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

Posted by in Shingles | August 13, 2012

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

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 last list of three damages effected by other means:

  1. Scuffing  – Scuffing is where granules have been abraded by foot traffic or by contact with another abrasive object.  Scuffing is often accompanied by a drag mark where the scuffing appears to fade in one direction, the direction the object approached or left the shingle surface. Scuffing is more common on steep slopes where more friction forces are inadvertently applied to avoid sliding off the roof.  Scuffing may be distinguished from hail impact damage by the shape, the shallow scratch marks on the granules of the asphalt, and/or the lack of being accompanied by a fracture, an indentation, or a soft spot in the shingle mat.


scuffing of shingles

SDE-54 Granule loss due to scuffing of shingles.


scuffing 3

SDE-55 Granule loss due to scuffing of shingle. 


  1. Dollop (Spot) Of Asphalt – Random dollops of excessive asphalt on the surface of the shingles are due to the application of an excessive amount of asphalt during the manufacturing process or the splattering of asphalt on the shingle during repair work. The dollops of excessive asphalt do not affect the function of the shingle.
dollop of asphalt

SDE-56 Dollop of asphalt on shingle surface.

  1. Staining And Streaks – The blotches and streaking pattern of staining on the surface of the shingles are a result of biological growth, usually algae.  Biological growth is more common on the shaded or slow drying areas of a roof especially the north slopes where the shingles remain damp longer due to the reduced exposure to the warmth of direct sunlight.  Biological growth is more common on shingles manufactured from the late 1980s to the late 1990s when the materials used by some manufacturers promoted the growth of algae.  A close examination often discloses the biological growth on and around the granules.
streaking stains

SDE-57 Streaking staining from biological growth.

  1. Unsealed Shingle Tabs – The unsealing of the shingle tab from the underlying shingle strip due to a failure of the bond between the sealant and the underside of the overlying shingle tab is called an adhesive failure.  The unsealing of the shingle tab due to a fracture within the asphalt coating of the mat or within the sealant is called a cohesive failure.  Adhesive failures are predominantly due to the failure of the sealant where the unsealed shingles generally appear in the field of the roof rather than at the locations of high wind uplift pressures such as at the rakes, at the eaves, at the ridge, at the hips of the roof; exhibit a diagonal or vertical line pattern located over the joints between two adjacent shingle strips; show little residue of the sealant on the underside of the shingle; exhibit weathered, discolored, and/or dirt a covered sealant; and/or are coincident with high, overdriven, angled, or mislocated nailing which has lifted the shingle from the sealant.  Additionally, unsealing commonly progresses over time due to repeated differential movement between the overlying and underlying shingle strips.  It is an excepted industry practice to re-seal unsealed or poorly sealed tabs by hand with an asphaltic roofing cement approved by the shingle manufacture.  This is a regular maintenance issue to reduce the risk of damage from winds because unsealed or poorly sealed tabs are more vulnerable to lifting by normal and expected winds.  Impact from hail stones is not capable of loosening a properly sealed shingle tab.


unsealed shingle tabs lifted

SDE-58 Unsealed tabs exhibit slight lifting.


longtime unsealed tab

SDE-59 Dirt covered portions of sealant indicate tab has been unsealing over an extended period time: cohesive failure (left) is recent.


The next post will discuss the characteristics of damages that are inflicted with the intent to mimic hail damage, that is, intentional damage.