MDF vs. OSB for Subfloor

[Mark]

Greetings Group,

My buddy is rehabing an old farm house and is having some flooring replaced. He's got a quote on the work where he has the option of either MDF or OSB for the subflooring and was wondering which would be better. I did a little Googling and see both mentioned as used for this, but I personally thought the OSB would be more appropriate. I'd generally heard of MDF as for cabinets and such, and didn't think if it as having the kind of strength needed for a load-bearing application like a floor.

Thought I'd run the issue past the group to see if there was any experience (good or bad) with either.

Thanks!

Mark

[Mook Johnson]

mdf will swell when wet.

better grades of OSB wont.

[Eric in North TX]

Mdf is what you use if you are leaving and don't care if a leak happens and the entire house melts and runs down the gutter.