Whether protecting ancient artifacts or housing thousands of servers that store and transmit sensitive data to inform tomorrow’s decisions, a building’s mission is what makes it critical. As such, materials used in some of the world’s most iconic structures are now available to protect America’s mission critical buildings.

When it comes to protecting the mission of these buildings, the roof — especially the insulation inside the roof — is critical to the continuous operation of the processes inside. Across the various components of the building enclosure, the roof provides powerful protection for the people and systems within as it defends against varied external threats. The tyranny of time, the assault of nature’s elements, and the requirements of sustainability criteria all weigh on the assembly that “covers it all” — the commercial roof. The trusted performance of the roof takes on an even higher level of importance when it is viewed in context with two of the world’s most precious commodities: time and money. A widely published report by the Ponemon Institute estimates the cost of a data center outage at $9,000 per minute. Losses are not limited to data centers. A recent lightning strike on the Moody Music Building at the University of Alabama ignited the roof insulation, causing a fire that burned for over 12 hours and required more than 1 million gallons of water to extinguish. The building requires a complete renovation with no backup in the interim.

To meet the unique demands of mission critical buildings and the high-value processes they house, cellular glass insulation is a high-performing choice for specifiers of mission critical roofs. While relatively novel in U.S. buildings, cellular glass insulation has long been used in some of Europe’s most popular structures, including the Acropolis Museum in Athens and the Swiss National Museum in Zurich. For decades, cellular glass has stood up to demands, not just in these high-profile buildings, but in the roofs of structures with a decidedly lower profile, such as the Jardine Water Purification plant in Chicago.

What makes cellular glass insulation so unique? In a recent episode of The Thought Cloud podcast, several questions that commonly arise when designing roofs for mission critical buildings were discussed — specifically regarding data centers. The properties that differentiate cellular glass from other building materials were also explored. Based on that conversation, here are five questions that can help inform the specification of cellular glass in mission critical roofs.


  1. What is cellular glass insulation and what is it made of?

The performance of any building material is a function not just of its parts, but of the manufacturing processes used in the ingredient’s manufacture. Product and process combine to make a material greater than the sum of its parts. True to its name, cellular glass is a rigid foam comprised of millions of hermetically sealed glass bubbles. It is comprised entirely of glass, with about 60% of contents sourced from recycled glass. The glass is blended with other ingredients to form a molten compound, which is crushed and heated. Through a natural process of oxidation, a glass matrix comprised of sealed, watertight bubbles is formed.

  1. What makes cellular glass insulation ideal for mission critical roofs?

In one word — redundancy. Cellular glass provides a backup layer of protection against any breaks or tears in the roofing membrane. Under the stress of time, the weight of rooftop equipment (solar arrays, HVAC equipment, vegetative roofs, etc.) can make even the highest-performing membranes leak. However, cellular glass insulation provides a second watertight level of protection.

  1. How does cellular glass insulation work in context with the rest of the roofing assembly?

Used in a protected roof membrane assembly (PRMA), the waterproofing membrane is applied first with the insulation atop the waterproofing and then covered by a surface covering, such as a concrete topping slab, pavers, or vegetation. A unique aspect of cellular glass insulation is that the material is embedded into the waterproofing itself while the waterproofing is still wet. Next, subsequent layers of waterproofing top off the insulation, providing a watertight assembly that serves as a barrier to not just water but also vapors. And as every data center manager knows, humidity in liquid or vapor form presents a hazard. The high compressive strength of cellular glass is complemented by strong dimensional stability, resulting in less stress on the structure and on the membrane over its lifetime.

  1. How strong is cellular glass?

The impressive compressive strength, cellular glass insulation allows it to sustain high loads without deflecting under pressure. As more and more rooftops become real estate for solar arrays, HVAC equipment, and vegetation, the time, effort and expense required to remove these materials to remediate a problem on the roof increases. Roof systems comprising cellular glass insulation are built to stand the pressures of time. A good example of this resilience is the Jardine Water Treatment Plant in Chicago. Built on the shoreline of Lake Michigan, the insulation stood the test of Chicago’s infamous winter climate for more than a half-century. When the roof was replaced due to problems with the structural deck, the insulation was still in excellent condition.

  1. What other performance benefits does cellular glass present to specifiers?

Beyond compressive strength and outstanding resistance to moisture, cellular glass brings other benefits to mission critical rooftops. At a time when designers and building owners alike are seeking sustainable options for their high-performing buildings, ingredients such as sand/glass can help contribute toward overall green building goals. Additionally, cellular glass contains no flame retardants, blowing agents, or binders. And as every building product is contingent upon its proper installation, cellular glass comes in a variety of thicknesses and shapes, requires no special tools, and is easy to install on the job site. The material can be attached via a variety of adhering agents, including hot asphalts as well as cold adhesives.

Cellular glass insulation is not a new material; it has proven its ability to protect some of the world’s most precious rooftops. And as designers are seeking trusted and proven materials, it brings an extra measure of confidence to protect the people and processes inside mission critical data centers.