Many types of roofing permit the application of a coating or rejuvenator for a variety of reasons, such as increasing solar reflectivity, resisting biological growth, improving impact resistance, or increasing roof life. However, ARMA strongly advises against the field application of any type of coatings or rejuvenators over installed asphalt shingles.
There are many types and formulations of roof coatings and rejuvenators, so it is always important to consult the shingle manufacturer before proceeding with any type of application on asphalt shingles. Many asphalt shingle manufacturers specifically do not recommend installing field treatments on their shingles. Additionally, state or local building codes may prohibit this practice, as the field-applied coatings or rejuvenators may negatively impact the performance characteristics (including the fire classification, algae resistance, impact resistance, etc.) of the roof assembly.
Some problems reported after asphalt shingle roofs have been field-treated include shrinkage of the coating material, which may result in unsightly curling and/or cupping of the shingles or loosening of the granule surfacing of the asphalt shingles. In addition, non-permeable roof coating materials may create a vapor-retarding layer by sealing the voids around and between the shingles. If this occurs, it may contribute to moisture accumulation within the roofing system.
It has been suggested by some that the use of field-applied coatings or rejuvenators over existing asphalt shingles will produce overriding benefits to the homeowner, such as longer roof life, energy-use reduction, or remediation of small roof leaks. There is limited available documentation showing the extent to which these materials are applied to asphalt shingles and whether they provide any of these benefits, but the risks and concerns mentioned above remain very real. Further, many such treatments need regular maintenance reapplications to provide a consistent appearance.
In addition to coatings, there are also liquid-applied materials marketed as “rejuvenators” for asphalt shingle roofs. These materials are typically sprayed or rolled on an existing asphalt shingle roof that has been in service for several years and may be displaying normal signs of aging. As is the case with other coatings, many asphalt shingle manufacturers specifically recommend against applying a rejuvenator material on their shingles.
In summary, the application of a coating or rejuvenator may be detrimental to asphalt shingles. Be sure to:
- Check with the asphalt shingle manufacturer to determine if a specific field treatment is acceptable for use with their roofing shingles.
- Check with the local building and zoning department and, if appropriate, your homeowner’s association to determine whether this application is allowed.
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.
