When krapabbel apartmets are going to apear?

I don't know when Krabappel Apts show up, but I think it is one of the very last buildings in the game, and there are a lot of quests to do before it shows up!

You won't get it through doing the Halloween quests like the Bad Dream House. The Halloween quests have no influence on the normal non-halloween quests. You just have to do them at the same time.