ᐅ Poor Installation of Window Sills – Is the Supplier Responsible?

Good evening

Today we wanted to start with the exterior facade. Unfortunately, the plasterer noticed that the window sills have probably not been installed correctly. There is a clearly visible gap at the back end of the window sill. (See photos)

My architect says it’s fine, but I don’t really trust him. The window supplier has not been reachable so far.

The plasterer suggests replacing all the sills. Of course, this will cost me almost 2,000 euros.

What do you think?
Is there any chance I can hold the window supplier liable? Has anyone had experience with this?

Thank you

Whether this is a major defect or not – don’t just let someone else fix it. The window manufacturer is responsible for corrections and also has the right to carry them out.