The Physical Attributes of Polyiso Make it a Preferred Insulation Product

October 12th, 2011

Most roofing professionals understand the well-documented insulating value of polyiso (polyisocyanuarate). It’s the go-to product for thermal resistance and R-value performance for flat roof insulation and is also used in many commercial and some residential wall applications. What is equally impressive about polyiso is the myriad of physical characteristics and properties that make it easy and efficient for contractors to work with.

Polyiso is strong and rigid. Its dimensional stability makes it useful to provide strength and support to a structure in addition to the insulating value it delivers. For example, when used as an additional layer in BUR applications it creates a solid thickness of reinforcement to the roof structure while insulating. Other types of insulation would occupy the same space and provide temperature control without adding strength.

Polyiso can be applied in a wide range of temperatures. It’s not brittle in cold and doesn’t melt when exposed to excessive heat. When manufactured with a facer it can be mopped with hot asphalt. Even though it’s possible to burn polyiso, the material performs well in fire tests. Instead of melting or burning away, it stays in tact and actually forms a protective char layer.

Polyiso is moisture resistant, so it is a preferred product to have underneath the roofing membrane. While it shouldn’t be constantly drenched, it doesn’t wick water. It actually repels water and contains a foam core that’s moisture resistant. This makes it not only easy to work with during storage and installation, but gives it longevity as part of the building envelope.

Polyiso isn’t only practical in it’s use, but efficient to manufacture. Atlas ACFoam® products are manufactured using recycled materials. An ACFoam® panel contains between 16% and 43% recycled materials by weight. All foam panels contain a percentage of recycled materials relative to their thickness. Since the facers for polyiso panels are made of 100% recycled materials, a thinner panel will have a higher percentage of recycled materials.

Finally, polyiso materials, unlike other insulations materials such as polystyrene, is friendly to most solvents. Most construction adhesives, paints, stains or or other preservatives won’t cause polyiso to dissolve, so contractors can use it without concern that damages will result from use of solvent based products.

The new interactive Green Zone LTTR Calculator is one of the best ways to determine polyiso dimensions and specifications for any roofing insulation project. Using the new system located at, users enter their desired R-values, AHRAE standards and roof dimensions to configure the most efficient polyiso solution.