I have pulled up the old linoleum in my bathroom and found lauan as the underlayment. After doing some research it seems unanimous that the lauan be removed for a ceramic install and I plan to do so. I hope its not glued... My subfloor is 3/4 OSB. Will I need an underlayment between the OSB and 1/4" cement board. What are my options? Joists are 2x10 16" oc 13' spans. Deflection is about L/458.