Lumikuorma

Lumikuorma is the vertical load exerted by snow on surfaces such as roofs and walls. It is a central consideration in structural design and is typically expressed in kilonewtons per square metre (kN/m2) or kilopascals (kPa). The magnitude depends on how much snow accumulates, its density, and how wind redistributes snow on the surface.

Snow density varies with freshness and moisture; dry, powdery snow weighs less than wet, compacted snow. Wind can cause drifting and higher loads on exposed edges, eaves, and on the windward side of the roof. Roof shape, slope, and thermal conditions also influence how snow collects and settles.

Calculation and design: Engineers determine a ground snow load for a site from local data or building codes, then apply adjustments for roof geometry, exposure, height, and temperature to obtain the design snow load on the roof. The design load is combined with other loads according to the applicable standard.

Standards and regulation: Snow loads are defined in national building regulations and in European standards such as EN 1991-1-3 (Snow loads). Local annexes provide region-specific factors. Finland and other Nordic countries typically use published snow-load maps and climate data as part of the design process.

Practical considerations: Snow removal, monitoring during extreme winters, and, if necessary, structural reinforcement or safeguards to resist excessive lumikuorma. Proper maintenance reduces the risk of overload and related structural damage.