• Exposure... Either long-term exposure to the elements (sun, water, freeze-thaw) or shorter-term exposure to damaging air pollutants, and chemicals

• Structural Movement... Such as building settlement or expansion/contraction not accommodated by the roofing system
• Biological Growth... Such as vegetation in areas of standing water or algae
• Not Fixing Problems Promptly... 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
• Forgetting About Maintenance... This is perhaps the biggest cause of premature roof failure
• Change In The Use Of The Building... e.g., an increase in the interior relative humidity of a building can cause severe condensation problems within the roofing system

 - Dick Fricklas, REIE