National Roofing Contractors Association revises R-value of polyisocyanurate (ISO) insulation

NRCA has updated their R-value recommendation for polyisocyanurate roof insulation with the publication of the 2011 The NRCA Roofing Manual: Membrane Roof Systems.

The new recommendation for R-value is based upon testing by NRCA from 2005 to 2009 on current generation polyisocyanurate roof insulations. The new NRCA R-value recommendations are as follows:

R-value = 5.0 per inch thickness in heating conditions.

R-value = 5.6 per inch thickness in cooling conditions.

Review the Technical Bulletin [1]