Wind load on windows: how big can a window actually be?

At a glance

• Germany is divided into four wind zones – the wind blows harder on the coast than in the south.

• The load on a window increases with building height and is greatest at the corners of the facade.

• Your window specialist works out case by case whether the size you want is feasible.

• Salamander myWindow offers PVC profile systems for large glazed areas, fabricated by window specialists across Germany.

What is wind load on windows?

Wind load is the force the wind exerts on a surface – as pressure on the windward side, and as suction on the leeward side and at the edges of the building. A window has to withstand both without the profile and glass bending too much or the seals giving way. Because the load increases with the surface area, it is the deciding factor for the size of large windows and sliding doors.

What does the wind load on a window depend on?

The starting point is the wind zone where you live. Germany is divided into four zones: large parts of southern Germany are in the lowest, while the North Sea and Baltic coasts and islands are in the highest. What really matters, though, is the load at the exact spot where your window sits.

• Wind zone: Determines how strongly the wind blows at the location. On the coast, a window has to perform better than inland.

• Building height: The wind gets stronger the higher you go. A window higher up takes more than one on the ground floor.

• Surroundings: Open land increases the wind, dense buildings slow it down. A house on the edge of a field is loaded differently from one in town.

• Position on the facade: The strongest suction forces occur at corners and edges. Corner windows often need a stronger design.

• Window size: The larger the area, the greater the force. Large formats need stiffer profiles, reinforcement or a mullion.

Tip: At your very first meeting, tell your window specialist where the house is, how tall it is and which windows are at the corners of the building.

How big can a window be?

The maximum window size isn’t a figure in a table – it’s the result of a calculation for your building project. On one side is the wind load at the installation site; on the other is what the window can handle: profile, reinforcement, glazing and fixings. If that isn’t enough for the size you want, you don’t have to do without large glazed areas. Your window specialist can use stronger reinforcement, choose a profile system with a greater installation depth or divide the unit with a mullion. The wind resistance class under EN 12210 shows how much wind a tested window can withstand – for example C3.

Which PVC windows are suitable for large windows in windy locations?

PVC windows with a large installation depth, stiff profiles and the right reinforcement are suitable. The Salamander myWindow range includes these profile systems:

• bluEvolution92: a large profile system for demanding building projects that also takes special glazing.

• greenEvolution_straight: slim sightlines with an all-glass look for floor-to-ceiling windows.

• evolutionDrive_plus: a sliding system for large openings; the sash slides parallel to the wall.

A real-life example: Haus Am Briel, Konstanz

The “Haus Am Briel” apartment building in Konstanz has ten storeys and floor-to-ceiling windows overlooking Lake Constance. What made the project special were the high requirements for wind pressure and wind suction. The windows installed use the bluEvolution92_flex profile system from Salamander myWindow in black.

Salamander myWindow manufactures the profile systems; the windows are fabricated, designed and installed by window specialists in your area.

Your next step

In the Visualizer you can see how large glazed areas look on your facade and with the partner search you’ll find a partner near you who will check the size you want.

Note: This article does not replace a structural calculation. The design by your window specialist is binding.