Rubber Flooring Inspection
by Nick Gromicko
Rubber flooring is flooring made from either natural tree rubber or recycled rubber from vehicle tires. Long-touted for its slip-resistant qualities and durability in gyms, hospitals, factories, and other commercial buildings and establishments, rubber flooring is increasingly being installed in kitchens,
garages, playrooms and other residential applications. InterNACHI inspectors who perform residential and commercial inspections are likely to encounter rubber flooring at a diversity of venues, so knowing how to inspect for their condition and common defects can help them properly advise their clients.
A Brief History of Rubber
The ancient Mayans made rubber balls from plant and tree sap as long ago as 1600 BC. In the early 19th century, inventors Charles Goodyear and Nathaniel Hayward mixed sulfur and gum plastic with rubber under high heat in a process called vulcanization to create a more resilient product. Material shortages and demand for an even more durable rubber in the early 20th century led to the creation of synthetic rubber made entirely from man-made ingredients. Today, rubber used to make floors may be synthetic, recycled primarily from used car and truck tires, or natural, formed from extracted sap from the rubber tree Hevea brasiliensis.
Rubber Flooring Types and Applications
Manufacturers generally offer rubber flooring in the following two forms, which can be selected based on the desired location, installation requirements and appearance:
- tiles, which are easier to install than sheets because they come in smaller, individual pieces that can be moved and adjusted with less difficulty. Homeowners can choose a patterned look to make the seams less noticeable; and
- sheets, which boast greater moisture resistance because they have fewer seams, but they require more precise installation than rubber tiles. A professional installer may be required.
Additionally, rubber flooring may be attached to the floor in the following ways:
- glued down, in which the tiles or sheets are glued to the subfloor. Glued rubber flooring will stay in place and offers excellent durability;
- loose-lay, in which rubber flooring is attached to a smooth and clean flooring material with double-sided carpet tape; and
- interlocking, in which tiles lock into each other's pre-cut grooves. Installation is easy because no glue or tape is required, allowing them to be installed over many types of existing flooring.
Advantages of Rubber Flooring
Available in a huge array of patterns -- from speckled and interlocking to an inexpensive imitation of marble -- and in myriad colors, rubber affords homeowners great design flexibility. Designs may even be tailored to their application, such as the incorporation of bold lines to define pathways in a hospital.
Some other advantages of rubber over other types of flooring are as follows:
- Glue may not be required. Unlike most other flooring options, rubber tiles (depending on installation requirements) often require only carpet tape or no adhesive at all. This makes installation easier and protects indoor air quality from the odor and toxic compounds released by the glue required for installing other types of flooring products.
- Rubber flooring beats many other types of flooring in terms of longevity. When properly maintained, it can last the entire lifetime of a building. A urethane can be applied on top of the rubber to increase its durability and adds a glossy finish to the end product.
- Easy on the joints and comfortable to stand on for long periods of time, the inherent elasticity of rubber floors protects dropped breakables, unlike ceramic tiles and other alternatives. This quality also protects the floor against items that are dropped on it, while wooden, ceramic and linoleum floors are more easily chipped and scratched. Gym floors are generally made of rubber, which can protect users as well as absorb the impact from dropped dumbbells and other athletic equipment.
- Environmentally speaking, rubber flooring is low-impact. According to the U.S. Environmental Protection Agency, the U.S. generates approximately 290 million scrap auto tires per year, which accounts for 2% of all solid waste. Millions of scrap tires are buried or burned, filling the air and water with benzene, styrene, phenols, butadiene, and other toxic chemicals. Re-forming them into new tires is limited by product quality constraints, but they can easily be reused for rubber flooring, mitigating one of the largest and most problematic sources of waste. Rubber flooring can also be removed many years later and reinstalled in new buildings, thus eliminating the need to expend energy and deplete resources to manufacture new flooring material. Natural rubber is taken from trees, which are harvested responsibly and are a renewable resource.
- It is acoustically insulating. Rubber provides much better sound dampening than vinyl, tile, and other hard surfaces. It can even be installed beneath wooden floors to eliminate creaking.
- It is anti-static, so it won’t create static shocks during dry winters.
- Probably its greatest asset is that it's naturally slip-resistant. Rubber has a high coefficient of friction in wet and dry conditions relative to flooring alternatives, which makes it a good material around pools and other slippery areas. A surface textured in knobs will further increase slip resistance. To further illustrate this quality, consider the Olympics, where billions of eager eyes watch gymnasts leap and land on the sweat-laden floor. A slip under these circumstances could be disastrous, which is why Olympic floors are made of rubber.
