Polyisocyanurate Roof Insulation R Value Per Inch

Membrane roof systems 2011 and the nrca roofing manual.

Polyisocyanurate roof insulation r value per inch.

The increase in thermal resistance for thicker products is due to the reduced contribution of more thermally conductive elements such as the facer and the denser cell. This industry issue update explains why the nrca recommends using a significantly lower r value for polyiso than pima does. R value chart for enerfoil tm rigid foam faced insulation conditioned per atsm c1289 test method astm c518 1 2. Benefits of energyguard polyiso roof insulation include.

Dated its r value recommendations for polyisocyanurate insulation used in roof systems. Firestone iso 95 gl insulation the highest thermal ratings. The reflective foil facing makes it an excellent insulation board when radiant heat is involved. 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.

Polyiso still remains the highest r value per inch of any available insulation. Jm suggests that design professionals use 5 7 r inch as a design specification for its foam products. Jm revised lttr values. 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.

Let s use the r value of iko s polyiso insulation enerfoil tm as an example. In the nrca roofing manual. For example a two inch polyiso product has more than twice the insulating value than a one inch product. Jm is proud to be a pima member and have its product third party certified under the pima quality mark program.

Additional r value for a masonry wall constructed using these materials needs to add the insulating value of additional wall components typically included such as 1 solid foam polyisocyanurate r 8 extruded polystyrene r 5 expanded polystyrene r 4 or 1 of perlite r 2 7 and for an exterior air film winter no wind r 0 17 an interior. New polyisocyanurate r values is a 2 page 2016 industry issue update from the national roofing contractors association nrca. Polyiso has a high r value per inch compared to other insulation products. Excellent lttr value compared to any other fm class 1 rated products of equivalent thickness.

Membrane roof systems 2015 nrca had recommended designers use in service r values of 5 0 per inch thickness in predominant. Keep in mind that polyiso s r value increases with thickness.