Frequently Asked Questions

Polyiso is a closed-cell, rigid foam board insulation consisting of a foam core sandwiched between two facers. The facers are composed of various organic and inorganic materials, usually paper and fiberglass. It is widely used in residential and commercial markets for both roof and side wall applications.

Polyiso insulation has many attributes. Polyiso provides:

  • A high R-value per inch of thickness when compared to other insulation products.

  • A moisture-resistant foam core.

  • Compatibility with most solvents used in construction adhesives.

  • Excellent dimensional stability 

  • Excellent performance in fire tests – Polyiso meets the strict standard of both FM Class 1 Approvals (FM 4450/4470), UL 1256, and CAN/ULC S126M.

  • A wide range of service temperatures

  • Long Term R-value (only roof insulation with third party certification)

  • A CFC- and HCFC-free product with zero ozone depletion potential 

  • Recycled content in most products (see manufacturer for details).

  • Negligible global warming potential. 

  • Availability throughout the U.S. and Canada.

Polyiso has a high R-value per inch when compared to other insulation products. This allows Polyiso products to deliver more energy savings potential for buildings than other materials of the same thickness.

Based on consensus standards in both the United States and Canada, Long Term Thermal Resistance (LTTR) is a scientifically supported method to calculate the 15-year, time-weighted average R-value of roof insulation. All Polyiso manufacturers of the Polyisocyanurate Insulation Manufacturers Association (PIMA) have adopted the LTTR method as the exclusive means to measure thermal performance of permeable-faced Polyiso roof insulation. PIMA Polyiso manufacturers have certified LTTR-value products verified by the QualityMarkcm Program. Click here to view more information on LTTR.

The PIMA QualityMark Certification program is a voluntary program that allows Polyiso manufacturers to obtain independent, third-party certification for the Long Term Thermal Resistance (LTTR) values of their Polyiso insulation products. Polyiso is the only insulation to be certified by this unique program for its LTTR value. The program is administered by FM Global and was developed by the Polyisocyanurate Insulation Manufacturers Association (PIMA) based on work done at Oak Ridge National Laboratory and CAN/ULC- S770.Click here to view more information on the QualityMark Program..

Polyiso insulation is an ideal choice for green building design, offering:

  • Reduced fossil fuel consumption. 

Well-insulated buildings reduce the need for energy, thereby reducing air pollution and greenhouse gas (GHG) emissions. BOMA currently represents roughly 9 billion square feet of roofing area. Reducing energy consumption by just 10 percent in these roofs is equal to planting 344,922,103 trees - a huge reduction in atmospheric CO2. The planting of these trees would also :

- Generate 10.7 trillion dollars of oxygen

- Control 10.8 trillion dollars worth of soil erosion

- Recycle 12.9 trillion dollars worth of water

- Provide 21.4 trillion dollars worth of air pollution control

- It would also be the equivalent of removing 42.7 million cars off the road for one year.

  • High Thermal Efficiency

Polyiso is one of the most thermally efficient insulation available in the marketplace, as determined using Long Term Thermal Resistance (LTTR) values, a 15 year time-weighted R-value. In addition, members of PIMA participate in a third party certification program – QualityMark – to validate these predicted thermal values. QualityMark is a voluntary program administered by FM Global, one of the nation's most dependable testing organizations

  • Zero Ozone Depletion Potential

All PIMA Polyiso manufacturer members produce rigid foam board with third-generation, zero ozone-depleting blowing agents. All Polyiso products are now HCFC-free and CFC-free.

  • Zero Global Warming Potential

All PIMA Polyiso manufacturing members produce rigid foam board with zero global warming potential blowing agents. This quality is critical as the impact of climate change is acknowledged as a worldwide environmental concern.

  • Recycled Content

Virtually all Polyiso insulation is manufactured using recycled material. The percentage of the recycled material by weight depends on the individual manufacturer and the thickness of the product. Many facers on Polyiso products contain up to 100 percent recycled materials.

