While I still think it's possible the mold growing on my attic ceiling on
the roof sheathing may stukk be a special case scenario, such as snow
sitting on the roof on a winter day when the temp and humidity high, I'm
starting to agree that my attic does, in general, need more ventilation,
even if my adding the ventilation doesn't wind up solving the mold issue.

The reason is because my attic's internal temperature, as measured near the
attic's ridge, was 105 degrees today. Today, in the northeast, it's a
perfectly sunny day. Outside, the temperature is only 62 degree in the
shade, and the temperature in direct sunlight was measured at 96 degrees
(likely would be a bit higher without some breezes).

Is a 105 degree attic temperature (as measured near the attic's ridge), on a
day such as I just described, a normal attic temperature for a properly
ventilated attic? If not, what would my attic's temperature be if it were
properly ventilated. (My attic is a crawl space, meaning you can't stand up
in it.)

As for humidity, I haven't yet seen any indication humidity problem in my
attic, as measured by a hygrometer. I still think mold growth may be a
special case, such as a snow-sitting-on-roof scenario described above, or if
there were several very high humidity days in a row. In other words, I'm
not seeing much evidence of high humidity in my attic, although it likely
does need more ventilation as indicated by today's 105 degree attic
temperature.

Let me know what you think.

Thanks.

Jeff