Frequently Asked Questions

Polyiso is a closed-cell, rigid foam board insulation consisting of a foam core sandwiched between two facers. The foam core is formulated using an isocyanate and polyol mixture. The facers are composed of various organic and inorganic materials, including glass fiber reinforced felt, coated fiberglass mat, and aluminum foil (which may also be laminated and/or reinforced). Polyiso is widely used in residential and commercial construction markets for both roof and wall applications. For information on how polyiso is made, click here.

Polyiso insulation has attributes across many key performance categories for building insulation, including energy efficiency, fire, and ease of use. For a list and description of polyiso attributes, visit our website here.

Yes, polyiso insulation has a high R-value per inch when compared to other insulation products available to the market. This performance characteristic allows polyiso insulation to deliver greater energy savings potential in thinner product thicknesses. Additional information about polyiso R-value is available on the website here.

Long Term Thermal Resistance (LTTR) is a scientifically supported method to calculate the 15-year, time-weighted average R-value of closed-cell insulation products. Consensus-based standards for LTTR testing are published by ASTM and CAN/ULC. All polyiso manufacturing members of PIMA publish LTTR values for permeable-faced polyiso roof insulation sold in the United States. In Canada, LTTR-values are published for both permeable-faced and impermeable-faced polyiso insulation products. For additional detail about LTTR, click here.

The PIMA QualityMark Program is a voluntary program that allows polyiso manufacturers to obtain independent, third-party certified Long-Term Thermal Resistance (LTTR) values for polyiso roof insulation products. Additional information on the QualityMark Program is available here.

Polyiso products are an ideal choice for green and sustainable building designs. The environmental benefits of installing polyiso products include:

• High thermal efficiency, which can result in energy savings potential that is equal to 47 times the product’s embodied energy.

• Blowing agents with zero ozone depletion potential and low global warming potential.

• Recyclable through reuse where permitted.

• Recycled content (varies by product).

A complete list of polyiso benefits can be located here. For more information on the environmental benefits and impacts of polyiso insulation, please consult the industry-wide Environmental Product Declarations available here.

Leadership in Energy and 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. The LEED Rating System establishes minimum requirements for the various aspects of sustainable design, including:

• Sustainable Sites

• Water Efficiency

• Energy and Atmosphere

• Materials and Resources

• Indoor Environmental Quality

• Innovation and Design Process

Additional information on the LEED Rating System is available here.

Yes, the use of polyiso insulation products can result in the achievement of certain credits under the LEED Rating System. Possible credits include those related to overall building performance and material-specific criteria. For more information, please consult Technical Bulletin 116, An Integral Part of Sustainable Building and LEED Credits.

A Class A rating for a roof is only for external fire performance as tested to UL 790 or ASTM E108 test standard. A Class 1 rating indicates that the full roof assembly has been subjected to a series of tests as described in FM 4470 Approval Standard for Class 1 Roof Covers. The classifications are not interchangeable. For more information on Class A versus Class 1, consult Technical Bulletin 111, Class 1 and Class A Roof Assemblies are Not the Same. Importantly, polyiso insulation is only foam plastic insulation product for direct application to steel roof decks to earn FM Approval for Class 1 Roof Systems.

Yes, polyiso insulation is an effective solution for insulating residential buildings. Polyiso continuous insulation can improve the energy performance of a home while reducing air infiltration and moisture intrusion when properly installed as an air or weather barrier. Polyiso is used to insulate exterior walls, roofs and below-grade surfaces of homes. For additional information on the benefits of polyiso insulation for residential walls, click here.

Polyiso is the most-widely used insulation product for low-slope commercial roofing construction in the United States and Canada, and serves as one of the most critical components of a well-functioning roof. In addition to providing thermal protection for the roof system and building, polyiso insulation products can protect against moisture accumulation in the roof and can be used to add slope to the roof through the installation of tapered products. For more information on polyiso roof insulation, please consult our application webpage available here.

Yes, polyiso is used to insulate below-grade walls and below-slab. Polyiso insulation is often installed on the interior side of basements or on the exterior of below-grade walls. Installers should always consult the manufacturer’s installation instructions to verify that the product is approved for below-grade applications.

Yes, foil-faced polyiso is an effective insulation option for use in masonry and rain screen cavity walls. Typical construction practices provide for a cavity between the exterior continuous insulation and exterior wall covering to allow drainage of moisture and air flow. Polyiso insulation’s high R-value allows builders to achieve energy efficiency targets with minimal material thickness. For more information, please visit our residential and commercial wall application webpages.

Yes, polyiso is often used in metal roofing systems. Metal roofing manufacturers incorporate accessories for installation of the metal roof directly over the polyiso insulation. In addition, composite products that combine polyiso insulation and other substrates such as OSB may also be used. The metal roof manufacturer should be consulted for fastening requirements and other installation requirements.

Yes, polyiso can be used for projects located in termite or insect prone areas when installed in accordance with local building code requirements for termite protection and inspection. Polyiso insulation is not known to provide a food source for insects. Always consult the manufacturer’s installation instructions for application-specific information.

Industry guidance recommends, and the model building energy code in the United States requires, that continuous insulation installed above the roof deck be installed in multiple layers with staggered joints for a number of reasons, including:

• Reduced thermal bridging by limiting thermal loss at insulation joints.

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

• Reduced air flow across the insulation system.

Consult Technical Bulletin 113, Storage and Handling Recommendation for Polyiso Roof Insulation, for additional information.

Roofs:

Yes, polyiso roof insulation, like other roofing materials, should be protected from environmental conditions when staged on a job site and during installation. This is essential to ensure that the installed roof system is not compromised by moisture or other elements. Please consult Technical Bulletin 109, Storage and Handling Recommendation for Polyiso Roof Insulation, for additional guidance.

Walls:

Polyiso wall insulation products are designed to be resistant to environmental impacts like water. In fact, many products are installed to function as Water-Resistant Barriers (WRBs) that provide the drainage plane behind the exterior wall covering throughout the life of the building. Like other building materials, polyiso wall insulation should be stored properly on the job site to protect against damage prior to installation. Please consult manufacturer-specific instructions for additional storage guidance, or for information on the use of polyiso wall insulation as a WRB.

No. Many solvents contained in typical construction adhesives have no impact on polyiso performance when applied in accordance with manufacturer’s installation instructions. Always consult the manufacturer’s recommendations to determine the compatibility of adhesives with various roof system components.

PIMA does not provide information regarding the distribution or sale of polyiso insulation products. You may contact a polyiso manufacturer directly with your inquiry. A list of PIMA member manufacturers is available here.