"Home Guy" wrote in message
...
" wrote:

high attic humidity from lack of ventilation can also shoten roof
lives, and worse damage the decking

You solve high attic humidity by having a proper vapor barrier between
your ceiling and the attic space above it, as well as having proper
soffit ventillation.

Soffit vents are for "intake" of ventilation, where the cooler air
infiltrates. You need additional vents to "exhaust". Power vents are much
like your information you have, USELESS. They don't work in the winter.

A vapor barrier does nothing for the attic as far as heat loss to the attic
in the winter. Heat WILL still escape into the attic, even with PROPER
INSULATION. The vapor barrier is for the "interior" or "thermal envelope"
of the structure.

At least read up on this stuff, since you have no real experience with it.
Here's a hint, read about condensation. You probably think a cold glass of
iced tea in the summer, is leaking tea through the glass.