*Information courtesy of Building Owners and Managers Association (BOMA) International 

Leadership in Energy & Environmental Design (LEED) Green Building Rating System® was developed by the US. Green Building Council (USGBC) in the early 1990s to measure the environmental impact of constructing a building. USGBC brought all sectors of the building industry together to develop a voluntary, national benchmark for "high-performing, sustainable buildings." PIMA supports this approach, and was one of the first trade associations to join USGBC when that organization opened its doors to industry groups.

The LEED Rating System establishes basic requirements for the various aspects of sustainable design:

Sustainable Sites

Water Efficiency

Energy and Atmosphere

Materials and Resources

Indoor Environmental Quality

Innovation and Design Process

Credits or points are earned for meeting the requirements of the specific LEED rating category. A threshold of 40 percent of the available points is required to achieve the minimum LEED Certified rating. Higher performance levels are designated as Silver, Gold or Platinum and are achieved by meeting minimum points for each level.

For more information, click the link below for PIMA Technical Bulletin 116 "An Integral Part of Sustainable Building and LEED Credits."

For more information on LEED, please visit http://www.usgbc.org and http://www.cagbc.org.

Using Polyiso insulation may help achieve credits under the LEED rating system. Here are some suggested opportunities to incorporate Polyiso in a building design using LEED for new construction and major renovations (Version 3):

Energy & Atmosphere

  • Minimum Energy Performance: Prerequisite 2
    Thermally efficient Polyiso facilitates compliance with ASHRAE 90.1-2007 and local energy codes.

  • Optimize Energy Performance: Credit 1
    Polyiso provides the highest thermal resistance per inch of material and can economically contribute to achieving one of the LEED levels of optimized energy performance.

Materials & Resources

  • Construction Waste Management: Credit 2 If the total percentage of reused materials in a project does not meet the minimum levels stated in Materials and Resources, Credit 1, Building Reuse, these reuse activities may be applied to this credit.

  • Materials Reuse: Credit 3 Polyiso can be and often is reused in order to reduce demand for virgin materials and reduce waste. Recycled Content: Credit 4Depending on the product, Polyiso can be used toward one of the levels of recycled materials credit.

  • Recycled Content: Credit 4 Depending on the product, Polyiso can be used toward one of the levels of recycled materials credit.

  • Local/Regional Materials: Credit 5 PIMA's six manufacturing members have Polyiso insulation plants and source materials across North America. Therefore, the use of Polyiso may contribute towards gaining this credit, depending on the version of LEED being used as the basis of design.

  • Rapidly Renewable Materials: Credit 6 Depending on the product composition, and thickness, Polyiso can be used toward one of the levels of rapidly renewable materials credit.

  • Certified Wood: Credit 7 FSC-certified wood when used in products where Polyiso is bonded to the wood can contribute to gaining this credit.


Polyiso insulation offers the most extensive range of code approvals for insulation use in roof systems. It remains the only foam plastic insulation product for direct application to steel deck to earn FM Approval for Class 1 Roof Systems.

A Class 1 roof is often confused with a Class A roof. Class 1 roofs consider several attributes of the roofing assembly, such as under deck fire spread, resistance to external fire exposure, wind uplift resistance and hail resistance. Conversely, Class A roofs consider only resistance to external fire exposure of the roof assembly. Not all Class A roofs meet Class 1, so they should not be treated as equals. The distinction between these types of roof classifications becomes even more critical when the roof system contains foam plastic insulation, such as Polyiso, polystyrene or polyurethane.

The designation of "Class 1" can be granted only by FM and reflects the successful testing of the whole roof assembly using FM 4470 standard. According to the scope of FM 4470, "because the fire performance of a roof cover depends in part upon the substrate materials to which it is applied, it is therefore necessary to evaluate the roof assembly as a whole, including the cover and auxiliary items necessary to build-up a roof assembly." Class A, B or C is a measure of the external spread of flame on a roof surface. A number of fire test laboratories including Underwriters Laboratories (UL), Underwriters Laboratories Canada (ULC) and FM Global (FM), conduct this test using either the ASTM E 108, UL 790, or CAN/ ULC –S107-M Standard. The best rating achieved is Class A, which is described by UL/ULC as "effective against severe fire exposure." For more information, click the link below for PIMA Technical Bulletin 111 " Class A and Class 1 Roof Assemblies Are Not the Same."

