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wood diaphragm edge / roof venting

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Drilled edge blocking is common to vent roof spaces when batt insulation is 
used to eliminate heat and moisture.  In a cathedral ceiling attached to the 
bottom of the roof framing, vent holes would be required at each rafter 
space.  Per the code, the size of these vent holes is based upon whether 
there are vents at the eave only (1/150 of area) or eave and ridge (1/300 
area).  The vents at ridge and eave are more effective due to heat rising.  A 
continuous ridge vent is not an option because it would cause a diaphragm 
discontinuity.  Is there any published information reagradingimpact on 
plywood diaphragm strength of drilling holes in plywood at the ridge (say (2) 
- 2" diameter at each space each side of ridge?)
Also, in a recent SEAOC seminar mention was made of observations made in 
older tilt up buildings with foil insulation nailed to bottom of framing 
where the joist hangers had rusted away due to prolonged exposure to moisture 
without ventilation.  Has anyone encountered this and what is a solution?
Thanks-

Paul Franceschi S.E.