you normally get the money for your apartment only when the other person can move in as well. that's called transfer of risk. he could take you as a new tenant for a certain period. but that would only work if the buyer of your apartment wants to use your apartment as a rental property. that would of course be optimal.
but if the apartment is in demand, a later sale would be more sensible. the bank will certainly recognize your property as equity, but you have to pre-finance the amount. that could be done, for example, with a very short, smaller loan. once the property is paid off, you could also possibly buy the land on which the condominium is registered with the still existing land charge (might save registering a land charge again, etc.).
in the end, you have to calculate what makes more sense.
sell immediately:
- move once more, maybe you can stay as a tenant in the building
- with a lot of luck, you find someone who waits until you move out (which usually makes no sense as a buyer and has only disadvantages – you might not even get any money...)
- there are usually costs incurred as a tenant (wherever)
+ you have your equity available immediately
sell later:
+ you have time to choose the land, no one pressures you
+ you wouldn’t have to move or anything else
- you have to pre-finance your equity in the form of the property
- thus you pay interest on your equity
- you have to calculate when the house will be finished (i.e., when the money is spent) and when the old property is sold to keep the loan period as short as possible
- you have the risk of having to sell the property in the end (probably not an issue in Hamburg)
what kind of sum are we even talking about here? otherwise, of course, you can try to sell the apartment with a right to stay. maybe someone will agree to that (especially if demand is high). notarized certification states until when you have to move out. for that, you have to know when your house will be ready. if you don’t even have a piece of land yet, that’s pointless at the moment :)