Rotten Wood under 6 year old shingles

This home had rotten wood under 6 year old shingles. We installed soffit vents, ice & water on the whole 3/12 slope, on all the eaves and valley. We also installed a skylight, bath vent, ducting & soffit vents, new OSB, and Owens Corning Teak colored shingles. Not only did the roof have incorrect ventilation, it also had a slope issue which kept water standing on the roof. What a shame to have to replace a roof after only 6 years! Now the homeowner won't have to worry for approximately 50 years!