The RCI Foundation has approved a two-year research grant totaling up to $50,000 to SPRI (representing the Single-Ply Roofing Industry) for research on the roofing assembly. SPRI is a collection of commercial roofing industry experts dedicated to providing an open forum for discussion, education, and innovation.

The objective of this study is to measure and record the influence on roof substrate materials as moisture content varies. In this research, the equilibrium moisture content will be recorded at two temperature and relative humidity conditions (winter and summer in ASHRAE Zone 3 has been selected). At equilibrium and Thermal Resistance Ratio 80 (TRR-80), determined by testing on current materials, the influence of moisture concerning compressive strength, stability of dimension and density, flexural strength, and fastener pull-through will be recorded. TRR-80 is the amount of moisture that could be present with each material before it loses 20% of its thermal resistance.

The resulting data will be published for free use by the roofing industry and others to judge the ability of existing in-service roof substrate materials to be reused or repurposed. This information is of great value when determining if substrate materials can be left in place when considering a roof recovery project. It is also useful when the roof is tested directly after installation as a specified condition of acceptance.

There are some data available that can be used for this evaluation; however, most of this information is over 30 years old and does not include modern-type products that are used as substrates. A list of current-day roof substrate products (using generic designations) to be included in the testing process, along with a list of ASTM test procedures available for use to obtain the data have been developed for this study through SPRI task force efforts.

The goal of this research is to provide current data that will allow roof consultants and other roofing industry stakeholders to make more informed decisions regarding the suitability of the substrate when testing for roof recovery options and new installation projects. Expected completion date is November 2019.

“SPRI is excited to have the support of the RCI Foundation for this very important research project. The data generated from this project will be extremely helpful in making informed decisions about the suitability of leaving an existing substrate in place installing a new roof system,” says SPRI Technical Director Mike Ennis.

If you have questions or would like more information about the RCI Foundation, please contact Development Officer Rick Gardner at or call 919-859-0742.