Bob F wrote:

In the summer, if I had a choice between:

a) pulling 1000 cfm of air out of my attic using powered vents -
with 950 cfm coming from the soffits (and/or gable-end vents) and
50 cfm coming from ceiling leaks - or

b) having NO powered vents (only passive vents) and therefore
only getting 200 cfm of passive air movement out of the attic
(and 0 cfm from ceiling air leaks) -

It's a no -brainer which one is better for the house and the roof.

As long as you don't care what it costs to run the A/C. Trying to
cool an extra 50 cfm of exterior air continuously is going to
COST.

That cost might be more than offset by the heat load I'm taking away
from the interior ceiling area by ventilating the attic with 950 cfm of
outside air vs 200 cfm of passive air.

Numbers like 1000, 200 and 50 (cfm) are all just hypothetical, but I
still assert that interior air leaks into the attic are trivial (for any
home built in the last 50 years) - not counting any bad practices like
venting bathroom or kitchen fans into the attic.