Remove existing shingle roof to skip sheathing, install 1 2 cdx plywood, install ice abd water 6 from eaves, 9 in valleys and 3 in from rake edges & around penetrations, remaining exposed area of deck to be covered by synthetic underlayment. Install drip edge & starter shingles to entire roof perimeter. Install owens corning trudefinition duration series yr arch shingles in estate grey color with matching cap shingles. All flashing sush as around chimney & vent stacks to be replaced.