author: Petra, 30.08.2023. in Blogs Venetian blinds We often encounter the question of why blinds with PurBoxes are more advantageous than blinds with classic cover sheets. Let's take a closer look and explain the main differences. In case you already have a finished house and facade and decide on external blinds, the choice of exposed external blinds is clear. Blinds with visible cover sheets can be installed at any time, and dealing with an under-window box would be both time and cost-intensive, and it would not help with insulation. Exposed external blinds with visible cover sheets on a finished facade However, if you don't have a finished house yet and are considering blinds for under-window installation, you can compare two options - blinds with prepared boxes or try to make the boxes for blinds yourself and embed blinds with cover sheets into the facade. Installation complexity - PurBoxes If you opt for this option, from ordering to the installation of blinds, it will take an average of 21 - 28 days. You can measure PurBoxes yourself or order them based on the window manufacturing documentation. Blinds can be ordered along with them (dimensions are automatically calculated), or you can purchase them later. We will produce the boxes (and blinds) tailored to your needs and deliver them within 10 days. The equation is simple - installation of 1 PurBox = approximately 1 hour. Once you have all the boxes installed, you can proceed with additional insulation on the remaining parts of the house, and after insulation, you can apply the facade directly to the boxes. Within 21 days of ordering, we will deliver custom-made blinds, and here the time requirement is again plus or minus the same - 1 blind = 1 hour. Completed installation of PurBox The major benefit of PurBoxes is their simplicity of installation - you can easily handle it yourself. There is no need to organize other construction work separately, and in this single step, you have a solution for blinds, their insulation, and a suitable base for applying the facade after insulation. Installation of external blinds into prepared PurBoxes PurBoxes consist of two materials - Purenit and PIR insulation. Thanks to them, the boxes for blinds are very strong yet lightweight. They can be easily processed with common construction tools. Installation complexity - cover sheets If you are considering the second option, which is installing cover sheets under the facade, you need to consider greater organizational complexity on the construction site. It is not always the case, but it involves several interrelated construction activities, so it is usually unrealistic to embed the sheets yourself, and a installation company is often called in. From choosing and contacting the installation company, providing an approximate price quote, on-site measurements, to ordering, it takes an average of up to 48 days. Only after the facade is completed can external blinds be measured, and their delivery then takes approximately 21 days. The total time is thus around 63 days. The installation of cover sheets consists of several steps: First, brackets for blinds are anchored to the load-bearing structure of the house. A major mistake is anchoring the brackets directly into the masonry because it creates thermal bridges and transfers exterior heat to the masonry. The construction installs insulation for the translation, which is usually made of extruded polystyrene. These are three technological steps that cause delays - gluing the insulation, leveling it, applying adhesive, beads, and final facade. There is also the issue of connecting the insulant to the window frame, creating a detail that is often not aesthetically pleasing, and cracks can develop over time. Only then comes the installation of cover sheets. Underneath, a base plate must be fastened. It has no insulating effect and serves only as a facade carrier. Installation of under-window aluminum casings Even if all the mentioned steps are carried out diligently, there is still a risk that the sheets may expand and become visible on the finished facade. Only then are blinds measured, you wait for delivery, and then you can install them. What are the differences in the final outcome? With PurBoxes, we can create a space for blinds and insulate the translation and the window connection sparrow in a single construction step. Purenit boxes do not react to temperature changes, moisture, or construction chemistry and do not expand. Thanks to the PIR insulation, there are no thermal bridges. Cover sheets do not address the translation insulation or the window connection sparrow. The sheets conduct heat well, leading to expansion and cracks in the facade. When additional insulation with polystyrene is underestimated, massive thermal bridges can form. Demonstration of changes in length and shape of aluminum sheets PurBoxes have the lowest depth requirement in the contact insulation system. / Cover sheets are more demanding in terms of space in the contact insulation system, even when the correct installation process is followed. You can install Purenit boxes yourself, and the installation is not time-consuming. / Because the under-window casing with cover sheets consists of multiple elements and requires coordination between installers and facade workers, it is a more time-consuming installation. Purenit boxes with blinds are approximately 12% more expensive than blinds with cover sheets initially. However, the difference is repaid multiple times over the following years when your home will not lose heat, and your facade will remain as beautiful in 10 years as it is now - without cracks and protruding sheets. PurBoxes are the ideal solution for under-window external blinds. / Cover sheets are the ideal solution for exposed external blinds.