You may have already experienced it. One day your neighbor rings your doorbell and asks you for a signature. He is planning a "small" structural change to his property and, according to the building authority, "only" needs your neighborly consent.
What would be the impact of my signature?
If you immediately grant neighborly consent with your signature, you would already waive any legal remedies against the building permit sought by your neighbor.
"The signing of a neighborly declaration of consent can lead to a violation of good faith due to an impermissible exercise of rights in the event of the subsequent assertion of neighborly rights protecting third parties, since the signatory behaves inconsistently if he waives such rights but later asserts such rights (cf. Verwaltungsgericht Gelsenkirchen, judgment of 12.11.2019 - Case No. 6 K 5557/17)."
Only if you wait to sign the agreement do you reserve the right to assert your rights for the time being. In any case, we would recommend that you seek comprehensive advice from a lawyer before signing. Should your neighbor violate public-law building regulations (e.g. § 6 BauO NRW distance areas) with his planned structural alteration, you as a neighbor:in principle could take action against this.
What breaches can I take action against as a neighbor?
As a neighbor, you cannot take action against any violations of applicable building law, but only against those violations that affect you. Therefore, there would have to be a violation of a so-called norm protecting third parties. However, if the authorities ask for your consent, such a violation is usually obvious.
What legal remedies do I have?
You can protect your rights by filing an action together with the competent administrative court in due time. However, you should bear in mind that such an action does not have a suspensive effect (Section 212a of the German Building Code); your neighbor may therefore still be in possession of a valid building permit and the building project would not be "stopped". If you would also like to temporarily prevent the realization of the building project, we would also have to file an application for suspension of the execution of the building permit by way of urgent legal protection.
Before taking legal action, a comprehensive assessment should naturally take place, and we will be happy to advise you on this.
If you have any questions, please do not hesitate to contact me.
Attorney Dennis Wiegard
Düsseldorf, January 8th, 2021