Certified Polymer Thickness
As a building owner, if a manufacturer sells you a 45 mil membrane, you assume there is that much “polymer” throughout. Not so. The polymer used in a roofing or waterproofing membrane is critical to the longevity, durability and weldability of the membrane. An increase in polymer can improve the long-term performance of the roof.
According to ASTM guidelines, “nominal” polymer thickness can be up to 10% off in its advertised amount – and there’s no way for you to know. Lower than advertised polymer thickness can reduce a membrane’s puncture resistance and the overall performance of your roof or waterproofing system.
| Manufacturer | A Advertised Thickness (MILS) | B Actual Measured Thickness (MILS) | C Difference A-B (MILS) |
| TPO F | 45 | 45 | 0 |
| TPO J | 45 | 31 | -14 |
| TPO C | 45 | 43 | -2 |
| PVC K2 | 45 | 43 | -2 |
| PVC K | 36 | 33 | -2 |
| PVC N | 50 | 46 | -4 |
| PVC M | 50 | 44 | -6 |
| PVC V | 50 | 40 | -10 |
| PVC M2 | 40 | 34 | -6 |
| PVC F | 48 | 43 | -5 |
| PVC D | 35 | 28 | -7 |
| Sarnafil S membrane | 48 | 49 | +1 |
| Sarnafil G membrane | 48 | 48 | 0 |
Source: Comparative Testing and Rating of Thirteen Thermoplastic Single Ply Membranes - 1998 study conducted by C.G. Cash of Simpson, Gumpertz and Heger
Certified Polymer Thickness
Discrepancies in nominal polymer thickness is why Sika Sarnafil introduced a Certified Polymer Thickness program. Our goal is to give the building owner, architect and specifier a guarantee that what they buy is what they get. It also helps heighten the awareness and importance of fair product comparisons. When multiple manufacturers are named in a specification, a certified polymer thickness requirement establishes a more uniform basis for comparison. This way, all specified products are required to meet the same polymer thickness criteria.
Sarnafil - Proven Performance - Thickness Certificate
For your next project, specify a minimum polymer thickness – not a minimum sheet thickness. Also, consider requiring the manufacturers to submit a certificate of analysis. It’s really the only way you’ll be sure the product delivered meets your performance criteria.