Insulation in the extreme

by brittney_cutler | September 1, 2021 12:00 am

Photos courtesy Owens Corning

by Tiffany Coppock, AIA, NCARB, CDT, LEED AP

Could events of the past year be considered anything other than extreme? Beyond the global pandemic and events in the news, both episodic weather events and new environmental regulations are placing extreme demand on building materials, including insulation. This article considers insulations’ role in commercial roofs and other areas of the enclosure subject to extreme demands. Insulation will be viewed through the lens of extreme weather, more stringent regulatory requirements, and performance concerns posed by mission-critical buildings.

Extreme weather, climate concerns, and new regulations

Historic wildfires in the West, tropical storms in the South, derechos in the Midwest, and an infusion of artic air devastating parts of Texas are just some of the recent climate events underscoring the need for commercial roofs to be able to withstand extreme moisture, wind, and thermal conditions. Extreme weather conditions has left virtually no part of North America unscathed.

Weather like this can influence code changes. Managing stormwater runoff is a good example. As noted in the October 2020 issue of The Construction Specifier, vegetative roof assemblies (VRAs) are a popular means of adding space and access to nature while also providing strategic approaches for managing stormwater[2]. Mandatory ordinances in the United States supporting vegetative roofs have been in place in some cities since 2007[3]. As interest in sustainable roofs continues to grow, ordinances are beginning to show change and other ways to further reduce buildings’ impact on the environment must also be considered.

In response to climate change, the Canadian government and a growing number of U.S. states have enacted new environmental regulations to support slowing the climate change impacting extreme weather. Currently within the United States, environmental regulatory action is taking place at the state level. On January 1, 2021, new regulations became effective in California, Colorado, New Jersey, New York, Vermont, Washington, and all of Canada banning the use of high global warming potential (GWP) hydrofluorocarbon (HFC) blowing agents. More states are planning to enact similar laws. As of this writing, Massachusetts, Maryland, and Delaware have finalized laws and regulations to lower the GWP levels of blowing agent formulations. Those will go into effect later this year, and several more states have proposed legislation[4]. During the transition, accommodations were made to allow for a grace period of selling existing, non-compliant material and preventing the production or sale of additional material in affected states. It is recommended to review each state’s requirements for compliance.

A reduction in GWP supports sustainability

The target of these new regulations was not only rigid insulation board, but also mandating lower levels of GWP in blowing agents impacting products like extruded polystyrene (XPS.) Blowing agents are a key ingredient allowing XPS to deliver high thermal performance. Moving beyond regulatory compliance, the new environmental regulations are also inspiring environmentally conscious designers and contractors to think about how insulation can support sustainable buildings alongside manufacturers of these materials.

These new regulations—coupled with awareness surrounding life cycles—are mainstreaming once novel innovations such as recycled content, low GWP formulas, and longer-use products reducing the overall environmental footprint of buildings. Manufacturers with a continuous focus on this sustainability mindset are helping lead this effort in putting materials that are constantly being improved into the hands of designers.

A corroded reinforcement embedded under the pool structure is visible in this image.

An extreme undertaking of product innovation

While the environmental regulations are new, approaches to a lower-GWP insulation have been years in the making at some companies. Leading companies have been working toward this goal through multiple previous formulas. The challenge in creating a lower-GWP XPS was daunting because the reduction in GWP could not detract from the superior properties that support XPS’s performance attributes which has been achieved with varying levels of success by different manufacturers.

The next generation in XPS can be installed in applications across the building enclosure from foundations to vegetative roofs; in some cases, sustainability features are validated by a third-party verified Environmental Product Declaration (EPD) and Optimization report. The EPD can provide designers and specifiers with documentation for specifying and installing this material to meet rating systems such as the U.S. Green Building Council (USGBC) Leadership in Energy and Environmental Design (LEED), Environmental Protection Agency (EPA) Energy Star, and the National Association of Home Builders (NAHB) National Green Building Standard.

Extreme missions: Insights from Europe

In Europe, a different type of insulation is addressing ‘extreme’ applications. ‘Extreme’ in this case refers to ‘mission critical’ buildings where the breach of a roof membrane and resulting water leak could threaten priceless contents or disrupt a critical process resulting in risk to the health, safety, or welfare of occupants or the community.

