Rubber Underfoot

Offering one of the best life-cycle values, not to mention ease of maintenance, durability, support, good acoustics and slip resistance, rubber is becoming an increasingly popular sustainable flooring choice
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A For Acoustic

Moving on to acoustics, the unique properties of rubber also make it a phenomenal sound-absorbent material.

“With NRC values ranging from 0.05 to 0.15, rubber flooring can contribute to creating a comfortable acoustic space significantly more than other hard surfaces such as tile or terrazzo,” reports Sharon Ho, INCE, acoustic engineer, ECORE.

In addition, its natural elasticity reduces sounds from footsteps and dropped items, as well as dulling sound transmission between floors.

In fact, hospitals and office buildings located next to noisy warehouses have been known to specify rubber flooring for acoustical purposes, and according to Witte, some rubber flooring products even offer the same acoustical performance as carpet, as verified by testing.

“Rubber is among the best materials to use for sound and vibration isolation,” confirms Ho. “Rubber floor underlayments provide a resilient break between otherwise stiff elements and connections such as concrete slabs, ceramic tile thinsets and thick nails. This makes a floorceiling assembly less efficient at transmitting sound and vibrations from impacts on the flooring above to the space below.”

Generally speaking, the testing procedure involves using a tapping machine to produce a series of impacts on the floor and then measuring sound transmission levels to the room below. In terms of published results, some studies are performed on rubber with a wood subfloor, per ISO 140-8, and others use concrete subfloors, per ASTM E2179.

Naturally, Witte points out that the use of thicker rubber flooring-i.e., 3mm or 2mm-along with an acoustical backing will enable higher acoustical performance.

As such, Bostock reports that noraplan acoustic rubber flooring has been tested to reduce footfall sound by up to 20 dB for a perceived reduction of 75 percent.

Recycled Rubber

Not only are many rubber flooring products made from assorted recycled materials, but many have a number of interesting end-of-life applications as well.

For example, nora products reuse production scraps such as die-cut trim and sanding dust, but perhaps even more interesting is the fact that they are then recycled and used in landing mats, industrial and stable mats, and coverings for sports arenas.

“They are also granulated and become part of the raw material base of new rubber flooring products as high-quality fillers and decorative color speckles,” says Bostock. “And since they contain no toxic substances, nora floors can be disposed in landfills.”

Meanwhile, ECORE runs a Redeux Reclamation Program and Johnsonite has a similar ReStart program which collects uninstalled commercial rubber-as well as vinyl and linoleum tile, sheet, wall base, accessory and tread-cutting-so that the materials can be repurposed for other products or uses. Johnsonite will also take back unglued rubber tiles from a job site and send them on to a supplier who grinds them to dust for use as filler in auto parts.

Such take-back programs are important to end-users such as Christian Miller, CFM, director, property management, YMCA of Greater New York, who manages 25 YMCAs in the New York metropolitan area. In these facilities, rubber flooring is used in the multipurpose rooms, cardiovascular centers, weight rooms, wet area locker room spaces and outdoor park areas. In fact, a big selling point for Miller is when companies take back and recycle the YMCA’s used rubber.

As far as recycled content in Johnsonsite products, Visintin explains that the company’s CorkTones Rubber Tile and Treads contain 2.5 percent rapidly renewable cork taken from pre-consumer waste stream materials and the company’s Eco- Shell with Cork Rubber Tiles and Treads contains dust made from the annual walnut harvest.

“Additionally, our SlideLock modular flooring installs easily without adhesive and can be quickly removed, replaced, repurposed or transported so flooring doesn’t have to change just because a space or location does,” he notes.

Similarly, ECORE’s rubber flooring is made from a reclaimed waste stream, which is mostly tires, but also incorporates post-industrial manufactured flooring and roofing membranes. In fact, ECORE claims to be North America’s largest consumer of recycled scrap-tire rubber, reusing more than 80 million pounds of material each year to produce rubber flooring.

Mostly utilizing tractor trailer tires, the old treads are grinded, screened and separated to remove contaminants. The metal debris is collected and sold for reuse in other applications, while the remaining rubber crumb is used for new flooring products.

Disputing the claim that there are IAQ risks associated with using reclaimed waste material, Barber states, “This is simply not the case. While we are taking an unknown waste stream and reusing it, the risks associated with this are negligible. We have learned to refine recycled rubber to the highest standard.”

In terms of rubber itself, Capo and McLaughin point out that the process of removing sap from the tree doesn’t require cutting down the tree, nor does it damage the tree. On the contrary, rubber trees are a sustainable, rapidly renewable resource that naturally generate more sap.

As noted, rubber flooring is often chopped and shredded and then used in a variety of ways such as landscaping mulches, playground surfacing and rubber crumb for athletic fields.

“When used as landscaping mulch, recycled rubber flooring is considered safe and harmless to plants. It also lasts longer than organic materials. And compared to traditional landscaping rock, it provides more volume with less than half the weight. This reduces shipping costs and labor load,” say Capo and McLaughlin. “In addition to the above, recycled rubber flooring is also being combined with re-binders to make Olympic weights and concrete block for pavers.”

Buyer Beware

As wonderful as rubber flooring is, there are a few sticky points that specifiers and end-users must be aware of.

For example, because rubber tends to be a thicker floor, Miller points out that this will sometimes require adjusting the floor’s thresholds. “In some cases, we purchased edges in yellow because of the floor height difference, so it’s not a tripping hazard.”

And although some rubber flooring doesn’t require glue for installation, for the products that do, the process of removal can be challenging. “When you pull it up, it tends to separate and you have pieces that don’t come off completely, which ultimately requires a good floor scraping,” reports Miller.

Furthermore, White points out that sharp or heavy objects can dent the rubber and cause it to split, and once you have to start repairing portions of the floor, this can be costly. Similarly, some cleaning chemicals and metal floor scrapers can also damage the floor.

“You need to properly train staff to maintain this product because it can be damaged easily and all it takes is one little mistake,” she advises.

Offering some additional advice, the International Association of Certified Home Inspectors (InterNACHI) notes the following rubber limitations:

  • Rubber is a flammable material and although different grades of fire-retardant rubber flooring are available, they are more expensive products.
  • Interactions with light, heat and some metals will cause rubber to oxidize and turn brittle.
  • Exposure to inorganic fillers will deteriorate rubber flooring and dull its color.
  • Interactions with oil, fatty acids, petroleum-based products, copper and solvents can cause softening and staining.
  • Rubber tiles are prone to moisture damage at the seams, which may allow additional moisture to penetrate into the subfloor. Rubber floors made from recycled tires have a certain odor which is harmless, but to some may be unpleasant. Some manufacturers recommend their recycled rubber floors not be installed in enclosed, unventilated spaces.

Ecore Commercial Flooring Ecore transforms reclaimed waste into unique surfaces that make people's lives better every day. Can a floor do more? Yes. Ecore products that incorporate its patented its tru technology offer safety, ergonomics, and excellent acoustics, in addition to being sustainable, durable, and easy to install and maintain.


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Originally published in Environmental Design + Construction