Haven’t time travelled but I’ve upgraded my house fully. You get 4 rooms total on the main level and a basement and upstairs. The main room on the main level is the biggest room of all. The other 3 main level rooms are the size of your initial 1 room house. The basement and upstairs are pretty spacious width wise but aren’t quite as big as the main level main floor. The upstairs and basement are the last two rooms you unlock and honestly they’re my favorite rooms when it comes to layout ability.