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Reply to "OSB VS Plywood"

Jonathon,

Interior Grade plywood may delaminate faster than OSB, but Exterior Grade does not!  Exterior Grade can take moderate direct water exposure for up to six months without delaminating.  The reason is, that it is made with waterproof glue, while OSB and Interior Grade Plywood are not.  That is why I only use the Exterior Grade on all repairs, whether an interior or exterior repair.   (Sooner or later, for one reason or another, water is always going to leak into or spill onto plywood inside a house!)   What good is OSB if the wood chips are held together with water soluble glue?

If you got involved in the construction industry around 30 years ago, that is about 10 years after the time that contractors really shifted big time to the much cheaper OSB.

I heavily researched all of this online about 15 years ago,  and came across studies from Virginia Tech that confirmed that given equal thickness, even interior grade plywood is always stronger than OSB if properly laid with the exterior grain running perpendicular across the underlying rafters or joists, assuming properly spaced joists.

At the big box stores, you can tell the Exterior Grade from the Interior Grade because the Exterior Grade has green stripes painted on the butt edge of the plywood, while the Interior Grade is painted with black stripes on the edge.  The number of stripes corresponds to the thickness of the sheet of plywood.   Nominal 3/4 inch plywood, for instance, has 5 stripes.

And, as you will see, the Exterior Grade plywood can cost almost double what the Interior Grade costs.  :-)

About a year ago, it was running at $81 a sheet.  :-O

Mannyrock

OGR Publishing, Inc., 1310 Eastside Centre Ct, Suite 6, Mountain Home, AR 72653
800-980-OGRR (6477)
www.ogaugerr.com

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