It is possible for a roof to naturally reach the end of its useful life without experiencing a roof failure, then it just looks outdated and worn, and you are doing preventive service on your home, and however, if you delay replacing an outdated roof, it could result in more serious concerns down the road. You should therefore be on the lookout for the warning signs so that you give yourself plenty of time to add the project to your to-do list. If your shingle edges are curled or if the tabs on the shingles are cupped, it may be time to substitute your roof. Your roof is reaching the end of its lifespan if your shingles are cracked and there are bald spots on the roof where the granules have fallen out, but when your roof is at least 20 years old, it is reaching the end of its useful life. In spite of the fact that several of today’s shingles are designed to be durable, the aging process can be accelerated by a number of factors. Having an unventilated roof, for instance, will disadvantagely impact your shingles if you are not properly ventilating it. Homes built around the same time period can experience the same types of weather conditions and you may also find your roof is nearing the end of its useful life as well, then roof decks can become stained with dark streaks caused by airborne algae! Despite the fact that this may not necessarily harm the roof shingles, it is unlikely to look good, but there is a occasion that some types of mold can grow on roof surfaces that do not gain enough sunlight, especially in cool, moist weather conditionss, however mold growth can be more than merely an aesthetic problem. Moss holds moisture against the roof surface and in freezing conditions, over time, it can lead to destruction to the granules on top of the shinglesâ€¦ Even though you can brush off the moss, it will still grow back if you do not take care not to destruction the shingle surface. It may be in your best interest to contact a professional roofing contractor.