Green stone and tile recommendations

Like all building materials, stone and tile products have both beneficial and negative environmental aspects. With respect to indoor air quality, people with serious allergies or other chronic respiratory ailments better tolerate stone and tile products because they release few, if any, emissions.

Like all building materials, stone and tile products have both beneficial and negative environmental aspects. One of the strongest positives is that stone, tile, and grout (once it has cured) release few, if any, VOCs or other problematic air emissions. People with serious allergies or other chronic respiratory ailments often tolerate these materials better than other finish materials. In addition, stone and tile can be thoroughly cleaned and sealed, reducing the potential for build-up of molds, dust mites, and other allergy-causing agents.

It should be noted, however, that all earth-based products (stone, tile, masonry, concrete, gypsum wallboard, etc.) contain traces of radon, a radioactive gas that occurs naturally in soil and rock throughout the U.S. and elsewhere. There is currently some discussion within industry circles as to whether the levels of this off-gassing in stone products, such as granite, are problematic. The EPA's most recent view (August 2008) is that the amount of radon emitted by earth-based building materials is generally very small compared to typical background levels of radon present indoors and outdoors. A few stone products emit more significant levels of radon—it depends on the quarry—but they are rare. If you are concerned about a particular product, have it tested.

Another important consideration is the relative durability of a product, and here stone and tile are superior to other finish materials. The durability of stone and tile varies according to type and depends upon each material's hardness and resistance to wear by abrasive substances, water, and physical impacts. With proper maintenance (periodic grout repair and surface sealants where recommended by the manufacturer), these materials last a very long time, from 50 to hundreds of years. This durability can reduce long-term maintenance and replacement costs to such a degree that life cycle costs may actually be less than those associated with relatively inexpensive products, especially in areas of high wear where periodic replacement (averaging about every seven years) is the norm. The environmental benefits from this durability include a reduction in the local impacts of resource extraction and a savings in the energy consumed over time for manufacturing, reinstallation, and disposal.

However, stone and tile products, because of their weight, require more energy for transportation than other finish materials for floors and walls, producing greater contributions to global warming. For that reason, from an environmental standpoint it is definitely preferable to buy products that are quarried and manufactured relatively close to the building site. The extraction of raw materials does have an environmental impact, but quarrying operations are typically smaller in scale and the impacts are more contained than, for example, large coal or metallic ore mining operations.

Stone
Stone varieties most commonly used for construction include granite, marble, quartzite, limestone, slate, shale, sandstone, soapstone, and travertine. Materials that have low water absorption rates (most granites, marbles, quartzites, and slates, and some limestones) can better resist freeze-thaw cycles in climates where that is an issue. Marble surfaces degrade when exposed to acids, so this material is not a good choice for countertops or building exteriors in smoggy environments. From a design standpoint, stone, with its natural appearance and richness of color and texture, can become a strong focus within a design that has a naturalistic aesthetic. 

Terrazzo
Terrazzo consists of small colored chips (stone, masonry, concrete, tile, glass, etc.) bound together by an adhesive matrix that is either concrete or epoxy-based. Installers can incorporate recycled materials such as glass into the matrix, improving the product's environmental profile. Epoxy-resin binders are not completely free of emissions during the cure period, but most people tolerate the cured product well. Because of the wide range of materials and colors available for both the matrix and binder, terrazzo lends itself to diverse aesthetic effects. It can be designed as a subtly textured background surface, as a major focal point, or as anything in between.

Ceramic Tile
Like stone, ceramic tile is extremely durable. Porcelain tile, originally named for the porcelain clays that it was manufactured from, is now defined as any ceramic tile with a low water absorption factor (under .5). Ceramic tile is more energy-intensive to produce than stone or other flooring alternatives (wood and bamboo, for instance), so it is not inherently a green product from an energy standpoint, but this is offset to some extent by the greater longevity of the product. There are few specifically green ceramic tile products, although most manufacturers recycle their production clay wastes. Ceramic tile is available in a wide range of colors, textures, and patterns, glazed or unglazed, so the design possibilities are endless.

Glass Tile
Even though glass tiles have been around since before the Roman era, many new products incorporating pre- or post-consumer recycled glass have recently become available. Some of these tiles have the appearance (and durability) of ceramic tile while others look (and wear) more like traditional glass tiles, where abrasions tend to become apparent more quickly. Recycled glass tiles are more energy-efficient to manufacture than ceramic tile, utilizing about one-half as much energy, whereas cast-glass tiles require about twice as much energy to produce as ceramic tiles. Although glass tile does not have as wide a range of colors, textures, and patterns as ceramic tile, it often has an appealing translucency and softness of color and texture that cannot be found in ceramic tile.

Installation
Environmental considerations should be addressed during the installation phase of a project in order to protect the health of construction workers and the health of the building's occupants. Toxic air emissions (from uncured adhesives, grout, and terrazzo resins) and airborne irritants such as construction dust should be reduced as much as possible or avoided altogether, thereby reducing the potential for absorption into porous building materials (such as gypboard, wood, carpets, and fabrics) that could later be re-released into the enclosed living spaces.

First, select adhesives and sealants that are not only appropriate for the intended purpose but that also contain minimal VOCs or other toxic emissions. Secondly, specify that your contractor do their cutting and grinding of tile and stone outdoors as much as is reasonably possible. Also, note that grout may stain or trap dirt and mold spores if not properly sealed.

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