If you think you might need a new roof, the first place to check isn't your home exterior—it's your attic. So arm yourself with a flashlight and climb up under the eaves. Look for beams of light coming through the top of the house or stains and streaks, which signal a leaky roof. The same is true for commercial roofing and in many cases a commercial roof can see above a T-Bar ceiling or in a warehouse.
Review your maintenance records to see how long ago the roof was replaced or re-shingled. Keeping a maintenance log of annual inspections and repairs and knowing when a roof was installed (and what it's made of) offers insight into how much life it has left. For instance, a typical low slope commercial roof has an expected life of 20-30 Years while an asphalt shingle roof lasts 20 to 70 years. When a roof installed over an existing layer of shingles should be replaced after 20 years.
Keep an eye on your rooftop to make sure it’s kept clean and free of debris and gutters are clear especially after heavy storms or expected heavy storms. Shingles should lie flat against the roof; if you find patches that are cracked, damaged, or buckling, then repairs are in order. While you're at it, check the gutters and downspouts for shingle granules—a roof that is losing a lot of granules may be at the end of its useful life and this is true for both commercial & residential roofing systems.
Be sure to inspect flashing around vents, skylights, and chimneys. This adds protection to theseams of the roof from rain and weather.
Examine these points and make sure there are no cracks or breaks, which could lead to leaks. In older homes and businesses, flashing is often made of roof cement or tar, but it's a good idea to upgrade to a metal flashing system for added durability.
A droopy, sagging roof is one that surely needs replacing before further damage occurs to your home or business. Check the surface for signs of trapped moisture, rotting boards, or sagging spots—especially at the lowest points in the roof.