I am having my 3 tab asphalt roof replaced, with a laminate asphalt.( looks
like a shake shingle design), 3 ft. ice and water barrier on entire
perimeter of roof.
Currently there is galvanized valleys, the roofer suggested that I do away
with that and do what they call a closed valley install.With a 3 ft ice
barrier underlayment put down before the shingles in areas,where the
current galvanized valleys are now.
I have heard of that before, it does look like a cleaner install as the
galvanize weathers and discolors.