Delivering High R-Value Polyiso Insulation

Building professionals expect products to deliver the performance required to meet increasingly stringent standards for the construction of high-performance buildings and homes. No matter the performance metrics (e.g., structural considerations, energy efficiency, system performance, etc.) that drive the decision for material selection, products that use third-party certification programs to measure properties can provide an increased level of confidence to a building professional that they are making the right decision for their next project.

The Polyisocyanurate Insulation Manufacturers Association (PIMA) operates a voluntary program — the QualityMark Certification Program — for Canadian and U.S. manufacturers of polyisocyanurate (polyiso) roof insulation (ASTM C1289, Type II, Class I, Grade 2). The program enables participants to obtain third-party certification of long-term thermal resistance values (LTTR-values) for insulation products independently selected from manufacturing locations. Additionally, the program provides third-party verification of thermal resistance values (R-values) for full thickness products independently selected from distribution locations. PIMA partners with Intertek as the program’s independent administrator. Polyiso is the only insulation product to publish certified LTTR-values under an industrywide, third-party program.

Program History

Photo: GAF

The QualityMark program was first launched in the 2000s to enable polyiso manufacturers to obtain third-party certified LTTR-values for permeable faced polyiso roof insulation products. The program’s launch coincided with the industry’s adoption of LTTR-values following a rigorous test standard development process. In 2021, the program expanded to include third-party verification of R-values for full thickness products independently selected from distribution locations. The expanded program allows PIMA to provide end users with valuable information on performance by selecting and testing products on a more frequent basis. Results from the expanded program criteria will be published starting in 2023.

LTTR Testing for Polyiso Products

LTTR is a method that was adopted by polyiso manufacturers to develop predicted long-term thermal resistance for polyiso roof insulation. It is a scientifically supported, consensus-based method that was validated by a U.S. national lab. The method estimates the product’s thermal resistance by employing a technique called “slicing and scaling” to accelerate the aging process and provide a prediction of a product’s thermal resistance after five years. This five-year value is used because it corresponds to the product’s average thermal resistance over a 15-year period. Importantly, the LTTR methodology is suitable for evaluating insulation products that are manufactured with captive blowing agents.

There are numerous advantages of the LTTR method for designers, specifiers and contractors, including:

• It provides representative measure of long-term thermal resistance for polyiso insulation and other foam insulation products.

• It applies to all foam insulation with captive blowing agents other than air, such as polyiso, extruded polystyrene (XPS) and closed-cell spray polyurethane foam (SPF).

• It is an advanced test method, based on consensus standards in the United States and Canada.

• It is the subject of a rigorous study by Oak Ridge National Laboratory.

A heat flow meter is used to measure the thermal resistance and conductivity of insulation products. Photo: R&D Services

For the QualityMark program, participating manufacturers are required to certify the LTTR-values for roofing products every three years. Due to the nature of the test method and specimen requirements, product samples are randomly selected from each plant location’s warehouse by an independent third party shortly after production. The selected product samples are sent to one of five labs located in Canada or the United States, which are approved under the QualityMark program. The independent lab performs testing and analysis in accordance with the methods recognized by the governing polyiso product standards. The test results are submitted to the independent program administrator, who verifies the results conform to the program requirements.

R-Value Testing for Polyiso Products

In the United States, manufacturers of insulation products that utilize captive blowing agents may also report product R-values. For polyiso products, R-values are commonly reported for wall insulation products. R-value is measured on full thickness samples following a 180-day conditioning period. After conditioning, the thermal resistance is quantified under steady-state conditions (typically at 75˚F mean temperature) in accordance with the governing standards (most commonly the ASTM C518 test methodology).

For the QualityMark program, R-value testing provides polyiso manufacturers with the ability to test product samples on a more frequent basis. Therefore, in an effort to increase the number of samples selected and tested under the program, PIMA expanded the QualityMark program in 2021 to include R-value testing. This component of the program is again completed with the assistance of third parties and importantly without any participation from the manufacturer. Each quarter, an independent third-party visits product distribution sites located throughout Canada and the Unites States. Product samples representing each participating plant location are selected from these independent distribution sites. The product samples are packaged and sent by an independent third-party directly to the test lab for testing. Once the samples arrive at the lab, the products are stored for a period of time equal to 180 days from the date of manufacture. The conditioned samples are then tested and the R-values are quantified. The R-value results are reported to an independent third-party program administrator who verifies that the results conform to the program requirements. This process is repeated each quarter for each participating plant.

Increased Confidence With Measured Performance

The QualityMark program is designed to give the building professional community the confidence that specifying polyiso roof insulation means selecting the right product for the job. The program accomplishes this goal by involving independent third-parties in the selection, testing and management of the program. The recent expansion of the program provides manufacturers with additional data points on product R-values by more frequently testing products obtained directly from distribution locations that are familiar to the building professionals that specify and install polyiso roof insulation products each day.

Additional information on the QualityMark program is available at The website includes details on program participants and a list of approved, accredited labs for LTTR testing. Building professionals interested in learning more about the program should monitor the website for updates and news. Importantly, the information provided by the QualityMark program is offered for the user’s informational purposes only and is based on periodic testing of individual product samples. Users should always consult the individual product manufacturer’s materials, including but not limited to product installation instructions and datasheets, for information on product performance.

About the author: Marcin Pazera, Ph.D., is the Technical Director for Polyisocyanurate Insulation Manufacturers Association (PIMA). He coordinates all technical-related activities at PIMA and serves as the primary technical liaison to organizations involved in the development of building standards. Dr. Pazera holds a doctoral degree in mechanical engineering from Syracuse University and, over the course of his career, has worked in building science with a focus on evaluating energy and moisture performance of building materials and building enclosure systems. He has expertise in building enclosure and product manufacturing encompassed-research, testing, product conception and development, and computer modeling/analysis.

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