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Wind and Snow Loads: Greenhouse Safety in Slovenia

Kako so naši rastlinjaki konstruirani za ekstremne razmere.
May 8, 2026 by
Termoplast
Wind and snow loads, safety of greenhouses in Slovenia
Photo by ART JIROUSEK on Unsplash

Slovenia is a weather-diverse country, from the Primorska burja to the mountain snow on Pohorje. A greenhouse suitable for Murska Sobota is not necessarily suitable for Kranjska Gora. In this article, we show how Termoplast constructs greenhouses for different regions.

120 km/h
max wind speed (storm)
250 kg/m²
max snow load
10 years
Termoplast warranty on polycarbonate

Slovenian weather regions

Slovenia has 4 main weather regions with different loads:

  • Primorska: strong burja (up to 200 km/h in the Vipava Valley), low snow
  • Central Slovenia: moderate winds (60-90 km/h), medium snow loads (80-120 kg/m²)
  • Gorenjska and Koroška: abundant snow (up to 200+ kg/m² at high altitudes)
  • Prekmurje: stable weather, but frequent summer storms with heavy local rain
Important: Before buying a greenhouse, check the ZRS (Building Institute of Slovenia) maps for wind and snow loads at your location.

Wind loads

Wind acts on a greenhouse in 3 ways:

  1. Frontal pressure, the greatest force
  2. Lift on the roof (like on an airplane wing), pulls the greenhouse out of the ground
  3. Vibrations (resonance), fatigue of joints

Important safety elements:

  • Ground anchors: concrete foundations, anchor plates, ground screws M16+ (Termoplast standard)
  • Aerodynamic profile: rounded roof shapes (lower lift force)
  • Strong diagonals: cross-bracing between side frames
  • Closed doors and windows in the wind, an open greenhouse is 5 times more loaded

Our greenhouses are tested for wind speeds up to 120 km/h (standard model) or 150 km/h (Premium model with additional reinforcements for the Primorska region).

Snow loads

Snow has different densities:

  • Fresh powdery snow: 50-100 kg/m³
  • Old, packed snow: 200-300 kg/m³
  • Wet snow + rain: 400-500 kg/m³

At 50 cm of old snow on a 20 m² greenhouse roof, the load is 1500-3000 kg. This is why cheap constructions fail in the first winter.

Termoplast construction elements:

  • Main frame: square tubes 40×40 mm (galvanized steel)
  • Roof bearers: every 60 cm (cheap alternatives have 80-100 cm)
  • Roof slope: 25-35° (snow slides down by itself)
  • Polycarbonate 4-6 mm: withstands 200-400 kg/m² static load

EU standards and norms

EU norm EN 13031-1:2019 defines 5 classes of greenhouses:

  • Class A: professional commercial (norm for all loads)
  • Class B: semi-professional (reduced standards)
  • Class C: hobby greenhouses (basic standards)
  • Class D: temporary/seasonal
  • Class E: decorative

All Termoplast hobby models meet class C, and premium models (Sigma, Profi) meet class B for professional use.

Preparing the greenhouse for extreme events

Before predicted strong winds (60+ km/h):

  • Close all doors and windows
  • Check that the anchors are secure
  • Remove all loose objects from the surroundings (pots, tools)
  • After the storm, inspect the joints and screws

Before a snowstorm:

  • Place internal supports under the main bearers (wooden slats 4×5 cm, every 1 m)
  • Remove snow after 20 cm with a long plastic shovel (NEVER metal!)
  • In extreme forecasts (50+ cm in 24h), consider removing the roof panels as well
"A greenhouse built for 'normal Slovenian weather' is not enough. Termoplast models are designed for 50-year extremes, the snow of 2014, the storm in Postojna.", Termoplast technical director

10-year warranty on polycarbonate

Termoplast offers a 10-year warranty on polycarbonate panels. Proven quality.

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