Weather and Aging Asphalt Shingle Damage Examples

15 August 2017

We're almost through August and, after a record breaking high temperature July here in Utah, our Operations Manager, Michele Wolle, put together some great information on what extreme temperatures, weather and aging can do to asphalt shingles! While many of our contractors have seen most, if not all of these (some even on the same roof), it's great information for home owners who are making the decision on replacing or repairing their current roofing shingles!

The following are a few signs and descriptions of aging and weathered shingles.

Blistering - Bubbles or pimples in roofing materials. Sometimes during the manufacturing process moisture can get trapped within the shingle itself. If the shingles on a roof have trapped moisture, they are highly likely to start blistering. Why? Because as the sun heats up the shingles the trapped moisture heats up as well and can cause blisters to rise up on the shingle. Roofs that do not have an adequate ventilation system in place can get too hot for shingles. If a roof that is poorly ventilated gets too hot, the shingles can blister because of the intense heat.

Bubble shingles









Curling And Cupping - Curling and cupping are the upward lifting at the corners and edges of the shingles. Curling and cupping occur as a result of the swelling of the underside of the shingle relative to the top of the shingle and/or the shrinkage of the top surface relative to the underside of the shingle. The swelling of the underside of the shingle is commonly due to the migration of excessive amounts of airborne moisture from the attic spaces through the roof deck and into the bottom surface of the shingle. The shrinkage of the top surface is commonly due to normal aging and weathering of the shingle over the years.

 Curling shingles









Craze (Map) Cracking - Craze or map cracking of shingles appears as a pattern of roadways similar to a map. Crazed cracking is the result of the normal deterioration of the asphalt coating of the shingles from aging over the years. When the asphalt material dries, shrinks, and weathers from normal exposure to water and sunlight it is randomly stretched. The random stretching of the asphalt causes it to crack in a random pattern.

 Craze or Map Cracking









Embrittlement – Embrittlement is the hardening of the soft asphalt and the shingle mat materials over the years such that the shingle becomes brittle and is susceptible to shattering, cracking and breakage. Embrittlement occurs as a result of the normal aging and weathering of the shingles over the years; however, it is accelerated by the exposure of the shingle to excessive heat from a poorly ventilated attic.



Flaking – Flaking is the delamination of the upper layer of the asphalt which bonds the granules to the lower layer of asphalt that saturated the organic shingle mat. Flaking is commonly due to the drying and degrading of the asphalt over the years and the differential movement between the bond coating and the saturated coating caused by the repeated shrinkage and swelling from moisture variations and/or expansion and contraction from thermal variations. When flaking is somewhat circular in shape, it is sometimes mistaken for hail damage. However, closer visual and tactile examination disclose that the flakes do not exhibit a fracture or an indentation in the mat (as will be discussed later), but a well-defined edge of the remaining second asphalt coating applied to bond the granules.











Fractures And Splitting – Vertical, horizontal and/or diagonal fractures or splits in the shingles are due to the thermal expansion or contraction of the shingles and/or the roof deck in combination with excessive restraint of the shingle strip. Excessive restraint of the shingle strips is commonly due to an inflexible tab sealant. The combination of the restraint of the shingles by the nails and the sealant with the expansion/contraction of the shingles or the roof deck causes the shingles to be stretched: this is called tension. When the tension stresses from the stretching exceed the strength of the shingle, it fractures or splits.

 Fractures and Splitting