Roofs leak for many reasons. First, you must identify the cause of the roof leak. A universal repair material (like Topps Polyprene®) will fix most roof problem areas on ANY roof type.
Moisture is a roof’s (and a building owner's) biggest enemy. Quality roof repair compounds, together with roof waterproofing coatings, like Topps Seal®, are the best solution to fix a roof leak. It can also be the most economical approach to preventing new ones when done on a timely basis. The National Roofing Contractors Association recommends inspecting all roofs twice each year, once after the hottest weather and again after the coldest weather. It is these weather cycles that induce the most thermal stresses on roofs and manifest the greatest damage. Roofs should also be inspected after any major weather event, such as high winds or hail. (from The Importance Of Roof Maintenance By Edis T. Oliver - July 2008 Facility.net)
"Eventually, no matter what type of roof, the ravages of freeze/thaw cycles, rain, summer sun, blustery winds and all the rest of Nature’s arsenal take their toll. Leaks develop in all roofs over time, causing U.S. building owners to spend more than $12 billion annually on repairing, recovering or re-roofing...Moisture degrades the mechanical integrity of the insulation system, corrodes metal components such as fasteners and metal decks and adds excessive weight to the roofing system. Wet roofing also increases energy losses up to 70 percent because wet insulation loses its thermal resistance.” - ‘Rerooﬁng: How Wet Is Too Wet?’, Rita Tatum, Building Operating Management, February 2001