Johns Manville Cool Roof Granulated Membranes: Improved Reflectivity and SRI Performance!
Oct. 20, 2026
Granulated cool roof asphalt membranes provide a durable, low-maintenance solution for building owners seeking a highly reflective, multi-ply roofing system. Unlike factory- or field-coated membranes, granulated cap sheets provide a reflective surface that does not require recoating throughout the roof’s life cycle, reducing maintenance for the building owner. Cap sheets with reflective granules also simplify installation for the contractor by not requiring removal of the factory-applied coating at end laps, or additional field coating of bleed out at side laps.
Johns Manville CR G membranes are available with multiple reinforcement options and can be used in SBS, APP, or BUR asphaltic systems. The JM CR G portfolio also provides installation flexibility, with options for hot asphalt, cold adhesive, or torch application.
As product and process technologies continue to improve, JM has pursued updated Cool Roof Rating Council (CRRC) ratings to better reflect product performance.
| Property | Old Ratings - SBS/APP/BUR | New Rating - SBS | New Rating - APP | New Rating - BUR |
|---|---|---|---|---|
| Solar Reflectance | Initial - 0.70 3-Year* - 0.65 |
Initial - 0.71 3-Year* - 0.68 |
Initial - 0.73 3-Year* - 0.70 |
Initial - 0.71 3-Year* - 0.69 |
| Thermal Emittance | Initial - 0.90 3-Year* - 0.91 |
Initial - 0.90 3-Year* - 0.90 |
Initial - 0.90 3-Year* - 0.90 |
Initial - 0.91 3-Year* - 0.91 |
| SRI | Initial - 85 3-Year* - 80 |
Initial - 87 3-Year* - 83 |
Initial - 90 3-Year* - 86 |
Initial - 87 3-Year* - 84 |
| CRRC Prod. ID | 0662-0042c | 0662-0042d | 0662-0056 | 0662-0057 |
*CRRC Rapid Ratings: Interim laboratory-aged values that simulate naturally-aged values and will be replaced by the measured three-year naturally-aged values upon completion of the weathering process.
The updated ratings demonstrate improvements in solar reflectance and Solar Reflectance Index (SRI) for both initial and 3-year Rapid Ratings. These improved ratings allow JM asphalt systems to meet some of the most stringent building code reflectivity requirements, including California’s Building Energy Efficiency Standards (Title 24, Part 6) and Los Angeles County Title 31 Green Building Standards.
Learn more about JM asphaltic products and the CRRC at the links below.