Claudia Lezell

As floor covering and related materials evolve, the design, build, maintenance, and related industries face a major conundrum. Slip, trip, fall, and hard surface floor-covering claims have now soared into billions of dollars. Is a floor-failure epidemic inevitable? Root-Cause Analysis Problems arise when standards (or lack thereof) conflict with specification and product performance. A paradox can occur when over-expectation and misspecification outweighs material performance capacity. With recent advancements in technology, we have entered an exciting, yet challenging and sometimes frustrating, time. Because of new technologies and sustainability efforts, materials are becoming stronger, better made, more chemically resistant, biodegradable, and recyclable. But these positive changes come with unintended consequences and conditions that are created from complacency with the status quo, naiveté, and unfortunately, subject-matter ignorance. The Costly Outcome Despite ongoing efforts to educate, certify, and revise or develop standards, as advances in flooring materials continue to grow in popularity, the cost of claims rise. A colleague who saw his claim value climb into the tens of millions of dollars is just one example of how drastic these cost increases can be. Big numbers. Big challenges. The last generation saw a surge in construction demand. While this surge had a positive effect on our economy, it had a downside that included the occassional use of substandard products; material shortages; sloppy or too broad specifications; devalued engineering to accommodate cheap, fast-track construction; sloppy workmanship, such as rushing concrete placement and covering the material too quickly with floorcovering; and ineffective job staging. Add to this the complicating factors that more severe weather conditions invite, and you have a prescription for product failure and moisture intrusion that can result in mold and indoor air quality problems. This can cause big problems down the line for facility managers and their staff. For floors, the bottom line is this: A one-size-fits-all construction specification for below-grade, on-grade, and above-grade floor-covering installation does not work. On the flip side, implementing inspections and consulting support can help to prevent over-expectation of product, lower-quality workmanship, and misconception of product performance. Overall, it will help to ensure a longer lifespan of your floors. Floor System Failure: Who Done It? By the time a floor failure makes itself known, it can take more time to undo the damage from those who are more interested in proving it wasn’t their fault than it does to work with a forensic team to solve the problem. Being the last one in requires time, testing, and expense to get to the bottom of it. A repeating pattern in this type of analysis is often referred to as the “domino effect.” During the investigation process, one answer usually leads to another question, and the individual components of the failure weigh on top of one another like a set of falling dominoes. Image 1: Schematic representation of the components in a slab on ground floor system.Image courtesy of Portland Cement Association and National Ready-Mix Concrete Association Start From the Ground Up When trying to pinpoint the root cause of flooring failure, making a literal start from the ground up is a good idea. Let’s start by exploring soil, a term that can be defined in many ways. A geologist defines “soil” as an altered rock. A soil engineer will describe it as the material that supports or loads a structure at its base. Someone else might define it as a combination of boulders, gravel, sand, silt, clay, and organic matter. Soil provides support for the structure, shapes and forms the final grade, and in some instances, provides disposal for sewage. According to the PCA Soil Primer, a booklet published by the Portland Cement Association, “The moisture or water content of a soil is normally a percentage of the oven dry-weight of the soil, as tested by ASM D2216 or AASHTO T265.” Soil moisture is of three different types: gravitational water, capillary water, and hygroscopic water. Soil type, size, compaction, moisture content, chemistry, drainage, or even testing can play a role as one of the culprits in floor failure. For instance, if a soil is not compacted well or varies in chemistry throughout the site, it can impact the concrete floor flatness (FF) or floor levelness (FL), causing undulations, which can affect some or all of the components of the entire floor system. Image 2Courtesy of the American Concrete Institute The Role of the Vaper Retarder Soil and transmission of moisture in soil can seriously affect concrete and flooring by eliminating or degenerating the vapor retarder and using a vapor retarder with a lower permanence rate. According to Howard M. Kanare, in the book Concrete Floors and Moisture, “Vapor retarders must have a permanence rating less than 0.3 perms, according to ASTM E1745. There is no standard specification for vapor barrier compared to vapor retarder. However, ACI 302.1R states, ‘True vapor barriers and products have a permanence (water-vapor transmission) rating of 0.00 perms when tested in accordance with ASTM E96’.” It is generally accepted in the construction industry that a material with a permanence rating of less than 0.01 perms is considered to have a vapor barrier. When dealing with concrete flooring, even if a vapor retarder is present, it sometimes won’t meet the criteria of what the ASTM E1745 states regarding vapor retarders. In many instances, mil thickness is mistaken for permanence. Additionally, if a vapor retarder is used with no barrier because of expense, it sometimes does not conform to the adaptation of installation requirements made to ACI 302.1R in 2004. Image 2 shows a flow chart that was adapted from ACI 302.1R-04 in Concrete Floors and Moisture. The chart description says, “It permits omitting vapor retarder for floors without floor coverings where humidity will not be controlled, such as unconditioned warehouse space.” However, it also further states that “adaptive reuse and installation of flooring in such spaces often leads to flooring problems due to subslab moisture. Therefore, vapor retarders should be considered for use under all floor slabs.” If a building owner or facility manager assumes there is

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Claudia Lezell

Co-Founder, Flooring Technology Institute

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