Thirty-year shingles have a life expectancy of thirty years and are therefore covered by the warranty for this life expectancy, and the same concept applies to fifty-year shingles. Also, there is sometimes a correlation between weight, thickness and the life expectancy of the shingles.
Some shingles, such as the three-tab shingles, usually have a life expectancy of approximately twenty-five to thirty years based on their weight. However, there are some shingles that only exist in one thickness and weight, such as the T-lock shingles, but these shingles have been discontinued. Although the life expectancy of some shingles can be deduced by the weight or thickness, different types of shingles with the same thickness might not have the same life expectancy. For example, if a vinyl shingle of one-eighth inch thickness lasts thirty years, it does not necessarily mean that a tile shingle, also of one-eighth thickness, lasts thirty years as well. Additionally, the actual life expectancy of a shingle varies based on the average weather conditions in the area where it is installed.
The manufacturer may be willing to replace shingles that have not exceeded their life expectancy, as long as there are no extraneous factors that have resulted in its destruction, such as improper installation. However, the home owner's insurance may be willing to replace them in the event that the manufacturer does not.