Either long-term exposure to the elements (sun, water, freeze-thaw) or short-term exposure to damaging air pollutants and chemicals.
Such as building settlement or expansion/contraction not accommodated by the roofing system
Such as vegetation in areas of standing water or algae
These can add up to a much shorter roof life – e.g., if a small problem is not repaired, then a large amount of insulation can be damaged
This is perhaps the single biggest cause of premature roof failure.
e.g., an increase in the interior relative humidity of a building can cause severe condensation problems within a roofing system