i have 2x10 rafters on 16"OC on a late 50's ranch. there is 3/4"x6" boards as the subfloor in which we re-hammered down the nails to the rafters. we then glued + nailed 1/2" Douglas fir plywood to this subfloor every ~4" and then screwed inbetween the rafters the plywood to the subfloor every ~4". it still squeaks a little but feels solid. is this ok for directly laying tile down onto?