{"id":8349,"date":"2018-09-21T09:11:39","date_gmt":"2018-09-21T14:11:39","guid":{"rendered":"https:\/\/www.iko.com\/comm\/?p=8349"},"modified":"2025-08-25T14:11:48","modified_gmt":"2025-08-25T19:11:48","slug":"what-is-polyiso-rigid-foam-insulation","status":"publish","type":"post","link":"https:\/\/www.iko.com\/comm\/blog\/what-is-polyiso-rigid-foam-insulation\/","title":{"rendered":"What is Polyiso Rigid Foam Insulation? A Comprehensive Guide"},"content":{"rendered":"

What (exactly) is Polyiso?<\/h2>\n

Polyiso, or polyisocyanurate, is a rigid foam insulation used in more than 70% of commercial roof construction and offers a continuous insulation solution for\u00a0commercial flat (low slope) roof insulation<\/a>\u00a0and wall assemblies. As one of North America\u2019s most widely used and readily available building products, polyiso is a cost-effective insulation option for reducing building energy use and improving the overall service-life of roofs and walls.<\/p>\n

Specifically, polyiso has four major components: MDI, polyol, a blowing agent and a flame retardant. When these components are mixed, along with small amounts of catalysts and surfactants, a heat-generating chemical reaction causes the liquid blowing agent to boil. The resultant blowing agent vapor expands the foam, creating gas-filled cells that provide polyiso\u2019s high thermal-resistance value. The polyiso industry uses the hydrocarbon blowing agent pentane, which has zero ozone-depletion potential and negligible global-warming potential.<\/p>\n

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\nPolyiso Foam Cell Structure<\/p>\n

History\/Why It\u2019s Important<\/h2>\n

Polyisocyanurate was introduced in the building market during the late 1970s. At that time, chlorofluorocarbons (CFCs) were used in the manufacture of polyiso, with CFC-11 as the specific blowing agent. Although the history of the connection between CFCs and ozone layer depletion is well-documented, a brief\u00a0timeline of the issue<\/a>\u00a0and its implications for the industry provides more details.<\/p>\n

Throughout the 1970s and 1980s, the international community became increasingly concerned that Ozone Damaging Substances (ODS) would harm the ozone layer. The stratospheric ozone layer filters out harmful ultraviolet (UV) radiation. Exposure to UV rays are associated with an increased prevalence of skin cancer, cataracts, reduced agricultural productivity, and disruption of marine ecosystems. In 1985, the\u00a0Vienna Convention for the Protection of the Ozone Layer<\/a>\u00a0formalized international cooperation on this issue. This cooperation resulted in the 1987 signing of the\u00a0Montreal Protocol on Substances that Deplete the Ozone Layer<\/a>.<\/p>\n

Following the Montreal Protocol, new data showed worse-than-expected damage to the ozone layer. In 1992, the parties to the Protocol decided to alter the terms of the 1987 agreement to end production of CFCs by 1996 in developed countries.\u00a0More information on the phaseout of ODS is available here<\/a>.<\/strong>\u00a0Because of measures taken under the Montreal Protocol, emissions of ODS are falling, and the ozone layer is expected to recover by the mid 21st century.<\/p>\n

Specific to the roofing industry and polyiso as a product, the Polyisocyanurate Insulation Manufacturers Association (PIMA) was born out of a joint effort to find alternatives to the CFCs, with six founding members, including manufacturers and suppliers. For the first 15 years in the organization\u2019s history, PIMA focused on finding and improving alternatives to CFCs and HCFCs. In 2002, the industry transitioned to non-ozone depleting substances that were also ozone friendly.<\/p>\n

PIMA President Justin Koscher says the organization was formed at a time when CFC\u2019s were being phased out and taxed. \u201cAlthough CFC\u2019s were used as the blowing agent used in manufacturing process of polyiso during the 1980s, they were later proven to destroy the ozone in the earth\u2019s stratosphere,\u201d he notes.<\/p>\n

Benefits and Uses of Polyiso<\/h2>\n

Polyiso is a popular choice for\u00a0commercial roofing insulation<\/a>, as a roofing cover board, and in building envelope applications as an insulated wall sheathing. An alternative to other rigid foam plastic and fibrous insulation products, the many benefits of using polyiso products include:<\/p>\n