If my memory serves me right then you need to pay for the room. Go to the quintuplets brother and pay them silvers and they will fix the room for you. You can get money by mining or fishing.
Ps: I have 4 quest, where all of them being i need to recruit new guild members/build rooms. And the only girl that I can level up is Lucy, but the hint is just wait a while (that being over 14 in game days i have waited) so I'm stuck...
