaffold is sheeted, and how the tie pattern changes, is set out in scaffold ties and anchoring. Our guide to load classes covers the decks; the tie pattern for a clad scaffold comes from the manual or a design.

Wind can also lift. Jamax sells storm brackets that hook under the top platforms, because in strong wind the highest deck can rise off its frame, and it makes the erector or inspector responsible for judging when they are needed. The Layher approval covers netted scaffolds only up to stated force coefficients for the net and scaffold together, so a denser net than the one assumed is a design change, not a detail.

How much snow can a scaffold deck carry?

Snow is a load like any other, and a heavy fall can exceed it. German guidance counts heavy snowfall among the events that trigger a special inspection precisely when the weight of snow on the scaffold exceeds the permitted imposed load (DGUV Information 201-011, section 5). HAKI's manual says snow and ice must be removed at once in winter (HAKI Universal assembly instruction, page 41), and Jamax asks for platforms to be cleared after snowfall.

OSHA is explicit about the people: 1926.451(f)(8) prohibits work on scaffolds covered with snow, ice or other slippery material except to remove it, and (f)(13) bans debris building up on platforms. Shovel snow off the deck onto a controlled area below, never over the guardrail onto a pavement.

What happens to the ground under a scaffold in winter?

Frozen ground feels like concrete, and it is not a foundation you can trust through a thaw. In a 2000 interpretation letter, OSHA wrote that compacted soils swell and heave with the water they contain, that the freeze and thaw cycle can happen within a single day, and that a footing which was level in the morning may settle by afternoon. It asks the competent person to approve the foundation daily and again when conditions change, such as sun or rising temperatures (OSHA interpretation, 1 August 2000). HSE's guidance asks for a firm, level foundation and warns about soft ground and hidden voids.

The cold also attacks the steel. Jamax warns that mud, snow or ice can block the bottom of frame standards, the trapped water freezes, and the tube can split beyond repair. It suggests storing frames in a heated store for a while after a winter strike so that ice plugs melt before the stock goes back outside. When you check base jacks after a cold snap, check the sole boards for movement and the tubes for frost cracks at the same time.

Is there a rule on lighting a scaffold in winter?

Yes, in Great Britain. Regulation 35 of the CDM Regulations 2015 requires every construction site and its approaches and traffic routes to have suitable and sufficient lighting, by natural light so far as is reasonably practicable, and secondary lighting where a failure of the main lights would put people at risk. On a scaffold that means the access ladder or stair, the landings and the decks where people walk at the end of a short day, not only the work face. Wet boards and frost on steel decks make every unlit step more dangerous.

ScaFix lays out the bays, lifts and tie points of a facade scaffold as a 3D model and a parts list before anything is ordered; it does not check wind loads.

This is planning information, not structural approval. Wind and snow limits, tie patterns and clad configurations come from the manufacturer's instructions, a TG20 compliance sheet or a scaffold design. In Great Britain the Work at Height Regulations 2005 and HSE guidance apply; in the US, OSHA 29 CFR 1926 Subpart L. A competent person must inspect the scaffold after any storm and before it is used again.

Frequently asked questions

Sources

Primary sources used for this article, with the date each was read.

• Jamax user guide, 4th edition rev. 2 (28 August 2025), sections 2.7, 8.9, 13 and 14 (read 23 October 2026)
• DIBt approval Z-8.1-16.2: Layher Blitz Gerüst 70 Stahl (2 January 2025).pdf) (read 23 October 2026)
• Met Office: The Beaufort wind force scale (read 23 October 2026)
• Work at Height Regulations 2005, regulation 4 (read 23 October 2026)
• Work at Height Regulations 2005, regulation 12 (read 23 October 2026)
• Construction (Design and Management) Regulations 2015, regulation 35 (read 23 October 2026)
• HSE: Scaffolding (construction safety topics) (read 23 October 2026)
• NASC SG46:24 Adverse and Inclement Weather Conditions (read 23 October 2026)
• ScaffMag: NASC raises alarm over recent scaffold collapses amidst high winds (5 January 2024) (read 23 October 2026)
• 29 CFR 1926.451 General requirements (Cornell LII) (read 23 October 2026)
• OSHA standard interpretation on scaffold foundations, 1 August 2000 (read 23 October 2026)
• HAKI Universal assembly instruction (HAKI AB, 2021) (read 23 October 2026)
• HAKI Universal user’s manual, international version (HAKI AB, 2024) (read 23 October 2026)
• DGUV Information 201-011 (January 2023) (read 23 October 2026)