Sorry to resurrect this old thread, but I am finally going to have a new floor put into the bathroom of this house. My contractor says he can put in 2x6 joists every 16" to reinforce the bathroom floor, and is installing marble. Again the floor is framed with 4x8s on 48" centers with 1.125" plywood. Will this be strong enough for marble over concrete backerboard once the additional 2x6's are installed?
Thanks for any clues!