One reason I would ventilate a roof that is being sheathed is that it may
some day be conditioned.
Also, the temperature inside may be warmer than the exterior temp. and thus
a condensation will occur.
I live in Northern Calif. and do ventilate whenever possible since I have
seen the effects of no
ventilation and problems with ceiling members and sheathing damage due to
water and moisture.
"Wayne Whitney" wrote in message
I'm building a new, detached, residential garage in a Mediterranean
climate (Berkeley, CA). Is there any need to ventilate a flat roof
over unconditioned space in this context?
Without any space conditioning, I don't see how the roof assembly
could develop a temperature gradient that would lead to condensation.
But perhaps I am missing something? I will have a gypsum board
ceiling on the interior, so the joist bays will be enclosed.