Polyisocyanurate Roof Insulation R Value

The results also are somewhat lower than the results at 25 f 40 f 75 f and 110 f mean test tem peratures from nrca s 2009 testing.

Polyisocyanurate roof insulation r value. Polyiso insulation thickness r value chart. During late 2014 nrca conducted additional limited r value testing of polyisocyanurate insulation and found r values lower than the current lttr values. Background most roofing professionals recognize poly isocyanurate roof insulation loses some of its r value over time. New polyisocyanurate r values is a 2 page 2016 industry issue update from the national roofing contractors association nrca.

At the time polyiso cyanurate insulation is manufactured it has a relatively high r value. Fm approved subject to the conditions of approval as a roof insulation when installed as shown in the current edition of the factory mutual research approvals guide. Polyiso is unique in that the r value increases with the thickness of the foam so three inches of polyiso has a higher r value per inch than two inches. As the insu lation ages and is exposed to varying tem peratures and field conditions the.

Excellent lttr value compared to any other fm class 1 rated products of equivalent thickness. Tion for polyisocyanurate roof insulation. Polyiso has a high r value per inch compared to other insulation products. This industry issue update explains why the nrca recommends using a significantly lower r value for polyiso than pima does.

A higher r value means that the insulation will do a better job of holding in conditioned air whether that s heat in the winter or cool air in the summer.