Modern architecture relies on large glass surfaces and clean façades. At the same time, there is a growing demand for plasterable sun shading that is invisibly integrated into the insulation layer. In practice, top-mounted elements are typically used for this purpose, installed together with the window. However, this eliminates the option of fixing the top of the window directly to the structural shell – a statically relevant factor that should be considered early in the planning process.

Every window has a defined moment of inertia and corresponding stiffness – depending on its material and design (e.g. PVC, aluminium or wood). Whether this stiffness is sufficient depends on several factors:

  • Window size and geometry
  • Installation position within the façade
  • Wind load zone and building location

If the maximum permissible deflection is exceeded during structural calculation, the window must be additionally stabilised.

As an expert, you know that determining the structural analysis based on the selected window profile is the responsibility of the planner or client. Discover solutions to improve the wind load resistance of solar shading systems.

Standard top-mounted elements do not include window-stabilising or load-transferring components between the window and the building structure. Structural optimisation of roller shutters, external venetian blinds and window awnings is optionally possible and can be achieved through various measures listed here.

Please note: The decision on which measures to apply must be made by the executing party. WAREMA does not perform structural calculations.

Learn about ways to increase window stiffness and improve structural performance. Availability may vary by country.

A steel window adapter profile reinforces the upper part of the window frame and reduces deflection. In many cases, this measure is sufficient to meet the requirements.

  • The steel adapter profile is available in two versions (long and short). The long version is suitable for window frame depths from 70–92 mm, while the short version can be used for frame depths from at least 70 mm (no upper limit). These profiles increase the moment of inertia ly of the window (recommended for widths > 1600 mm). Moment of inertia of steel adapter profile: long: ly = 8.3 cm⁴ | short: ly = 2.4 cm⁴.

If the permissible deflection is exceeded despite the reinforced window adapter profile, structural brackets are required. They transfer loads into the building structure and ensure the long-term functionality of the window and sun shading system.

If the required standard classes cannot be met by the window frame or a frame reinforcement, optional structural brackets are available to improve stability. These are already integrated into the box and must be securely fastened to the building structure. These brackets help absorb and transfer wind loads acting on the window into the building.

This structural bracket is used for large frame widths and can be fixed outside the box. It is available for all new-build top-mounted systems and transfers the loads from large window elements, e.g. lift-and-slide door systems, into the building structure.

The WAREMA structural bracket tool supports planners and window manufacturers in reliable structural design. Based on project-specific window data – including dimensions, material and installation situation – it can be used to calculate

  • whether an adapter profile is sufficient,
  • when additional stabilisation is needed, and
  • where structural brackets should be positioned for optimal load transfer.

This allows all necessary measures to be clearly defined in the planning phase.