Floor plan of our double garage - ideas, feedback?

Baulast means my neighbor and I go to the notary, who then records in the land register that the wall on his boundary may also be 4m high??

No. Try using your search engine and type "rhein-pfalz-kreis". Then search for Baulast on the Rhein-Pfalz-Kreis website and click on the first result. Or ask the site manager.