We received our windows and door on the second week of September. I was not in Regensburg, so Alex helped us receiving them. Then we were away 2 weekend for holiday, I missed the process of installing windows and door. Alex has done it all when I returned.
What I understand is he put a material called Dichtungband around the window frames and door frame, this material will expand after installing and it is waterproofed and it also has the effect like insulation.
We ordered our windows and door from https://www.sparfenster.de/ because they have windows that allow us opening to outside. The material of the frames are Alu/Holz. It takes about 2 months from ordering to delivering. We don’t know how good is the quality yet, we will find out after living in 🙂