I have a set of architect drawn plans for a house. There's an A-Frame
section in the middle with vaulted ceiling (i.e. no 2nd floor) in the front
and a 2nd floor loft in the back. The plans specify the use of 3x10s on 12"
centers. These would be 23ft long with no support other than at the ends.
Seems to me that's pushing it a bit too far and the floor for the loft will
be very spongy. Any thoughts?

Also, there is a bathroom in that loft and I really prefer to put down
ceramic tile. I'm concerned that a flor that has much deflection will cause
grout joints to constantly crack.

Thanks