HeyBub wrote:

When, if ever, do you need to be concerned about having too much
negative pressure in the attic?

What do you klowns think is happening?

You think there is some big vacuum cleaner sitting on your roof, sucking
air through your ceiling just because you have too much venting?

Excellent point!

Stupid point!

This could easily happen with aggressively powered
fans and insufficient, or no, soffit vents.

What are the odds that someone is going to have powered roof fans *and
no* soffit vents?

And think about this: Even IF you are somehow creating a negative
pressure in the attic that IS pulling air through the ceiling - SO
WHAT? This is going to be happening ONLY IN THE SUMMER. ITS NO BIG
DEAL IF IT HAPPENS IN THE SUMMER. It's in the winter when you don't
want that to happen, and who's going to turn on their roof fans in the
winter ????