In these mission critical buildings, cellular glass insulation is the product of choice because of one or more of its performance characteristics—lightweight, water, and vapor resistance, non-combustibility and high compressive strength to name a few. Notable examples of some mission critical buildings include the new Acropolis Museum in Athens, Greece, the Stora-Enso facility in Ghent Belgium, and the Firstsite Centre in Colchester, United Kingdom.

Each of these buildings presented an extreme challenge for designers and contractors: how best to protect the artifacts or mission critical process inside. These high-profile installations are explored in more detail below.

Stora Enso’s Langerbrugge Mill in northwestern Belgium is home to the world’s largest newsprint machine. From a sustainability perspective, the facility is also a leader in renewable materials replacing fossil-based resources.

Protection for ancient artifacts: Insulation in action

Located in the historic Makryianni district, collections in the New Acropolis Museum take visitors on a tour of both late antiquity and ongoing conservation and research efforts. At the museum’s base, foundation columns and glass floor were carefully engineered to allow visitors to look down upon an active archeological excavation of ruins from the 4th and 7th centuries A.D. A double-height trapezoidal plate in the middle section of the ‘cube’ is home to galleries from the Archaic period of the Roman era. At the top level, natural light floods the top floor Parthenon gallery, bringing a panoramic view of modern Athens and the Acropolis and connecting the architecture strongly to its site.

Constructed in the shape of a cube and situated below the Acropolis, the museum’s flat roof using a cellular glass insulation complements the structure’s clean, geometric aesthetic while reducing weight on the unique foundation and managing rooftop drainage due to tapering the insulation. This cellular glass insulation in the main roofing system sits atop a metal roof deck that includes fully adhered insulation, two layers of reinforced waterproofing membrane, and an embedded protection course. This surface is connected with a insulation serrated plate, screw, and rubber air- and water-sealing gasket ring to support structure underneath opaque glass to complete the glass cube concept. As noted, this not only visually reduces the building’s weight but provides less structural weight to the building without compromising thermal protection of the roof and adding to the critical mission of protecting artifacts from potential water infiltration. Ease of handling was a bonus during construction, as the cellular glass could be tapered during manufacture and easily cut in the field to accommodate lightening protection and variations in construction tolerance.

An extreme enclosure and roof evoke a ‘sheathed in gold’ effect

‘Extreme’ is an apt metaphor for the FirstSite Centre. The golden-clad crescent is a work of art embracing its historic surroundings of heritage gardens and sites as well as housing historic artifacts within. Ensuring developers did not disrupt historic sites did not compromise the mission to provide educational opportunities while actively commissioning and exhibiting artists of the present and future to form Colchester’s ‘future heritage.’ Connecting the public to art, the center includes gallery spaces for hosting workshops, lectures, exhibits, and events. Yet another facility built atop a historic artifact, the Berryfield mosaic, dating back to 200 A.D. and discovered in 1923, is protected under a glass case built into the floor. As a result, the foundation was engineered as a concrete ‘raft’ due to a ‘no dig’ policy.

In this roof assembly, the cellular glass insulation was adhered to the structural deck with cold adhesive. Square plates were then embedded into the insulation and covered with the torch-applied roof membrane. Additional metal grips were screwed through this plate to create the attachment skeleton for the standing seam gold sheets (a copper and aluminum alloy). In a traditional architectural metal roof, these fasteners would have penetrated the roof membrane and the insulation to attach to the structure below. However, the method used here eliminates through-fasteners and therefore thermal bridging. The waterproof, dimensionally stable and high-compressive properties of the cellular glass also help hold the fasteners through the membrane securely and add a layer of waterproof material. This unique solution creates both a visually appealing extreme roof and protects valuable building contents.

In the Makryianni district of Greece, collections in the New Acropolis Museum take visitors on a tour of late antiquity and ongoing conservation and research. At the museum’s base, foundation columns and glass floor were carefully engineered to allow visitors to look down upon an active archeological excavation of ruins from the 4th and 7th centuries A.D.

Extreme processes define industrial operations

Beyond ancient artifacts and treasures, mission critical buildings housing industrial assets also protect extreme processes. A good example is Stora Enso’s Langerbrugge Mill in northwestern Belgium. The facility is home to the world’s largest newsprint machine. From a sustainability perspective, the facility is also a leader in renewable materials replacing fossil-based resources. In 2019, the company announced a pilot facility for enabling the production of bio-based plastics and found a way to recycle used paper cups to cut the carbon footprint of disposable paper cups by 50 percent.

