Often it can be difficult to know when our roof is failing. Fortunately there are clues to look for.
​The following are signs that may indicate that your roof needs replacing:
​Missing or cracked shingles

• Blistering or peeling paint
• Shingle, sheathing or siding decay
• Leakage in the attic after heavy rains
• Stains on interior walls or ceilings
• High energy bills
• Shingle edges are curled or shingle tabs are cupped
• Bald spots where granules are missing
• Your roof is at least 20 years old; while many shingles today are produced for durability, many factors can accelerate the aging of shingles.

Mold grows indoors when spores in the air land on wet surfaces caused by roof leaks, plumbing problems, ventilation issues, and other moisture sources.  Molds produce allergens and in some cases toxic substances that can cause reactions in people with allergies and asthma.  Mold spores grow when moisture is present so keeping your home dry will prevent a problem in the first place.  After cleaning up mold, if the water problem isn't solved, mold will return.  It is important to accurately assess a mold problem and have clean-up and moisture problems handled professionally.

For more information on Mold, check out the EPA's Guide to Mold, Moisture, and your Home.
Or this article on the dangers of mold from a leaky roof  and this article on mold removal from Water Damage Advisor.