Resiliency is a hot topic in design and construction today, motivated, in part, by the seemingly constant barrage of extreme weather events occurring across the country and around the world. And, sadly, these events seem as if they are happening more regularly—because they are. The Fourth National Climate Assessment (NCA4), released in November 2018, is a report mandated by Congress that “analyzes the effects of global change on the natural environment, agriculture, energy production and use, land and water resources, transportation, human health and welfare, human social systems, and biological diversity.” One of the key findings of NCA4 was that “the number of heat waves, heavy downpours, and major hurricanes has increased in the United States, and the strength of these events has increased too.” In addition, the report found the number of billion-dollar disasters, the term used for weather and climate-related disasters where overall damages or costs have reached or exceeded $1 billion, is on the rise as well.

From a design perspective, knowing that the occurrence of extreme weather events is on the rise gives designers good reason to look for ways to enhance the ability of a building, or a wider community, to prevent damage or recover from it more easily. This is the very idea of resilience.

All images courtesy of The National Terrazzo & Mosaic Association

Terrazzo is a poured-in-place flooring material that offers a unique blend of resilient and sustainable qualities.

As a strategy, resilience requires looking at almost every design decision through an extra lens. Resilience can be affected by building siting and layout. It requires extra levels of redundancy to reduce the potential single points of failure, and it increases the scrutiny under which various building systems and materials are selected. It may also create a greater demand for using materials that are inherently resilient and able to withstand exposure to the elements and be restored to like-new conditions. One example of a truly resilient material is terrazzo.

CASE STUDY: TERRAZZO & HURRICANE IKE

Terrazzo flooring was installed at the new Central Intermediate School in Ottawa, Illinois, because of its durability and longevity.

On September 13, 2008, Hurricane Ike made landfall near Galveston, Texas. This Category 2 hurricane was very large, with a diameter of its tropical storm force winds covering a total of 425 miles from the northwest to the southeast, and maximum sustained winds of 110 mph were recorded. According to the National Weather Service, “Hurricane Ike produced a damaging, destructive, and deadly storm surge across the upper Texas and southwest Louisiana coasts, and will likely end up being the third-costliest natural disaster in the United States behind Hurricane Katrina and Hurricane Andrew.”

The storm system that produced Hurricane Ike was also doing damage further north. It created heavy rains in Illinois, which caused widespread flooding of roads, creeks, drainage areas, open fields, low-lying areas, and basements. The National Weather Service explains, “This event impacted more people and resulted in more damage and fatalities than any event in this area in the past several years. Total estimated damages from the flooding are around $100 million.”

One of the buildings damaged by the flooding was Central Intermediate School in Ottawa, Illinois. When floodwaters filled the one-story, 90,000-square-foot structure, originally built in 1947, boilers, insulation, wiring, equipment, furniture, and doors were all destroyed. As the water receded and the damp interior began to dry out, the asbestos tile that had been used as flooring throughout much of the school started to detach. Despite the destruction that was found all around the building, the terrazzo floors that had been installed in the corridors when the school first opened remained perfectly intact.

With the building too damaged to repair, the district built a new Central Intermediate School. The new 97,000-square-foot building, designed by Green/Associates of Deerfield, Illinois, includes many of the latest amenities and an expanded presence of terrazzo in the corridors, cafetorium, and restrooms.

“The school district installed terrazzo again, in the new building, which is a testament to their recognition of the longevity and durability of this material,” says George Reigle, project architect at Green/Associates. “The reason most schools use terrazzo is because 50 to 75 years later it will still look the same as the day it was installed. Plus, it is low maintenance and durable, two qualities that are even more important in the day-to-day operation of a school than its ability to weather a flood.”

Introducing Terrazzo

Terrazzo is a poured-in-place or precast composite material that can be used as flooring or for wall treatments. While each installation is custom and distinct, terrazzo contains a blend of marble chips, quartz, granite, glass, and other types of aggregate, which is poured with a binder that is cementitious, epoxy, or a combination of both. In general, a terrazzo blend is roughly 75 percent aggregate (marble, granite, glass, pebble, porcelain, mother of pearl, sand, etc.) and 25 percent binder.

Terrazzo is difficult to damage, easy to repair, and available in an almost limitless number of colors and forms.

Divider strips are also part of every terrazzo surface. They are commonly used to separate different colors in the pattern and need to be placed at termination points (threshold of a door or where the flooring material changes) and at joints with excessive movement. The specific requirements for where the divider strips must be placed depend upon the type of terrazzo system being installed. The standard practice for cement-based terrazzo is to coordinate the placement of the divider strips with the joints found every 4 feet by 4 feet. This helps to counter the shrinkage and movement that can lead to cracking. Epoxy requires fewer strips and only true joints in the concrete must be honored. Divider strips can be selected in a variety of different material, including brass, plastic, zinc, and aluminum. The use of divider strips enables a terrazzo surface to contain ornate and intricate patterns, drawings, and designs.

If the binder is cementitious, the matrix is referred to as a cement matrix. If the binder is epoxy, the matrix is called an epoxy matrix. After the terrazzo is poured into place, it is cured. Then it is ground and polished smooth or otherwise finished to produce a uniformly textured surface.