**At the end of the Full Start Period, the labor costs are typically subtracted from the coverage.

***At the end of the Full Start Period, the shingle usage is calculated and subtracted from the shingle cost: To calculate shingle usage, take the total elapsed months from the installation date and divide by the total months of the Limited Warranty. Most standard 'Lifetime' Warranties limit the warranty length to 600 months (50 years) with a 10-year Full Start Period on single family applications, so you would divide by 600. For example, if you have owned your building for 10 years, at the beginning of your 11th year your shingle usage would be: 12 months x 10 years = 120 months. 120 months / 600 months = .20, or 20% shingle usage.

The total months of the Limited Warranty for Heritage Premium or Heritage Vintage shingles is 600 months (50 years) with a 20-year Full Start Period, so you would divide by 600 at the beginning of the 21st year. The total months of the Limited Warranty for Heritage Woodgate and Heritage shingles is 360 months (30 years) with a 15-year Full Start Period, so you would divide by 360 at the beginning of the 16th year.