This house had older 3 tab shingles on it and was beginning to leak. We first tore all of the existing shingles off the roof and disposed of them, next we replaced a couple pieces of plywood that were rotten, while the sheets were off we discovered there was a broken truss so we jacked that back up and reinforced it. We always go through every sheet of plywood on the roof and make sure they are nailed down securely. Next we put all the valley tin down and put the snow and ice shield on the bottom 3 feet of the house. We Then put synthetic felt on which is a better product than the traditional tar paper. Next we install new laminated shingles the roof, after a complete clean up the job is complete.