When DuraBilt Exteriors, Inc. does a roof, all layers of the existing one gets ripped off down to the sheathing (plywood). Then, we clear the sheathing of nails and other impediments. At this time, any rotted plywood would be replaced. Next, we install an ice damn material and metal drip edge. Ice damning goes on all eaves, rakes, valleys, and around all protrusions. We then install a fiberglass embedded underlayment, instead of the usual, lesser quality 15lb. tarpaper. Only after all the preparation work is done, will our experienced mechanics install your new roof shingles, ridge vent, and hip and ridge caps, leaving your home with a new look and watertight.