Shingle Damage Evaluation – Characteristics of Aging – Part 4e
This post is Part 4e of Shingle Damage Evaluation and follows Characteristics of Aging- Part 4d. Part 4 consists of five short lists.
Characteristics of Aging
The following is the last of five lists of characteristics exhibited by aging asphalt shingles:
Shrinkage – Shrinkage is the shortening of the width and/or the depth of the shingle tab as the moisture and the petroleum or other soluble base evaporate from it. Shrinkage is due to the normal aging and weathering of the asphalt materials. Shrinkage is commonly increased by the exposure of the shingle to excessive heat from an inadequately ventilated attic or from a southern exposure.
Wear And Granule Loss At Edges Of Shingle Tabs – Granule loss at the edges of shingles tabs is commonly the result of normal aging and weathering of the asphalt, which degrades the bond strength, and the dislodging of the granules along the edge through abrasion by normal foot traffic.
Defects -Shingle defects appear as irregular shaped, but sometimes circular shaped, areas of granule loss where the asphalt coating or the shingle mat is exposed due to the granules not bonding adequately to the asphalt coating or the asphalt coating not bonding adequately to the fiberglass mat. The inadequate bonding is commonly due to the poor application of the asphalt or the localized contamination of the shingle mat or the asphalt coating that bonds the granules to the shingles during the manufacturing process. Normal aging and weathering loosens the inadequately adhered granules leaving a small area of fiberglass mat or asphalt exposed.
Asphalt shingles can not only exhibit manufacturing defects and/or deterioration from normal or premature aging, but may also exhibit damage from human activity during their installation, regular roof inspection, roof maintainance, and/or intentional or inadvertent vandalism by animals or humans. But before these are discussed it may be helpful to define what constitutes functional hail damage so that the difference between functional hail damage and these other damages may be better understood. Functional hail damage will be discussed in the next installment.