Composition roofing

Decide whether to repair or replace by following this method on each slope.  Mark off one square (100 sq. ft.). and calculate the total number of tabs. Next, count the damaged tabs.  If at least one out of seven tabs is damaged, the replacement costs will be less than repair.

Hail damage. To find out if a a tab is broken feel the underside.  If it is damaged, it must be replaced.  If it is not damaged but the mineral granules have been knocked off, consider an allowance for loss of life expectancy.

Hail damage is evidenced by fresh dents on built-up roofing. Hail does not cause bubles, wrinkling or alligatoring.  Bubbles are attributable to entrapped moisture.  Wrinkling is caused by shrinkage and expansion of sheathing.  Alligatoring is caused by evaporation of oils.

Wind damage. Check for wind damage at the line formed by the overlapping shingle. Wind will often raise the tabs, braking them at this point.

If a windstorm blew gravel off of a built-up roof the gravel should be replace, but does not need to be hot-mopped into place.

Wood roofing inspection 

Splitting of shingles expectedly occurs as shingles weather.  Splits will widen with age.  What may appear as a new split may be an old split that has becom more obvious.

Any splitting caused by a hail storm can be detected shortly after the storm, but only after the roof is dry.

Splitting caused by hail will manifest soon after the storm.  Note: Hail caused dents do not progress to splitting.

Fractured shingles should be replaced.  

Spots that appear decayed due to denting do not require replacement.