Once again, cellular glass plays a role in topping off this treasure. A cellular glass roof tops the 22,000 m2 (236,806 sf) area of flat roofs at the Langerbrugge Mill. The material composition aligns with the company’s investment in ecologically responsible activities. Totally inorganic, the cellular glass insulation used on this project does not contain any ozone-depleting propellants, flame retardants, or binders, and is free of volatile organic compounds (VOCs). Cellular glass is aligned with these company goals as it is a product with up to 60 percent recycled content.

Industrial applications require massive strength on the roof as mechanical systems, heavy equipment, and even maintenance vehicles are often placed atop the structure. The Langerbrugge Mill’s rooftop supports mechanical and electrical equipment, requiring extreme loadbearing capacity. The compressive strength of cellular glass insulation begins at 345 kPa (50 psi) and is regularly used in building applications reaching 1655 kPa (240 psi). Dimensional stability and resistance to deflection is another consideration. The predominantly glass composition of cellular glass provides a low coefficient of thermal movement that is comparable to the movement of the concrete or steel decks to which it typically attaches. This quality means warping, dishing, or shrinking of the insulation does not occur. Cellular glass provides a stable foundation for the roofing membrane minimizing the stress placed on its joints and thereby prolonging the life of the roof.

Of particular concern in industrial applications, cellular glass is preferred where flammable liquids are used. Cellular glass is not a fuel source as it is non-combustible. It is classified as a Class A material per ASTM E84, Standard Test Method for Surface Burning Characteristics of Building Materials, due to zero flame spread and zero smoke development in independent third-party testing.[8]. This serves as an added benefit in critical facilities where threat of fire is increased and shutdown due to fire would result in significant loss.

One of the key reasons cellular glass was ideal for the Langerbrugge Mill was its vapor impermeable property. The printing process creates a significant vapor pressure that must be countered to protect the membrane and other roof components. Cellular glass has a maximum vapor permeability of 0.005 perms per inch Class I vapor retarder per ASHRAE 90.1 (per ASTM E96 Standard Test Methods for Water Vapor Transmission of Materials Method B) compared to a range of 0.1 to 10 for similar rigid board insulation products (Class II or Class III). Limiting vapor transmission is also especially important in applications where the vapor is a chemical. Cellular glass is also acid- and chemically resistant, making it ideal for this and other pipe insulation applications.

Historic wildfires in the West, tropical storms in the South, derechos in the Midwest, and an infusion of artic air devastating parts of Texas are just some of the recent climate events underscoring the need for commercial roofs to be able to withstand extreme moisture, wind, and thermal conditions.

Extreme functions critical to infrastructure

Back in the United States, these physical properties were put to good use in extreme climates and roof applications. The Jardin Water Treatment Plant in Chicago, Illinois, can treat 3,785,412 L (1 million gal) of water a minute to serve Chicago and the surrounding area[10]. The health of this community relies on this building to remain functioning, and downtime is simply not an option, even in humid summer highs or freezing winter lows. While the cellular glass serves as a redundant layer to prevent roof leaks, treatment of drinking water with chlorine and other chemicals to disinfect and remove contaminants also necessitates an insulation resistant to chemical exposure[11]. Cellular glass uniquely solves this extreme problem.

Over 50 years ago, cellular glass insulation was embedded as part of the roof membrane system. In 2009, as the roof membrane assembly was reaching the end of its expected lifespan, the insulation samples were removed from this roof and tested by an independent third party for its performance after so many years in service. Some of these results included no sign of freeze-thaw erosion, thermal performance as claimed, and negligible moisture content. After this proven performance, the same insulation was selected for installation on the Eugene Sawyer Facility, Chicago’s other mission-critical water treatment plant.


In Europe, United States, and around the globe, designers must consider many extremes when it comes to the roof. The compliance standards are also rising, and safety is non-negotiable while improving impact on the planet. Innovations to familiar materials such as XPS are supporting growing sustainability efforts. Meanwhile, designers are innovating roof assemblies using time-tested cellular glass to meet extreme roof performance requirements.

Materials may be considered for their ability to create better roof drainage or even retain more moisture on a roof to relieve increased pressure on storm sewers. They may require a material to provide high compressive strength to accommodate fasteners and traffic. Or they may need extreme resistance to moisture and chemicals to support an entire community with vital services. Regardless of ‘extreme’ demands, these materials can reach new standards without compromise.


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