ARMA strongly advises against the application of any type of field-applied coating over installed asphalt shingles. There are many types and formulations of roof coatings so it is important to always consult the shingle manufacturer before proceeding with any type of coating. Be aware that some asphalt shingle manufacturers specifically disallow field coating of their shingles. Additionally, state or local building codes may not approve this practice as the field applied coatings may change the performance characteristics, including the fire classification, of the roof assembly.
Problems reported after asphalt shingle roofs have been field coated include shrinking of the coating, 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 coatings may create a vapor retarding layer by sealing the voids around and between the shingles. If this occurs, it increases the possibility of rotting of the roof deck caused by moisture accumulation in the attic space.
It has been suggested by some that the use of field applied coatings over existing asphalt shingles will produce overriding benefits to the home owner — such as longer roof life, energy-use reduction, or remediation of small roof leaks. There is little or no available documentation showing the extent to which the field coating of asphalt shingles provides any of these benefits, but the risks and concerns mentioned above remain very real.
Before considering coating of installed asphalt roof shingles, be sure to:
• Obtain approval from the asphalt shingle manufacturer before proceeding with a specific roof coating.
• 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.