Foil faced Polyiso insulation is suitable for use in masonry and rain screen cavity walls. Both commercial and residential buildings typically require a "cavity wall" of air space and insulation between the brick veneer or rain screen and the interior to provide protection from weather and fire. Since the required thickness of insulation affects the cost of construction, an increasing number of builders and architects are choosing Polyiso cavity wall insulation due to its superior R-value to thickness ratio.  

When properly specified and installed, Polyiso sheathing insulation can be one of the best values available for residential construction. Its benefits include:

  • A residential wall system with a high R-value, which increases the energy efficiency of the home and significantly reduces heat loss

  • A reduction in air infiltration and exfiltration, which increases the overall performance of the wall and reduces heat loss.

  • A reduction in the risk of water condensation/intrusion, which increases thermal and structural performance and reduces builder call backs.

  • Insulation over the entire framing members, which reduces the loss of energy from the home and contributes to a more uniform comfort level.

  • Increased home builder confidence with an assurance that the builder is providing a quality product.

  • Increased home buyer/owner confidence with assurance of a quality home with state-of-the-art energy-efficient construction techniques.

  • Availability throughout the U.S. and Canada.

Insulation is one of the most critical components of a roof, providing much needed thermal performance in today's energy conscious world. Polyiso's unique benefits, strength and versatility allow it to adapt to a variety of roofing applications. Its benefits include:

  • High R-value per inch

  • Outstanding installed cost advantages

  • Only roof insulation with third-party certification of thermal performance

  • Meets both FM 4470, UL 1256, and CAN/ULC – S126M.

  • Available throughout the U.S. and Canada

Polyiso is often used in metal roofing systems. Metal roofing manufacturers incorporate metal clips with distribution plates for application of the metal roof directly over the Polyiso.

In addition, composite products that include Polyiso insulation and an OSB surface are also used. The metal roof manufacturers should be consulted for fastening requirements and other installation requirements.

The moisture content in a Polyiso board with glass fiber reinforced felt as manufactured is approximately 5 percent. Please note that the moisture content at the job or manufacturing site will vary according to ambient conditions and the type of facer used. 

Multi-layering of Polyiso roof insulation installed with staggered joints offers a number of advantages, including:

  • Reduced thermal loss at insulation joints

  • Reduced thermal bridging

  • Reduced moisture migration from the building interior into the roofing system

  • Reduced potential for membrane splitting in Built Up Roofing (BUR) systems

For more information, click the link below for the PIMA Technical Bulletin 113 "Multi-Layering of Polyiso Roof Insulation ."


Yes, it is still necessary to cover the insulation. The glass fiber reinforced felt used as the facer for most polyiso roof insulation should never be allowed to get wet whether from overnight rainfall or dew. The felt facer can and will absorb water, and it is never a good idea to trap it within the roof system. For more information, click the link below for PIMA Technical Bulletin 109 " Storage and Handling Recommendations for Polyiso Roof Insulation."


Most Polyiso wall insulation products are extremely water resistant. In fact, many are used as Water-Resistant Barriers (WRB) providing the drainage plain behind the veneer throughout the life of the building. WRBs are often left exposed to the elements while the rest of the wall assembly is constructed. For specific instructions and recommendations on how to properly complete the WRB and/or prepare the Polyiso wall insulation during this time, refer to the specific manufacturer.

Many solvents contained in typical construction adhesives have no appreciable effect on Polyiso foam when applied in accordance with manufacturer recommendations. Softening and degradation of the foam can occur when the adhesives are not applied according to the manufacturer's recommendations.