Snow load zones

In Germany, Austria, and Switzerland, snow load plays a crucial role in the structural design of roofs. Depending on the geographical location, so-called snow load zones are defined, indicating the maximum snow load a building can expect. These zones are particularly important for roof planning and significantly influence the selection and installation of photovoltaic systems. This article explains how snow load zones are defined, why they are relevant for building owners and PV installers, and how CLEVER-TILE ® offers a reliable solution for regions with high snow loads.

What are snow load zones?

Snow load zones indicate the expected weight of snow on a horizontal surface. They form the basis for the structural design of roof constructions and roof-mounted systems, such as photovoltaic modules. The classification is divided into several levels and is based on historical weather data, altitude, and regional climatic characteristics.

Why is snow load so important?

• ❄️ Snow weighs more than you think: Wet snow can reach more than 400 kg/m².
• 🏠 Excessive load can lead to roof collapses – especially in the case of flat and pitched roofs.
• 🔩 PV substructures must also be able to safely bear this load permanently.

Classification of snow load zones in Germany

In Germany, snow load zones are subdivided according to DIN EN 1991-1-3 / NA:2010-12 (formerly DIN 1055-5) as follows:

• Zone 1: Low snow load (e.g. Rhine plain, Northern Germany)
• Zone 1a: Transition zone with medium load
• Zone 2: Increased snow load (e.g., low mountain ranges)
• Zone 2a: Elevated transition zone (e.g., foothills of the Alps)
• Zone 3: Very high snow load (e.g., Alpine region, Allgäu, Berchtesgaden)

The exact zone allocation is determined using special maps and can vary considerably even within a municipality – especially with increasing altitude.

Influence of altitude on snow load

In addition to the zoning, the snow load is adjusted according to the altitude of the construction site. A rule of thumb: For every 100 m difference in altitude, the snow load increases significantly. Above 800 m above sea level, separate values apply, which are determined using standard tables or calculation formulas.

Snow loads in Austria and Switzerland

Austria:

The Austrian standard ÖNORM EN 1991-1-3 regulates snow loads in Austria. Here, too, classification is based on zones and altitude. In mountainous regions – such as Tyrol or Vorarlberg – snow loads exceeding 6 kN/m² can be expected.

Switzerland:

In Switzerland, the SIA standards apply (e.g., SIA 261). Due to its alpine location, the highest snow load values in Central Europe are found there. Particularly in Valais, Graubünden, and the Bernese Oberland, roofs must withstand extreme conditions.

Relevance for photovoltaic mounting systems

Photovoltaic systems must be able to safely bear not only their own weight, but also additional wind and snow loads. In areas with high snow loads, a particularly robust substructure is mandatory – as are well-designed fastening systems that do not damage the roof covering.

Typical requirements:

• 🛠️ Reinforced roof hooks or mounting brackets
• 🧱 Non-penetrating solutions for protecting bricks
• 📏 Static calculations for every assembly situation

CLEVER-TILE ® – The solution for snow load zones

CLEVER-TILE ® is an intelligent tile replacement solution specifically designed for regions with demanding requirements. Thanks to the use of particularly robust material and a separately usable roof hook, the system offers maximum safety – even in Zone 3 and on roof pitches exceeding 30°.

The advantages at a glance:

• ❄️ Tested for high snow loads
• 🔩 No need to cut the roof tiles
• 🪛 Compatible with many brick types such as Marzari
• 📐 Ideal load distribution in the roof structure

Planning guidelines for building owners and specialist planners

Anyone planning a PV system should check the following points early on:

• 📍 Snow load zone and altitude of the property
• 🏗️ Roof and rafter statics
• ⚙️ Selection of a mounting system with tested load transfer
• 📜 Proof to be provided to the building authority or insurance company

Conclusion: Safety begins with snow load

Snow load zones are a crucial factor in the planning and implementation of rooftop PV systems. Those living in regions with high snow loads – whether in the Black Forest, the Allgäu, or the Alps – should not compromise on the mounting system. CLEVER-TILE ® offers a sustainable, safe, and roof-friendly solution that performs reliably even under extreme conditions.