White Paper: Recommendation on Flooring Installation Failures
Published April 16, 2012
As an industry, we have had an ever-increasing number of flooring installation failures over the past decade. While we strive for success in all facets of our projects, flooring, specifically resilient flooring, has been a real challenge due to the never ending balance of form and function. It's fair to say most failures can be attributed to the use of innovative, emerging "Green" flooring products, water-based adhesives, lack of proper concrete substrate testing, lack of proper concrete substrate preparation, inadequate or inappropriate specifications, poor contractor performance, or a combination of these factors. In response we, as industry professionals, need to be prepared on each and every job for the variety of pre-existing environmental conditions that could exist regarding flooring and in most cases the concrete substrate. It is important to note, however, that these failures are not just limited to our region, but are occurring nationwide. The AIA-MBA Joint Committee would like to issue a simple, universal recommendation that provides the solution to avoiding flooring failures on every project; however, after lengthy investigation, we do not believe such a recommendation exists. What the Joint Committee recommends is that the construction team approaches a project knowing that flooring failures are a possibility. We want to raise the awareness on the issue and inform the A/E/C community about the improvement opportunities available with resilient flooring, their associated mastics, and concrete substrates.
Since the mid 1990's the flooring industry in the United States, like many other industries, has been forced to evolve to meet federal guidelines and standards. In November of 1990 the Clean Air Act was significantly amended when signed by President Bush, tightening standards in the quest to reduce air pollution and increase indoor air quality. As a result, the flooring industry was faced with the task of re-formulating the highly successful solvent-based flooring adhesives with ones which could meet the lower volatile organic compound (V.O.C.) regulations. The product borne out of this re-formulating process was the new generation of water-based adhesives. However, water-based adhesives did not hit the market overnight. Due to the projected poor success of the new water-based adhesives, solvent based adhesives were hoarded by installers for uninterrupted installations in the upcoming years. It wasn't until recently (last decade), when these back-stocked supplies were finally depleted, that resilient flooring failures became more prevalent.
While the changes within the mastic industry were evolving, design philosophy was also changing. Green design became more commonly known by the general public. Until the late 1970's, vinyl asbestos tile (V.A.T.) and linoleum were typically installed when a project required a resilient flooring material. As the harmful effects of asbestos became known, the industry transitioned to vinyl composition tile (V.C.T.). Both of these products contain a vinyl resin content of roughly 7-9% with the balance being made up of limestone and color pigments. This composition of ingredients afforded VAT & VCT the ability to wick moisture away from the concrete surface allowing for strong bond under a broad range of concrete slab conditions, even with a water-based adhesive. However, VCT, due to its visual characteristics has fallen out of favor with most designers, and today is typically reserved for more "back of house" type spaces. In a number of occupancy conditions monolithic flooring is also required to prevent fluids from reaching the substrate, such as in healthcare environments to aid in infection control.
Currently, most designers are utilizing a variety of sheet vinyl (S.V.) and luxury vinyl tile (L.V.T.) products to achieve design goals. These product types are comprised of about 75-90% vinyl content, which means that they do not have the same ability as VAT or VCT to wick moisture from a concrete slab containing an elevated moisture content. Furthermore, they are installed with water-based adhesives, which are susceptible to failure caused by moisture, high pH levels, or other contaminates in the concrete substrate.
With the use of water based adhesives came tighter environmental constraints as they apply to moisture. Moisture is an inherent part of concrete. It is always present, and can be found in concrete structures built thousands of years ago. Concrete exposed to moisture, either by high relative humidity or direct contact with water, will have a moisture content that is constantly changing. The solvent based adhesives were not as affected by moisture as the water based adhesives of today. Acceptable concrete substrate conditions for vinyl tile products can be 90-92% RH if moisture emissions are less than 3-5 lbs. per 1,000s.f./24hr period. However, sheet vinyl and other seamless flooring materials typically require the concrete substrate to contain no more than 75-85%RH with moisture emission ranging from less than 3-5 lbs. per 1,000s.f./24hr period. These are challenging and sometimes impossible levels to achieve with standard construction practices in new construction, especially when utilizing lightweight concrete for use in mid to high-rise projects where the presoaking of the stone aggregate is required for pumping purposes. In renovation work, existing concrete slabs may not only have high moisture content, but contamination problems as well. This contamination can occur through various sources including, but not limited to, cutting oil from pipe threaders, asbestos abatement, etc. Most owners choose chemical abatement over a mechanical means of asbestos abatement due to the time and the associated cost. Chemical abatement does minimize dust, noise, and cost, but chemical abatement contains petroleum sulfites that can reside in a concrete slab indefinitely. These petroleum sulfites will become absorbed into the concrete and will come back to the surface and react with the vinyl backing, breaking the bond and causing the flooring to delaminate. It is imperative that when asbestos is encountered, it is remediated properly with shot blasting or scarification in lieu of chemical abatement. Where you have tight areas, corners, or areas close to walls where these methods of abatement are needed, flexible shaft grinders can be utilized. Even though this process can be noisy, dusty, and costly, it gives the new floor covering the best opportunity for success.
In today's world of tracking mouse clicks and footsteps, time is everything. A multitude of shortcuts are taken to achieve today's project budgets and schedules. Most common of these shortcuts regarding flooring is the lack of concrete slab testing. It is in everyone's best interest that whenever possible, pre-construction testing be executed to determine the PH, RH, and moisture emission of the existing concrete slab. By doing so, you are able to prescribe a proactive solution to mitigate the problem prior to the commencement of construction and the creation of the project budget. This approach will minimize the need to increase the project's scope, schedule, and budget. Also, the design professional should consider including a basis for the contractor to seek additional time in the project schedule to address flooring issues.
As of today, there doesn't appear to be an immediate plausible solution. Until the advancement of technology and chemistry lead to the creation of an environmentally sound, sustainable mastic, we as an industry will need to remain vigilant in our quest for successful flooring installations. Architects and designers have a responsibility to insure that the written specifications are specific for the job, and that the language in the concrete specification is in line with the flooring specification for new and renovation work.
Although costly, the most conservative approach to ensure good floor adhesion seems to be the project to include a moisture membrane system. For now, it is imperative that the A/E/C community request unit costs as part of the contractor's bid for concrete slab moisture and/or contaminate mitigation. Specifically, unit costs shall be established for shot blasting, liquid applied moisture membrane, and cementitious underlayment during the design development phase of the project. In doing so, we are better prepared to address the unforeseen, ultimately providing the opportunity for greater project success. This will also make all parties aware of the potential cost implications during the budgeting phase of the project as well as avoid schedule delays and conflict between the design professional, constructor, and owner during the construction phase.
Recently in new construction, we have seen better success with the use of silica fume in the concrete mix design. This altered mix design, coupled with the use of a magnesium power troweled finish (increasing surface porosity), has yielded test results of 3.2 lbs. per 1,000s.f./24hr period. Time will tell if this is a viable solution to flooring adhesion failures. In researching alternate available mastics, we have also found that most flooring manufactures rely on a third party's mastic for the installation of their floor covering products. Some of these trowlable and spray mastics are warranted up to a PH of 10, and 12lbs. of moisture emission per 1,000s.f./24hr period. For the time being, the important thing is for the design professionals and constructors to make the owner aware of the issue and the associated costs.
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