So you have a builder contract and thus also a consumer construction contract. The delay is defined in §650 of the Building Code. From the moment the delay occurs, compensation is due (also according to the Building Code). This is usually (I take a quote from the internet, so I don't have to write so much):
- Additional rent that the buyer must pay due to the delay
- Lump-sum compensation, provided this was agreed upon in the purchase contract
- Loss of rent, if it was planned to rent out the property
- Additional moving costs, if another move is necessary due to the delay
- Costs for storage of furniture
- Additional travel costs between home, daycare, school, and workplace
- Commitment interest from the lending bank. Banks charge buyers so-called commitment interest in case of delayed disbursement of the individual installments. The buyer can claim reimbursement of these from the builder.
- Compensation for loss of use if only lower-quality living space is available to the buyer during the period of delay. In 2014, the Federal Court of Justice ruled that the buyer of an apartment completed late by the builder is entitled to fictitious loss of use.
But first, the delay must have occurred. And until then, more or less a lot of water flows down the Rhine.