Homeowners may look at their newly installed roof and think, “This doesn’t look like the picture in the brochure.” In fact, variations in the appearance of asphalt shingle roofs are not uncommon, and generally occur for five reasons: color shading, back surfacing transfer, staining, visible asphalt and deviation from installation instructions.
Color shading is usually the result of variations in surface reflectance in different areas of the roof. Even slight differences in shingle texture can make color shading perceptible. This may occur more frequently with black and other dark-colored shingles since only a very small amount of light will reflect from a dark surface.
The variations that cause shading of black or other dark-colored shingles are so slight that they are difficult to detect during the manufacturing process. With white and other light-colored shingles, the total amount of light reflected is considerably greater, resulting in reduced potential for color shading. Shingle manufacturers will often use surface granule blends to reduce the potential for color shading by incorporating a variety of different colors. These blends help reduce shading by making observable differences less noticeable. Color shading typically varies with the time of day, light intensity, and viewing angle.
Back Surfacing Transfer
Fine particles placed on the back side of shingles to keep the shingles from sticking together in the bundle can rub off onto the colored granules on the exposed surface of the shingle. This may cause temporary appearance variation immediately after the shingles are installed. Natural wash from rainfall will eventually remove this loose backing material from the shingle surface.
Staining may occur when shingles are stacked or stored for extended periods. Lighter oils contained in the asphalt coating may seep between and migrate onto neighboring surface granules. Natural weathering generally eliminates this sort of staining over time.
Excessive Surface Asphalt
The shingle manufacturing process includes the step of pressing the surface granules into a hot asphalt coating. This can occasionally result in small amounts of asphalt rising between the surface granules and affecting the appearance in a manner similar to color shading. Natural weathering may reduce the variability depending on the amount of over pressed asphalt.
Deviation from Installation Instructions
Deviations by the roofing contractor from the manufacturer’s printed application instructions may also result in an unanticipated visual patterning. ARMA recommends installers follow manufacturers’ application instructions to avoid patterning.
DISCLAIMER OF LIABILITY: This document was prepared by the Asphalt Roofing Manufacturers Association and is disseminated for informational purposes only. Nothing contained herein is intended to revoke or change the requirements or specifications of the individual roofing material manufacturers or local, state and federal building officials that have jurisdiction in your area. Any question, or inquiry, as to the requirements or specifications of a manufacturer, should be directed to the roofing manufacturer concerned. THE USER IS RESPONSIBLE FOR ASSURING COMPLIANCE WITH ALL APPLICABLE LAWS AND REGULATIONS.
Nothing contained herein shall be interpreted as a warranty by ARMA, either express or implied, including but not limited to the implied warranties of merchantability, fitness for a particular purpose or non-infringement. IN NO EVENT SHALL ARMA BE LIABLE FOR ANY DAMAGES WHATSOEVER, including special, indirect, consequential or incidental damages or damages for loss of profits, revenue, use or data, whether claimed in contract, tort or otherwise. Where exclusion of implied warranties is not allowed, ARMA’s liability shall be limited to the minimum scope and period permitted by law.