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Mechanical Damage to Asphalt Shingles - cuts, punctures, tears, granule loss InspectAPedia®  -     Photo guide to mechanically-damaged roof shingles & mineral granule loss Shingle granule loss due to foot traffic or other shingle damage; roof damage during inspection in hot weather? Shingle damage due to cuts, tears, misaligned roofing staples, or application errors Types of roof shingle stains, causes, cures, prevention Case study examines causes of damaged roof shingles and granule loss

This document discusses mechanical damage to shingles from a variety of causes: foot traffic, tears, punctures, tool cuts, or damage during shingle installation. The results of mechanical damage to asphalt shingles includes mineral granule loss from the shingles, leaks, or simply shorter roof life. Other common asphalt shingle failure factors discussed in this article series include improper storage and handling of the asphalt shingles before installation, improper nailing, improper flashing (which pertains to any roofing material), and defective asphalt shingle product material leading to thermal splitting, cracking, blistering, staining, and in some cases curling or cupping shingles.

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Case Study of Damaged Asphalt Roof Shingles

Here we present a series of photographs of asphalt roof damage. A professional investigator documented these conditions and joined in a discussion of the apparent cause of damage shown in each photo. All of these pictures were taken on the North slope of an asphalt shingle Firehalt brand roof.

A windstorm adjuster for TWIA (Texas) inspected an insured's roof with a large amount of granular loss. The roof is in these photos is 10/12 pitch (hip with build ups) and was 11 years old at the time of inspection. The roof is vented by turtle vents (4) and (1) turbine vent only (no ridge vent). The shingles are Firehalt Brand (Certain Teed®) - 30 year shingles. In our opinion the damage was not, however, related to the brand. Roof consultants, manufacturers, suppliers, and building inspectors are invited to Contact Us to offer further diagnostic comments about this case.

Conclusions About These Contributors to Asphalt Shingle Damage & Mineral Granule Loss on This Roof

1. Primarily, questionable or perhaps even poor workmanship, use of staples, mis-located, staples askew, high raised-corner staples, mis-stapled on top of shingles, foot traffic, mechanical damage, possibly excessive bending in cold weather at the hip/ridge appear to be the problems on this roof. We also saw some minor mis-nailing or inadequate nailing leading to a single blow off at the roof hip.
2. Secondarily: a few of the cuts and damage could be defective product - see CRACKS in FIBERGLASS SHINGLES. At least one cut was made by a tool or implement.
3. Weather does not appear to be a root cause of this roof damage, though once a shingle has been worn by walking or mechanical damage the exposure of the shingle substrate accelerates wear and granule loss.
4. We would not characterize the prime problem of this roof as "granule loss" which was the original owner's concern. GRANULE LOSS from SHINGLES provides more details.

In our opinion the roof damage was not, however, related to the brand. Roof consultants, manufacturers, suppliers, and building inspectors are invited to Contact Us to offer further diagnostic comments about this case.

Walking on an Asphalt Shingle or Roll Roofing Roof can Cause Damage to the Roof

Walking on a roof can damage shingles in several conditions.

Asphalt Shingle Roof Damage from Walking on Fragile Roof Surface

Granule loss or actual shingle damage may occur on a roof being walked-on: walking on any asphalt shingle roof loosens some of the mineral granules from their attachment embedded in the asphalt used to impregnate and coat the shingle.

Walking on shingles that are brittle, cupped, curled, can damage them at any time, perhaps moreso if the inspector steps on a raised, curled, or otherwise damaged portion of the shingle, or if the asphalt shingles are simply old, brittle, and fragile, even if flat.

We investigated a complaint against a home inspector charged with damaging a roof that we learned he had been smart enough to stay off of - inspecting from the roof edge by ladder. But a contractor, called to bid on roofing repairs, stomped around inspecting the roof to make his repair bid. The result was conversion from a roof that needed replacement soon to one that needed immediate replacement. We could virtually see the footprints of the contractor, in a trail of broken shingles across the roof.

Asphalt Shingle Roof Damage during Other Repair Work

On roof repair work of other components, for example around a chimney, involving standing, moving, turning, placing repair materials on the roof surface without first protecting that surface from damage.

If there is a lot of roof traffic, such as when work is being done on a chimney, you may see "bald" areas of shingles with lost granules where people have been walking. This is damage caused by workers and is not a product defect.

Walking on fragile roof shingles. See CUPPING ASPHALT SHINGLES and CURLING ASPHALT SHINGLES.

Roof Damage from Walking on very Hot, soft Asphalt Roofing

We think it's subjective, and we don't have a specific number, but the variables underlying roof damage during an on-roof walking inspection include:

• outdoor air temperature at the time of the roof inspection
• sun exposure on different roof slopes - a shaded slope may be cooler and safe to walk-on even on a hot day
• number of hours the roof has been exposed at various temperatures - longer roof exposure to sun and high temperature ona given day, walking on a roof in the last half of a very hot day, for example, is more likely to lead to damage
• the nature of the foot traffic - walking carefully vs. standing in one place and spinning on your heels - the latter will certainly damage a hot soft asphalt shingle or roll roofing.

Alone no single number answers the questions raised by these factors. But certainly we've both seen damage to roofs when walked onduring a hot day - when someone was careless.

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ASPHALT ROOF SHINGLES
  SHINGLE LIFE / WEAR FACTORS
  ASPHALT SHINGLE FAILURE TYPES
  ALGAE, FUNGUS, LICHENS, MOSS on SHINGLES
  BLISTERS on ASPHALT SHINGLES
  CRACKS in FIBERGLASS SHINGLES
  CUPPING ASPHALT SHINGLES
  CURLING ASPHALT SHINGLES
  FISHMOUTHING ASPHALT SHINGLES
  GRANULE LOSS from SHINGLES
  HAIL DAMAGED SHINGLES
  LADDERING & STAIR STEPPING SHINGLES
  MECHANICAL DAMAGE of SHINGLES
    ROOF DAMAGE CASE STUDY
    ROOF DAMAGE DUE TO INSPECTION
  MOSS & LICHENS on SHINGLES
  ORGANIC FELT SHINGLE DEFECTS
  SPLICE DEFECTS on ASPHALT SHINGLES
  STAINS on ROOF SHINGLES
  WHAT ARE ASPHALT SHINGLES

• Randy LeBlanc, a Windstorm Adjuster for TWIA (Texas), provided photographs and assisted in technical assessment of this material 4/12/09.
• Charlie Gallagher is a professional home inspector in Lawton, OK and can be contacted at CAGFISHING@aol.com

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