Resilient and Sustainable Terrazzo Flooring

A closer look at how this material survives floods and supports green design
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Sponsored by The National Terrazzo & Mosaic Association
By Jeanette Fitzgerald Pitts
Long Lasting

Terrazzo can last for more than 100 years. Does that sound like marketing fodder? It is not. As proof, there are four courthouses in the Pacific Northwest that have recently celebrated their centennial, and each of them features terrazzo flooring. Two of the four historic buildings are in Washington. Spokane’s Federal Building and U.S. Post Office turned 100 in 2009. The Tacoma Union Station got its 100th candle in 2011. In Oregon, Portland’s Pioneer Courthouse was completed in 1875 and is now the second-oldest courthouse west of the Mississippi. The terrazzo floors were installed in 1905 and remain in use today. The only signs of age in the aged floors are spots that are slightly worn down in front of the post office window and a couple of settlement cracks that occurred as the building settled into its bones over the past century. Yakima’s William O. Douglas Courthouse, and its terrazzo flooring, turned 100 in 2012.

The original terrazzo floors at the Tacoma Union Station in Washington turned 100 in 2011 and are still in use today.

“Terrazzo is a very durable, beautiful substance for buildings with high traffic,” explains Rebecca Nielsen, Historic Preservation Program specialist and LEED Accredited Professional with the U.S. General Services Administration (GSA) in Auburn, Washington. She oversees twenty historic register federal buildings in the Pacific Northwest. “Terrazzo was obviously a good choice because 100 years later, we are still using it,” she adds.

Over the years, the floors have required repairs to fix chips or minor cracks and an occasional resealing, along with routine maintenance to keep them functional. “The terrazzo is in great shape,” Nielsen continues. “We fix up the cracks and we maintain it. There is certainly no reason to replace it. It is working just fine.”

How Terrazzo Survived Hurricane Katrina

When Hurricane Katrina tore through New Orleans on August 29, 2005, it became the costliest natural disaster in U.S. history. Property damage was estimated at $81.2 billion. Eighty percent of the city and vast sections of neighboring areas were flooded when the levees and flood walls failed. Saltwater surged in, picking up mud, waste, sewage, petroleum, chemicals, and acids, and then sat in stagnated pools for weeks.

After Hurricane Katrina, the original terrazzo floors in the New Orleans Lakefront Airport generally remained intact and were restored with a light sanding and polish.

The New Orleans Lakefront Airport, located on Lake Pontchartrain, was one of the buildings that sustained incredible damage during the storm. Originally built in 1934 in the Art Deco style, this airport was deemed “the air hub of the Americas” and was considered a wonder of architecture and decor. When Katrina pushed the lake water inland, it submerged the airport in 4 feet of water. Furniture and equipment floated around the ground level.

After the water subsided, the $17-million post-Katrina restoration began. “There were massive property losses at the Lakefront Airport,” reports architect Alton Davis of Richard Lambert Consultants, the leader of the architectural team tasked with the renovation. “None of the drywall that had been installed since the 1960s survived. Even the grid behind the plaster had rusted. Most of the ground-level flooring that had been trapped underwater was destroyed as well—wood, carpet, ceramic tile, and vinyl composite tile (VCT). The terrazzo floors, however, generally remained intact. There were a few places where heavy equipment had gouged or cracked the floor, and that needed to be repaired, but most of the flooring needed no more than a light sanding and polish to be restored.”

The terrazzo at the airport was not the only terrazzo flooring found intact after Katrina. In fact, terrazzo floors around the city had survived their extended submersion and were able to be restored. This was the case for the terrazzo floors at the city’s convention center, train station, and a number of old churches and schools. Clyde Martin of American Tile & Terrazzo Co. of Metaire, Louisiana, was the contractor at the Lakefront Airport restoration and was heavily involved with many of the other terrazzo restorations throughout the city. “In one church, the roof and stained-glass windows were destroyed. The statues reduced to rubble. All that could be saved were the structural steel, a few brick walls, and the terrazzo floors,” he reports.

The destruction of Katrina highlighted the toughness of terrazzo flooring. “There is not another flooring choice that held up to the flood,” Martin says. “Water destroys carpet and vinyl tiles. Ceramic tile is easily broken by falling furniture and equipment, and it is hard to patch because of UV discoloration. If the tile grout is stained, it is more cost-effective to start over.”

