Updated LTTR Information

On January 1, 2014, Firestone Building Products began reporting Long Term Thermal Resistance (LTTR) of our ISO 95+™ and RESISTA™ flat and tapered commercial roof insulation products in accordance with the ASTM C1289-13e1 testing standard.

LTTR1Since the process of CO2 and Pentane diffusion occurs at a slower rate in thicker polyiso products, we reported LTTR values using a progressive scale beginning with 5.6 per inch.  Subsequent testing has revealed no appreciable difference between diffusion rates in products less than 2.0” thick and products between 2.0” and 2.9” thick.  Because of these results, we are certifying that all products less than 3.0” thick will perform at the LTTR value of 5.7 per inch.

The shift from 5.6 per inch to 5.7 per inch affects the product appearing in the below table:














At Firestone Building Products, it’s more than just getting the products you need for your projects.  It’s getting a complete solution – exceptionally performing building materials backed by a brand and people you can trust.  For more details regarding these changes, please visit the 2014 UPDATED LTTR Information or contact your local Firestone Sales Representative.

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