Every once in awhile, I'm asked to
use a V-crimped valley flashing
profile. Typically, it's when I'm
installing a metal roof where a
roofs of different pitches.
The rationale behind the V-crimp is
that it will prevent the steeper roof
runoff from running back up the adjoining
shallow roof. I've seen it specified
for asphalt shingle roofs, but I prefer to
use a closed valley. The protruding ridge
of the V-crimp can easily be damaged if
someone accidentally steps in the valley.
A cardinal rule is never to step in a
valley, but accidents happen, and a misshapen
V-crimp is unsightly and difficult
I use a 10-foot brake to form the Vcrimp.