Wind v. mechanically induced damage in roof evaluations

Wind v. mechanically induced damage in roof evaluations 
Top 7 tips of insurance claims fraud  
by Daniel Joita P.E. – Senior Forensic Engineer

With the increased number of insurance claims, especially during recent storms/hurricane season, there’s been an increasing trend of mechanically induced damage to roofing surfaces. Many claims in the roofing industry call for a detailed examination as the amount of altered evidence becomes more obvious.

Roofing contractors often offer to help the homeowners with their claim by providing a free inspection. By doing so, some contractors will sometimes generate more damage by inspection activities rather than the wind damage from a storm.

Asphalt shingles

Most residential homes have asphalt shingles – also known as composition roofing or laminated shingles. Asphalt shingles make up approximately 80% of the residential roofing market in the U.S. and are commonly used in the Southeast. Shingles are water shedding and not water proof, meaning they can be used for slopes over 4:12. Usage of shingles on roof slopes from 2:12 – 4:12 is only permitted in certain locations and with special provisions regarding the underlayment.

One advantage is that shingle roofs can be reapplied over existing composition shingles (up to three layers in most states) without the need to strip off all the previous layers. However, some roofs cannot take the weight of all three layers of shingles without significant sagging.

Weathering /anomalies
Shingles can deteriorate with age. In the hotter climates asphalt shingles tend to deteriorate more quickly than in cold climates and similarly the slope of the roof with the greatest sun exposure is likely to deteriorate first. Some of the most common weathering effects found in exposed shingles are curling, craze cracks, blisters, algae and granular loss. At times manufacturing issues such as inconsistencies in the shingles and bundle variations may be encountered. A typical manufactured shingle that has been discontinued is represented by the Atlas – Chalet brand, famous for the cracks and blisters occurring on the second granule layer / appliqué.

Wind damage

When wind interacts with a building, both positive and negative (i.e., suction) pressures can occur simultaneously. Wind pressures do vary along the various roof slopes and relative uplift pressures are a function of roof geometry, roof slope, location on roof.
Here are the top 7 tips when assessing wind damage claims:
1. Distribution of damage on all slopes. Typically, the windward side of the house during a storm event receives the highest wind speeds and thus shingles on the windward slope are more susceptible to wind damage.
2. Concentration of damage on fields. Sharp edges and discontinuities in building geometry, act as wind forces concentrators. Wall corners, gables, eaves, hips and ridges will typically receive the highest wind forces.
3. Irregular arched or diagonal creases. Continuous back and forth lifting of the shingle will create a crease on the shingle surface. Once a crease is formed in the surface of the tab this location becomes a weakened hinge point. Wind damage to a tab will not result in a double crease.
4. Diagonal or partial creases / tears near the shingle corners or edges. Shingle tabs exhibiting partial creases at the edges, or diagonal creases at the tab corners is a condition not consistent with wind damage but rather with manual lifting of a tab.
5. Patterns in damage. Wind damage to a roof typically does not occur in patterns but is random in nature affecting areas of the roof that are more susceptible to elevated wind speed.
6. Presence of shingles repaired with roofing cement. Repaired shingles should not be susceptible to wind effects since they have increased resistance compared to regular shingles.
7. Reported wind speeds. Weather reports are available for the public and should contain accurate information regarding the expected maximum wind speeds at a certain location. Any inconsistencies between reported wind speeds and observed roof damage should be addressed.