Exterior shading elements are now a standard part of homes, office buildings, public and industrial buildings. From an aesthetic and practical point of view, a sub-panel option is often chosen, as the added boxes on the façade are less attractive.
16.12.2025 ISOparts s.r.o.
Exterior shading elements are now a standard part of homes, office buildings, public and industrial buildings. From an aesthetic and practical point of view, a sub-panel option is often chosen, as the added boxes on the façade are less attractive.
But if we want to get the under-mounted preparation for exterior shading right, we find that there are no precise rules. Often the project documentation only contains schematic designs for the louvre boxes, and then hasty or compromised solutions are made on site, which can lead to problems such as façade defects or thermal bridges.
The correct approach, therefore, is to follow the recommended ETICS practices and associated standards for the implementation of CCA. This is because the louvre box for the louvres is more a part of the ETICS than the louvres themselves. For this reason, we have based the principles of the PURbox system solution on these guidelines, providing our customers with the confidence that the solution is technically correct and defensible.
Because each building carries its own specifics, the ISOparts recommended solution must be consulted with the designer and the façade system contractor.
The ISOparts system for soffit elements is based on four basic principles:
1 - Space for louvre installation
The main objective is to allow the installation of external louvres so that they are not visible once retracted. The size of the space for the blinds depends on the type of slat - standard (Z90, C80, S90) and tapered (Z70, C65, S65). The height of the space depends on the type of slat and the height of the window, and the depth depends on the type of slat. In the PURbox ISOparts system, the recommended depth is 135 mm for standard slats and 120 mm for tapered slats. These values are recommended but can be adjusted to suit the specific situation.
2 - Insulating the lintel
The space above the window where the louvre is to be fitted must be insulated to prevent heat loss. It is necessary to remove some of the insulation at the lintel and connection joint, but at the same time ensure effective compensation. In the PURbox ISOparts system we use PUREN MV PIR insulation, which provides optimum thermal protection.
3 - Connecting the PURbox and lining to the window frame
An important rule of thumb is to cover the window frame and connecting joints with a minimum of 30-40mm as required by ETICS recommended practices and standards. The PURbox is installed with a frame cover of 30mm of insulator, which allows accurate installation even if the window is not ideally seated. The same rule applies to prefabricated lining, which covers the sides of the window with 30mm of insulator.
Standard PURbox assembly detail
Mounting detail of prefabricated lining
4 - Material composition of the PURbox
Quality of workmanship and functionality are key. That is why we only use original materials from PUREN GmbH. The greatest added value is the way the parts are bonded - thanks to the knowledge of the material properties, details can be handled efficiently and surface finishes can be made possible without the risk of peeling.
The materials used - Purenit structural board and PUREN MV PIR insulation - work together with the façade, resist temperature influences and building chemistry, manage moisture well, are lightweight, strong and the PIR insulation provides excellent thermal insulation properties.
These four rules form the basis of the PURbox ISOparts system solution, which is the optimum sub-wall preparation for the installation of exterior shading technology. The products are protected by the PURbox® trademark, valid throughout the EU, and provide quality construction details that delight both users and builders.
Benefits of using a system solution
- complies with ETICS regulations and building standards
- eliminates thermal bridges and improves the energy efficiency of the building
- installation is fast, clear and minimises errors
- Variability allows adaptation to different louver types and construction details
PURbox ISOparts is a modern and comprehensive system that standardizes the under-mount preparation for outdoor shading. Thanks to clearly defined rules, quality materials and a high technical level, it brings the assurance of correct execution and long-term reliability.
