One roofer I talked to a few years back (in NY) was against
the use of tar paper BECAUSE it increased condensation on the plywood or OSB
substrate underneath.
I don't know if this has ever been demonstrated empirically,
however.
Richard
Yeah it is funny, they perforate
the foil to allow moisture to escape and then we cover the other side of the
OSB with tar paper.
But I have yet to see a roof here and we regulary have high, 90%+
humidty, rot from condensing moisture. It has always been a leak.
I lived in New York for four years and the climate there is
different, did no roofing there so would not argue with him.
It cools down to 87F/97% humidity at night here
and there you can actually open a window and cool air blows in. That just may
make a difference. Not a lot of condensation at
87F, plus the next day the roof exceeds one forty.
Here on older houses the rafters get so dry it is like
splitting fire wood when you try to drive a nail in them. Another blow to
recycling.
