The CertainTeed warranty covers defects. Maintenance covers the rest.

• Inadequate ventilation. If the deck isn't adequately ventilated, as CertainTeed determines, coverage drops to 10 years without SureStart protection.
• Impact, foot traffic and falling objects, including wind-blown objects, tools and equipment.
• Ice backup and ice damming, to the shingles, the deck or the home.
• Misuse, abuse or neglect, and stains from algae (other than blue-green algae), moss, lichen, mold, paints and chemicals.

The warranty also warns that copper released by algae-resistant granules can react with aluminum gutters and cause severe corrosion.

None of that is a manufacturing defect. Most of it builds slowly, out of sight from the ground, and the homeowner finds out when something leaks.

• A professional inspection at least once a year. CertainTeed says twice a year is ideal, in spring and fall, and again after major storms.
• Homeowners stay off the roof. CertainTeed says to look from the ground or a ladder, never by walking on it, and to hire a roofing professional for a thorough assessment.
• Professionals handle the growth. For algae or moss, CertainTeed recommends a professional apply a cleaning agent and brush gently, and it warns that a power washer can easily dislodge granules.
• After storms, document and call a contractor. Take photos and notes, have exposed areas covered, and schedule a professional inspection.