You are correct on your definition of OSB.
But MDF and OSB are not the same nor do they perform the same.
I do believe use of MDF in RV applications is a really BAD idea no matter
the exposure rating.
I know this has been a heated discussion in the past here but....Sticking my
neck out....
Here is a link to which is better, OSB or Plywood.
As you may notice they don't compare MDF
And as you may notice they don't blatantly say which is better. But I feel
after reading it that plywood is better but marginally.
http://www.askthebuilder.com/304_Plywood_and_OSB_-_Which_One_Is_Better_.shtml
And here is a little something about Exposure ratings and plywood.
http://www.apawood.org/pablog/index.cfm/2006/7/10/Choose-the-right-exposure-classification-of-plywood
Both Plywood and OSB are offered in Exterior, Exposure 1 and interior
ratings.
I personally wouldn't recommend interior rated wood for use in older RVs due
to moisture problems that crop up from time to time.
--
Warren
1989 GMC R2500 HD Suburban.
1953 Airstream Cruiser Travel trailer.
Western KY
> Joann,
>
> OSB is oriented strand board, I think. Basically compressed wood chips.
> MDF, medium density fiberboard, is a finer quality and basically compressed
> sawdust. Both are heavier than plywood and cheaper.
>
> Bill Kerfoot
> WBCCI/VAC/CAC #5223
> 1973 Dodge W200 PowerWagon
> 1977 Lincoln Continental
> 1979 23' Safari
> 1954 Double Door 29' Liner
> Orange, CA