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Testing LTTR

Professional Roofing



LTTR; long term thermal resistance; r-value;

During the past several years, the use of long-term thermal resistance (LTTR) method for determining and reporting R-values for plastic foam insulation has been implemented and is gaining acceptance in U.S. and Canadian roofing markets. Following is a summary of a research program in which NRCA participated. A work group tested R-values of aged insulation samples and compared results with the products' represented LTTR values.

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