Re: Can't add a room to house

We had an bug sounding a lot like your issue. Is your game fully updated? This should've been fixed in one of the last updates:
https://answers.ea.com/t5/Bug-Reports/Fixed-Known-Issue-Simoleon-and-Ticket-charge-for-re-sizing-or/td-p/6862043/jump-to/first-unread-message