re: Laying New Floors - OB Recs

First pull the hardie board up now sub floor prep you need a straight edge or you can stretch a string and nail it down this will show you high low spots do this every few feet and go both ways. high sand it down low use a self leveler you should not have more than 3/16 deviation in 10 feet. You are looking to get the floor flat. Now if you use self leveler you will need to glue the floor down to the leveler and nail the rest but self leveler is not ideal to nail through the leveler. good quality glues are available Loba wakol is probably the best use the trowel they recommend. Yes you can rent a nailer and and diy just read this you will be fine. LINK