Roof Shingles

What Are Roof Shingles

Roof shingles are overlapping flat pieces of material installed in courses from the eave to the ridge to shed water and protect the underlying roof deck. In North America, asphalt shingles dominate the residential market, covering roughly 75 to 80 percent of homes. Asphalt shingles use a fiberglass mat base coated with asphalt and surfaced with ceramic-coated granules that provide UV protection, fire resistance, and color. Other shingle materials include metal (stamped steel or aluminum panels that mimic traditional shingle shapes), composite (engineered polymers designed to replicate slate or wood), and rubber (made from recycled tires or EPDM). Each material offers different performance, weight, and cost profiles, and each has distinct failure modes that matter for insurance claims and Xactimate estimates.

How Roof Shingles Are Installed

Shingle installation follows a specific layering sequence. The roof deck is covered with underlayment (synthetic felt or self-adhering membrane at vulnerable areas). Drip edge is installed along the eaves and rakes. A starter strip course is laid along the eave with the adhesive strip positioned to seal the first row of shingles. Field shingles are then installed in staggered courses from the eave upward, with each course overlapping the one below it. Nailing patterns vary by manufacturer but typically require four to six nails per shingle in a specific nailing zone. Hip and ridge cap shingles finish the peaks. Proper nailing is the single most important installation variable for wind resistance. High-nailed shingles (nails placed above the manufacturer's nailing line) are significantly more vulnerable to wind blow-off.

Common Shingle Problems

The most visible shingle problem is granule loss. Hail impacts knock granules off the mat surface, and normal weathering causes gradual granule erosion over time. Once the mat is exposed, UV light accelerates asphalt degradation and the shingle becomes brittle. Wind damage ranges from minor tab lifting to full shingle blow-off, depending on wind speed and nailing quality. Blistering occurs when moisture trapped in the asphalt mat expands during heat cycles, creating bubble-like raised spots. In humid climates, algae (Gloeocapsa magma) causes dark streaks that are cosmetic but can affect property value. Thermal cracking appears as splits in older shingles that have lost flexibility.

Roof Shingles and Insurance Claims

Shingle damage is the most common residential roofing insurance claim. Adjusters differentiate storm damage from wear and tear by examining damage patterns. Hail damage produces random impact marks with granule displacement and sometimes mat fractures. Wind damage follows directional patterns, with the most damage on the windward slopes and at edges, ridges, and hips. Proper documentation includes close-up photos of individual damaged shingles showing the damage mechanism, wide shots showing the pattern across the roof, and measurements of the affected area. Xactimate line items for shingles are priced per square (100 square feet) and vary by shingle type, weight class, and manufacturer product line. Matching existing undamaged shingles in color and profile is a common supplement item when the original product has been discontinued.