You can buy a new room if your first binweevils nest do not have enough space to store furniture and other items. If you are not a member of the binweevils tycoon, only get one extra room but if you are a Bin tycoon you can buy lots more.. I got info from BinWeevils.com while you are leveling up, we’ll be able to buy up to 8 rooms.
1. First open map go to Shopping Mall
2. Go to 2nd floor then enter to Rigg’s Property Shop
3. Please choose a room from the plans
4. After you buy it go to your nest, you should have the new space now.