External window sill / Compriband

Hello, before the warranty period expires, I would like to clarify a few points. The first point concerns the plastering of the exterior window sills. After some plaster at the end of a window sill crumbled, I noticed that a thin leaf spring can be inserted quite far there, see photos. This actually contradicts what I believe I once read. Isn't it the case that before plastering, a compressible tape must be applied at the top and down the side over the end piece of the window sill?

Hello,

I would be very happy if someone could take the time for a response, even a very short one.

Merry Christmas!

Is it not the case that before plastering, a compressible sealing tape must be applied above and laterally over the end piece of the window sill?

Yes, that is usually how it is done. Do you have photos from the construction phase?

Thank you nordanney,

sorry for the late reply, Christmas and all!

Unfortunately, I don’t have any photos for this, I wasn’t on the construction site at that time.
Then the thing with the Kompriband is clear.

Is a second sealing layer required beneath this type of windowsill and does the cavity below necessarily have to be foamed?

Thanks and regards

In timber frame construction, they are always present. Solid (or with ETICS) only if a driving rain-tight installation cannot be guaranteed. With ETICS and sliding piece as well as compressible tape and proper installation (e.g., no trade holes in the corner or properly sealed), you don’t need them.
Whether foam is used also depends on the installation situation. For ETICS, for example, there are slanted substrate insulations so that you don’t have to foam anything at all. But it depends on the installation situation.

In my DIY project, I foamed under the bench and also used it to glue the bench.

Thank you for the incredibly fast info!!!

We have built massively, I still need to check the Gewerkelech, we definitely don’t have wedges, I have to see what is underneath!

Thank you really very much for your helpful answers, nordanney!