May 2010
Search    

R-value concerns | Tech Today

Tech Today 5 stars5 stars5 stars5 stars5 stars

R-value concerns

R-values are found to be below LTTR

by Mark S. Graham
Be the first to comment


NRCA has conducted limited R-value testing of high R-value rigid board insulation. The tests' results show R-values lower than the products' published long-term thermal resistance (LTTR) values. If you design roof systems using high R-value rigid board insulation, you should be aware of this data.

NRCA testing

NRCA obtained 15 samples of new (uninstalled) 2-inch-thick, felt-faced polyisocyanurate insulation from NRCA contractor members throughout the U.S.

The samples were provided to R & D Services Inc., Cookeville, Tenn., for R-value testing conducted according to ASTM C518, "Standard Test Method for Steady-State Thermal Transmission Properties by Means of the Heat Flow Meter Apparatus." The samples' R-values were tested as received, meaning without any additional aging. The samples ranged in age...



To read the article in its entirety, please log in or register (registration is free).

Log in or register for FREE access to this article and other Professional Roofing online content.

Not a professionalroofing.net user?

Register now for free access
  • Full access to every article
  • Online Web exclusive information
  • Photo gallery
  • Breaking news
  • Online classified ads

Already a professionalroofing.net user?

Log in now

User name:

Password:

 


Login help
Click here to have your user name and password emailed to you.




Comments (0) Login to post a comment or rating
There are no comments posted.

NRCA NRCA