If the existing plywood subfloor is weak, you may want to add ... which is a 6-millimiter-thick sheet that's manufactured from cement-based materials. Backer board is especially important to ...

OSB is generally cheaper than plywood. Depending on thickness, a 4 X 8 sheet costs between $15 and $43. When installing OSB on a subfloor, the strength axis (the longer edge) should run ...