Backerboard makes an excellent surface for tile adhesive to bond onto.
If you have sufficient sub-floor thickness (3/4 inch or more but should go by tile manufacturer's recommendations) you can get away without backerboard. But if you want some insurance againt any flexing in the floor and to prevent cracking, backerboard properly installed can increase the structural integrity of the floor.
But if you have a good even surface of sufficient thickness of plywood, it is possible to lay tile without backerbaord.
If you have sufficient sub-floor thickness (3/4 inch or more but should go by tile manufacturer's recommendations) you can get away without backerboard. But if you want some insurance againt any flexing in the floor and to prevent cracking, backerboard properly installed can increase the structural integrity of the floor.
But if you have a good even surface of sufficient thickness of plywood, it is possible to lay tile without backerbaord.
