"stevie" wrote in message ...

My concern is that the attic is not adequately ventilated. I'm not sure
that enough air is getting through the siding vents, then through the
plywood 4x8 holes.

Consult your municipal building office. It ought to be
able to tell you how many square inches of ventilation
each type of attic needs for 100 cubic feet of volume.
Minima are probably prescribed in the building code (for
new construction.)
--
Don Phillipson
Carlsbad Springs
(Ottawa, Canada)