Cracked, curling or buckling shingles
These problems could be signs that your home has inadequate roof ventilation or that your shingles have reached the end of their useful lifespan.

Dark or dirty-looking spots
Dark or dirty-looking spots could be caused by granule loss on the shingles due to aging, or from algae or fungus growth, an indication of other, unseen problems with your roof.

Drastic increases in energy costs
Increases in energy costs could be a sign that your home has inadequate roof ventilation, causing your heating or cooling system to run excessively.

Leaks after heavy rain
Leaks following rain could mean that you have deteriorated flashing somewhere on the roof, preventing your home from being sealed properly. Leaks could also indicate the shingle underlayment is damaged or inadequate.

Leaks after driving snow
Leaks following a heavy snow could be caused by inadequate or improperly-installed shingle underlayment allowing water from ice dams to leak into the attic. Clogged vents, poorly-installed gutters, or an improper balance of static and soffit vents can also lead to post-snow leaks.

Mildew growth or water stains on interior ceilings
These problems may indicate that your home has inadequate roof ventilation or that there is faulty shingle underlayment that is causing a leak.

Shingles or siding decay
Decay of shingles or siding could be a sign that your home has inadequate roof ventilation.