Completion significantly delayed - trades not completed

Isn't the retention enough to fix the defects?

That is currently the exciting question. Since we moved in, we have detected various defects. Just last week, the window installer responsible for fixing the defects pointed out to us that the sealing of the roller shutter rails/window frames was not done properly on all windows. In addition, the front door does not meet the Kw70 standard, so it must/would have to be replaced. We immediately set a deadline for the builder. Note: the windows were installed by another company. We will have our building expert, who is however not officially appointed or whatever the term is, come again and hear his opinion on this. The problem is the loan, for which we already pay standby interest monthly, and when all orders that have to be awarded to third-party companies are added up, our retention might possibly not be sufficient. How is it actually with the entry in the land register, if the contract is not fulfilled by the builder, does it still remain there, and do we have to sue to get it removed??