Leaks usually occur long before they are visible. One way to tell if a roof is leaking is a fast look at an energy bill. Assuming that each month’s payment is within a few dollars of each other, then suddenly starts increasing each month without more energy usage, there is a good chance a problem has developed.
If energy bills are unable to show any trend, another way to test roof harmony is a trip to the attic. Water leaks from rain and snow are usually unable to be seen in an actual room for some time, until it is too late to patch the leak; therefore requiring more time and money to fix the rotted drywall in the ceiling and walls. Visiting the attic is the quickest way to spot any signs of leaks. Insulation will be matted and discolored, in some cases even still wet. Beams and trusses of the actual roof will also be water stained. If it has happened very recently, it will still be moist.
Spotting and following these signs usually helps pinpoint the exact origin of where the damage has occurred. If access to the attic is not possible, the next step in the process is to venture up onto the roof itself and look at it from above. Immediate signs of damage include visible nails, torn or missing shingles, shingles that appear to be “bubbled up” or not flat, or moist or wet patches on or under shingles.
Metal and tin roofs are a little trickier to determine the existence of damage, but still entirely possible. Signs of metal roofing damage would be sheet metal screws missing or backed out, cracked rubber seals around sheet metal screws, large dents where rain could puddle, gaps between seams of metal, and missing or detached weather stripping between seams as well as the ridge. Any holes that can be seen will leak with a metal roof, even if they are tiny pinholes. Regular inspection of roofs and attics are highly recommended to ensure the roof is sound. This will prevent the problem from escalating into time-consuming, costly repairs later on.