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Re: [Phys-l] paint your roof?



Does the mansard roof have a raised edge so that the cool air can
pool?

Some "flat portions" of mansard roofs do have a slight upward slope
around the outside, but nothing like a parapet. If they have this, it's
because the low channel near the edge can act like a gutter, and that
allows the water to be channeled to particular spots before it drains
from the roof.

Mine has about an eighth-inch-per-foot slope from the center clear to
the edges so it drains everywhere and does not pool water. Because it
is not perfectly planar, after a rain there are a few small puddles
usually less than a foot in diameter. Sometime when the air temperature
is close to but above freezing I will have to go up there and see if any
of the puddles are frozen.

Michael D. Edmiston, Ph.D.
Professor of Chemistry and Physics
Bluffton University
Bluffton, OH 45817
(419)-358-3270
edmiston@bluffton.edu