Handyman deck construction practices were noted at a recent home inspection in Bellingham.  Here you see deck boards unprofessionally installed over OSB sheathing at an exterior deck platform where the OSB sheathing is completely deteriorated.  OSB sheathing is not rated for exposure to the elements and will deteriorate quickly if allowed to get wet.  It certainly isn’t an acceptable material for exterior deck systems.  In this case, the deck boards will need to be completely removed, OSB sheathing removed, and then deck boards installed again.  I think in this case, the homeowner was attempting to provide shelter to the underlying exterior storage area, not realizing that it would deteriorate in short time.