Disadvantages of Rubber Flooring
InterNACHI inspectors, homeowners and commercial site managers should be aware of the following disadvantages and hazards associated with rubber flooring:
- flammability. All rubber is flammable, although various grades of fire-retardant rubber flooring are available, but the more flame-resistant materials are more expensive;
- lack of versatility. Carpet and wood floors may better suit traditional home décor, such as living room and bedroom applications;
- oxidation. Interactions with light, heat or certain metals will cause rubber to oxidize and become brittle;
- chalking. Exposure to inorganic fillers will deteriorate rubber flooring and cause it to become dull;
- softening and staining. This can be caused by interactions with oil, fatty acids, petroleum-based products, copper and solvents;
- loosening and lifting of seams. Rubber tiles are prone to moisture damage at the seams, which may allow additional moisture to penetrate into the subfloor. Rubber sheets protect better against moisture due to their lack of seams;
- odor. Rubber floors made from recycled tires have a characteristic smell that, while harmless, is found by some users to be unpleasant. The smell will lessen over time but will never go away completely. Problematic odors are especially prevalent in rubber floors manufactured outside the U.S. under low-quality standards, and they're glued together with strong-smelling urethane adhesives rather than the using the process of vulcanization. Some manufacturers recommend their recycled rubber floors not be installed in enclosed, unventilated spaces. Homeowners and commercial site owners can choose virgin rubber made from rubber trees, which is more expensive but lacks the odor associated with other rubber products; and
- off-gassing of volatile organic compounds (VOCs). While the Internet is flush with claims that the off-gassing from rubber flooring is limited to the harmless aforementioned odor, we at InterNACHI reviewed the only controlled study that attempted to measure the VOCs released by recycled rubber in floors. The 2010 study performed by California’s Public Health Institute titled Tire-Derived Rubber (TDR) Flooring Chemical Emissions Study presented the following findings:
- TDR and new rubber (NR) flooring products still emit a myriad of VOC chemicals, and their release is not uniform among the different products. A minority of products released excessive amounts of chemicals; and
- Xylene, butylated hydroxytoluene, ethylbenzene, toluene, formaldehyde and acetaldehyde were found in a range of products. Benzene and carbon disulfide were above the health threshold in one or two samples… [S]ome of the identified chemicals do not yet have health-based standards, making their health impacts difficult to assess.
Based on their findings, the study's authors make the following suggestions:
- TDR and NR flooring may be acceptable for indoor use, although products designated for exterior or exterior-interior use should generally be avoided indoors.
- Ample pre-occupancy “flush out” (or off-site pre-conditioning) is appropriate when TDR and NR flooring products are used indoors.
- Further refinement and testing of rubber-based products are necessary before these products can be promoted for wide use in most indoor environments.
Care and Maintenance
InterNACHI inspectors can pass along the following care and maintenance tips to their clients:
- Apply a protective finish coat soon after the floor is installed because the rubber surface will more readily scuff and attract soil during the first six to 12 months following installation. Do not apply an excessive number of coats of finish on soft rubber floors, as they can cause cracking and peeling. To ensure that this coating adheres to the newly installed flooring, it should be scrubbed with a mild pH stripper to remove any mold releases, paraffin, waxes, and other debris that may be left over from the manufacturing process. As the floor ages, it will harden and become easier to clean.
- Daily vacuuming is encouraged to keep dust to a minimum. Never clean a rubber floor with grit brushes or soiled cleaning pads. If the flooring cannot be fully cleaned with a vacuum, a damp mopping with a solution of mild soap and water will usually be sufficient. Never use acidic solvents or acetone because they may cause discoloration. Avoid the use of turpentine or petroleum-based cleaners, as they are likely to make the rubber sticky and can permanently damage the chemical composition of the floor. Do not let the cleaning solution stand on the rubber floor for long periods of time.
- Avoid the use of high-speed burnishers on rubber floors because they can cause burning, scalping or melted floor tiles.
- In a kitchen application, quickly clean spilled grease, and ask your flooring contractor about the grease-resistant properties of the floor.
In summary, rubber flooring is a durable flooring material commonly used in commercial venues that is increasingly being used in residential settings for its ease of installation, decreased maintenance requirements, and eco-friendliness. InterNACHI inspectors, homeowners and commercial site managers can make informed decisions regarding the qualities that make the material attractive or possibly unsuitable, depending on the application.