Engineered hardwood floor over chipboard

I think I would put down an underlayment, just saw some stuff at HD in 4 foot squares, never used it but it looks okay, or you can go with 1/4" ply

Dave

there are many different types now so you should check the instructions for the manufacturer and the material that you want to install.

some of the floating floor products use a foam material under the product so that would cure any of the problems with the ruff surface of the osb but if you need to level the floor or if your product does not use that method you may be better off using sheets of luan plywood screwed to the osb

which ever method you use I would strongly suggest that you install rows of screws into your joists through that osb so you don't endup with squeeks that will drive you crazy later.

good luck bob marencin