In the flurry of rebuilding activity, a resilience-focused, flood-proofing trend emerged. Designers leaned on the materials that had proven their ability to survive the extremes and regularly chose metal roofs, concrete block, structural steel, and terrazzo floors for the new construction projects around the city.

“Moisture does not hurt cement. Some bathtubs are made from cement,” explains Gary French, technical director at the National Terrazzo & Mosaic Association. “If the water stays on top of the slab, the terrazzo flooring surface can be restored, oftentimes with just a little light sanding and polish. Even if the structure collapsed and the terrazzo floors were chipped or gouged when large equipment fell on them, the floors can be ground down and repaired.”

While many designers are aware of this material’s durability, seeing how it performed during Katrina and the post-Katrina reconstruction was a powerful reminder for many on just how tough terrazzo is. This sentiment was shared by Alton Davis as he discussed his experience during the restoration of the Lakefront Airport. “Katrina just reemphasized what I already knew about terrazzo. When they tear down the building, it will still be there. If the building lasts hundreds of years, the terrazzo will last hundreds of years.”

The Inherent Sustainability of Terrazzo

Beyond its natural resiliency, terrazzo also has many qualities that allow it to support several important tenets of sustainable design. While first focused on improving the energy efficiency of the built environment, green design considerations have evolved, now placing an increasingly stringent expectation around the material efficiency of the products incorporated into the built environment.

“Terrazzo, as a material, satisfies many green building concerns in terms of its makeup, longevity, and ability to protect the integrity of the indoor environmental quality of a space,” explains Edward Balkin, architect and director of design at Coover-Clark and Associates. “Specifying terrazzo flooring on a project can help to achieve recycled content thresholds, improve construction waste management efforts, and create healthy indoor environments, as its adhesives and sealants are all considered low-emitting materials.”

Terrazzo has a number of qualities that make it well-suited for projects with sustainable design goals. It can contribute toward recycled content thresholds, improve construction management efforts, and help create healthy indoor environments.

Recycled Content

There is an old saying in sustainable design that the most sustainable building is the one that is already built. It underlines the importance of the material cost that is incurred in the creation of something brand new. There is an environmental value to fixing something that exists, instead of scrapping it entirely and replacing it with something else. This, in a way, helps to explain the appeal of choosing products that contain recycled content. These products divert something from the landfill. They effectively repurpose some used materials into a new useful life and reduce the use of precious virgin materials and resources.

Terrazzo was originally created in Italy more than 500 years ago by Venetian workers searching for ways to use discarded marble remnants from slab marble processing. Used marble chips were tossed into cement, and the resulting speckled or spotted pattern that emerged on the cured and hardened surface was referred to as terrazzo. Today, terrazzo continues to incorporate recycled content in the form of the aggregates used in the matrix. Several glass aggregate suppliers are currently providing post-consumer recycled glass to the marketplace. A floor incorporating 100 percent recycled glass aggregate could contain as much as 75 percent recycled raw material by volume.

Several slab marble and granite quarries offer supplies of post-industrial stone left from slab granite and marble processing. Terrazzo can also incorporate stone or marble that has been salvaged from other buildings and re-crushed and sieved for use in the flooring. Pieces of pre-consumer porcelain and recycled concrete can also be used in a terrazzo floor. If plastic chips are selected as part of the matrix, they may contain as much as 20 percent recycled plastic. Aluminum divider strips may also contain recycled metal.

Regional Ingredients

Another material consideration gaining traction in the industry is the promotion of regional sourcing. The goal is to reduce the environmental impact that is made by transporting the building materials and products to the job site. The idea is that designers should attempt to use products manufactured or extracted within the region, as they require less energy to physically transport them to the site. Regional sourcing also supports the use of indigenous resources.

Terrazzo can be specified and supplied in a way that supports this region-centric approach. The variety of aggregates, as well as the cement and epoxy binders, are available throughout many areas of the United States. Not only can the material used within the terrazzo be sourced locally, but the distinct and regionally sensitive aggregates can create a flooring surface that has a greater connection with the space. For example, in regions where there is a lot of granite, granite can be incorporated into the terrazzo flooring to showcase a local resource. There are many manufacturers, suppliers, and distributors of terrazzo strategically located throughout the country.

 

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Originally published in Architectural Record
Originally published in November 2019

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