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The diagram follows gravity, wind uplift and lateral actions from the roof surface into rafters or louvers, beams and posts. It continues through every connection, base plate and anchor into the foundation and finally the supporting soil, emphasizing that one weak or undocumented link interrupts the claimed structural path.
Key takeaways
- Do not use a temperate-climate specification in snow country.
- Adjacent roofs can create drifts.
- Operational snow sensors do not replace structural capacity.
On this page
Accumulation patterns
Roof shape, thermal conditions, exposure and nearby higher surfaces influence snow depth. Louver pockets, gutters and attached-building interfaces can collect ice or drifted snow.
Use and maintenance
A system that requires louvers to remain open or a canopy to be retracted in snow needs a reliable operating plan. Safe snow removal methods must avoid unbalanced loading and damage to panels or mechanisms.
European framework for actions including self-weight, imposed, snow and wind actions.
Ground snow is not roof snow
Structural provisions transform regional hazard into roof actions using exposure, thermal condition, importance, slope and geometry. Adjacent roofs, parapets and height changes can create drift or sliding concentrations. A generic kilograms-per-square-metre claim is incomplete unless the load definition, distribution, combinations and permitted operating state are identified.
Movable roofs need an explicit snow strategy
Documentation should state whether louvers or fabric remain open, close automatically, or must be cleared before accumulation; it should also address freezing and loss of power. “Open during snow” does not remove snow effects from frames, gutters, motors or partially obstructed blades, and it relies on an operating action that must be realistic and documented.
US model-code provisions for residential patio covers; only applicable where adopted.
Primary sources and scope
European framework for actions including self-weight, imposed, snow and wind actions.
US model-code provisions for residential patio covers; only applicable where adopted.
Official standard hub for US structural actions including wind, snow, rain, seismic and load combinations.
Official application guides for wind, snow, rain and seismic provisions; guides support but do not replace the standard.
Cite this page
Pergola Wiki Editorial Team. “Snow and ice actions.” Pergola Wiki. Reviewed 24 July 2026. https://pergola.wiki/articles/snow-load/