Essentials

Many spray polyurethane foam- (SPF-) based roof systems are coated with elastomeric coatings that generally require some amount of yearly maintenance and recoating about every 10 years to 15 years.

NRCA is aware of instances when SPF roofing contractors have been involved in recoating projects where there has been confusion regarding the interpretation of building code requirements, specifically whether a recoating project can be construed as a reroofing project.

The 2003 International Building Code (IBC) defines reroofing as "the process of recovering or replacing an existing roof covering" and roof covering as "the covering applied to the roof deck for weather resistance, fire classification or appearance."

One of the building code's requirements for determining whether a re-cover roof system can be installed is whether the existing roof has two or more applications of any type of roof covering.

Because SPF commonly is used in re-cover applications, an SPF-based roof system often is the second roof system in place. And because the code doesn't allow a third roof system to be installed, there are situations where recoating an SPF-based roof system has been construed to be reroofing. Therefore, the recoating project is not allowed without removal of the existing roof systems. This can result in a generally unnecessary tear-off and disposal of roofing materials.

NRCA's position

Application of an elastomeric coating on an existing SPF-based roof system is not equivalent to installation of an additional roof system; rather, it is considered a maintenance item.

Simply put, when an SPF-based roof system is recoated, a new coating is installed where the existing coating has deteriorated or worn away. This is a unique property of SPF-based roof systems—the ability to be sustained by application of new coatings. The reapplication of a coating is a necessary part of an ongoing maintenance and repair program that optimizes the service life of an SPF-based roof system.

The NRCA Roofing and Waterproofing Manual, Fifth Edition, states: "Before proceeding with a recoat, an extensive evaluation of the existing SPF roof system should be made. As with other roof systems, this must be done by professionals and, at a minimum, should consider structure, decks, fasteners, SPF and elastomeric coatings. These all must be in acceptable condition. Building codes and energy codes should be consulted to see whether requirements are in place that may affect the recoat application. Typically, a recoat is considered maintenance and repair to an existing roof system. (If new foam and coating will be added, it may be considered to be installation of a new roof system.) Installation of small amounts of new foam to correct drainage or other deficiencies still would be considered repairs. This also would hold true for areas where a roof system would be scarified and refoamed before coating application."

In addition, the manual states, "Recoats may use elastomeric coatings or membrane surfacings."

Part of the misinterpretation of building code requirements is related to the purposes of elastomeric coatings.

NRCA's manual states coatings "provide the long-term weather-proofing characteristics of SPF-based roof systems. SPF requires a protective surfacing to protect it from the sun's ultraviolet rays and mechanical damage, to prevent premature weathering or degradation, and to achieve a fire rating for the roof assembly. Elastomeric coatings, with or without granules, are the commonly used protective surfacing."

Possible changes

A code change proposal was submitted to the International Code Council (ICC) to establish an exception so all layers of roofing material do not need to be removed when SPF-based roof systems are recoated. This first step of the process was successful—ICC's Fire Safety Committee approved a modified version of the proposal in September 2003.

ICC will take final action on this proposal at its 2004 final action consideration hearing May 17-20 in Overland Park, Kan. Code change proposals approved at that hearing will be published in IBC's 2006 edition.

James R. Kirby is an NRCA senior director of technical services.