Observation: Asphalt shingles are not straight.
Performance Standard: The comers of individual shingles shall be no more than a total of 1/4 inch off the horizontal line of shingles, and these horizontal lines shall be no more than 1/2 inch out of parallel in 10 feet. Individual shingle tabs shall be no more than 1/2 inch off the vertical line of shingle tabs in either direction.
Corrective Measure: The remodeler will remove shingles that do not meet the performance standard and replace them with new shingles that are properly aligned.
Discussion: This defect is easy to prevent by carefully measuring the shingle spacing, chalk-lining the roof, and holding shingles to the lines. The owner and the remodeler may agree prior to installation that the horizontal line of shingles on the roof of an addition need not line up with those of the existing structure if the floors (and hence, the eaves and ridge) are not to be built on the same plane.
