Shingle Damage Evaluation – Other Damages That May Be Mistaken for Hail Damage – Part 6c

Posted by in Shingles | August 06, 2012

This post is Part 6c of Shingle Damage Evaluation and follows Other Damages That May Be Mistaken for Hail Damage – Part 6b.

Other Damages That May Be Mistaken For Hail Damage – Part 6, is comprised of four posts that discuss the causes and characteristics of damages that are commonly inflicted on shingles by other means, such as human or animal activities.  These other damages may be mistaken for hail damage by someone poorly trained and/or the inadequately experienced.

Following is the third list of four damages effected by other means:

  1. Mechanical Damage – Mechanical damage to a shingle is evidenced by a small area of granules being pushed into the asphalt and/or the mat.  The small area usually exhibits the shape of a tool or other hard object.  Inadvertent or accidental mechanical damage is evidenced by the very small number of these and/or their clustering in areas occupied during maintenance.  Mechanical damage may be distinguished from hail impact damage by the shape of the damage, the depth of the damage, the embedding of the granules, the crushing of the granules, the scratches on the granules or the asphalt, the impression left in the asphalt, and the pattern and/or frequency of the damage.  Intentional mechanical damage to mimic hail damage will be discussed in a later post.
mech damage from tool

SDE-46 Mechanical damage from a tool. Note tool marks in asphalt.


double hit mechanical damage

SDE-47 Twin mechanical damage marks from impact by a tool.

  1. Raised Nail Heads And Staples – The small areas of granule loss and/or fracturing of the shingle mat over a nail head or a roofing staple are due to the increased exposure of the asphalt to the sunlight by the stretching of the shingle over the raised nail head or the roofing staple.  The raised condition of the nails and/or the staples on the roof is the result of the backing out of the nails or the staples in the roof deck and/or the under-driving of the nails or staples or the driving of the nails or staples at an angle during the installation of the shingles.  The backing out of the nails or the staples is the result of the cyclical shrinking and swelling of the roof deck from seasonal moisture variations over the years.  The severity of the shrinking and swelling of the roof deck due to the seasonal moisture variations is commonly increased by inadequate ventilation of the attic spaces.  Granule loss and/or fracturing of the mat due to raised nail heads may be distinuguished from hail damage by the relatively uniform pattern of their location, which matches the expected pattern of the nailing, the raised surface at the fracture in lieu of the sunken surface at the fracture, and/or by lifting the tab to identify the cause of the raised surface in the tab.
shingle tab lifted by raised nail head

SDE-48 Shingle tab lifted by raised nail head.

mat fracture over raised nail head

SDE-49 Shingle mat fractured and raised. See next photo.

mat was fractured over raised nail head

SDE-50 Shingle mat fractured and raised over raised nail head.

  1. Ridging  – Ridging is the pronounced lifting of the shingles over a raised edge of the roof deck.  It commonly appears as a straight line and outlines the sheets of roof deck.
pronounced ridging

SDE-51 Pronounced ridging in roof.


subtle ridging

SDE-52 Subtle ridging causes line of tabs to be lifted across roof surface.

  1. Vermin Damage – Vermin damage is characterized by a relatively small, broken corner or edge of a tab.  It often exhibits claw marks, jagged fracture surface, and/or feathered edges at the fracture.   Vermin damage is commonly due to various animals clawing at seeds or other foods lodged under the edge of a tab.  It may also appear where animals have attempted to gain access through the roof into the building.
clawing from animal

SDE–53 Clawing damage at edge of tab from animal.