Luxury Vinyl Tile and Plank Flooring
Design, Selection and Installation Considerations – September, 2021
George Donnelly Testing and Inspections
1 Curso Lane, Hot Springs Village, AR 71909-3723
Luxury Vinyl Tile (LVT) and Luxury Vinyl Plank (LVP) are marketing terms with little practical significance. Product make-up may be described as solid vinyl (SVT), vinyl composition (VCT), stone plastic composite (SPC), wood plastic composite (WPC) or offer descriptions that are dissimilar to any of these. The intent of this paper is neither to promote nor denigrate any individual product, manufacturer or distribution chain. However, there have been numerous issues with products labeled LVT or LVP across the United States. The subjects enumerated below reflect conditions this agency has investigated or reviewed. Issues or claims have included product cupping at edges, doming in tile centers, excessive expansion or shrinkage, partial loss of bond and plasticizer migration. This paper is therefor, intended to visit subject matter that should be evaluated by owners, design professionals, construction managers and installation contractors before product selection and/or installation.
There are two (2) significant ASTM standards intended to help create uniformity of product performance criteria and aid specifiers in product selection of vinyl based tile flooring.
ASTM F 1700 - Standard Speciﬁcation for Solid Vinyl Floor Tile
Solid Vinyl Tile is defined in ASTM F141 as:
“A resilient tile ﬂooring composed of binder, ﬁllers and pigments compounded with suitable stabilizers and processing aids. The binder consists of polymers and/or
copolymers of vinyl chloride, other modifying resins, and plasticizers which comprise at least 34 % by weight of the ﬁnished tile. The polymers and copolymers of vinyl chloride comprise at least 60 % of the weight of the binder.”*
ASTM F1066 - Standard Speciﬁcation for Vinyl Composition Floor Tile
Vinyl Composition Tile is defined in ASTM F141 as:
“A resilient ﬂoor covering composed of binder, ﬁllers, and pigments. The binder shall
consist of one or more resins of poly (vinyl chloride), or vinyl chloride copolymers, or both, compounded with suitable plasticizers and stabilizers. Other polymeric resins may
be incorporated as part of the binder.”*
*Definitions taken from ASTM F141Standard Terminology Relating to Resilient Floor Coverings
Product offerings advertised under the marketing terms LVT or LVP, include products that list compliance with ASTM F1066, or ASTM F1700, or in some cases make no reference to either or any ASTM standard product specification. Within both standard specifications physical characteristics and performance criteria are demanded. However, some product data sheets omit specific test result data, which should be required if a product is to be considered. Specifiers need to critically review product data sheets and the information presented or missing.
Most major floor covering manufacturers in the United States have entered the floor covering market with LVT/LVP offerings. However, many do not manufacture the products they label and sell. A 2019 article in Floor Covering Weekly noted “approximately 75% of LVT sold in the U.S. is imported, and that 83% of that total is from China”. A recent visit to the website “made-in-china.com” revealed a list of 336 manufacturers offering LVT, SPC and WPC product for sale both within China and for export. Second to China the next major supplier/exporter of product to the U.S. is Korea. While the floor covering industry is expanding U.S. production, it is the opinion of the author that product source is a question worth asking and information worth considering.
As noted in the opening paragraph, physical and aesthetic distresses are reported across the United States and have become too common in this product category. In reviewing distress claims investigated by this agency or reported to the author, it is my opinion that claims are primarily attributable to five causations.
1. Dimensional instability of product in a given environment. While, this may sound confusing, a review of product installation guides offers insight. There are LVT/LVP product installation guides that list “the post installation temperature range allowed is an ambient temperature of 32°F and 100°F”. Another guide suggests installation in spaces that might not be climate controlled for extended periods of the year “is allowed in an ambient room temperature between -25°F and 155°F”. A far broader spectrum of products list acceptable post-installation environments limited to minimum temperature between 55°F and 65°F with maximum allowable temperature of 85°F. More than one manufacturer suggests one of these or similar warnings “The performance of the flooring material and adhesives can be adversely affected outside this temperature range.” Or “Maintain room temperature between 65-85°F for optimum performance”
There are at least two points that this information should clearly indicate;
First, installation of these products must be limited to spaces that are fully acclimated to service temperature and service relative humidity in enclosed spaces with fully functional HVAC systems. Schedules that require floor covering installation under adverse ambient conditions must be prohibited. Persons responsible for schedule compliance must start reading installation guides and ensure an acceptable environment is created prior to floor covering installation and that service environment be maintained thereafter. Installation of any resilient floor covering product needs to occur under proper environmental control. This conditioning appears even more critical for many LVT/LVP products.
Second, there is need to recognize the temperature at a floor surface may be significantly higher than the ambient air temperature in any room with glass windows or walls. Some manufacturers of LVT/LVP specifically address this concern with statements such as:
A. “Use …epoxy adhesive in areas where the product will be subjected to direct sunlight…or temperature fluctuations.”
B. “Excessive temperature due to direct sunlight can result in thermal expansion”
To exemplify this concern, this agency set recording data loggers on a distressed floor adjoining a glass wall. The loggers recorded for a ten day period and reported daily high temperature exceeding 100°F at the floor surface. Yes, the floor covering had expanded and become distressed and it must be noted, the HVAC system was operational during the period monitored.
2. Dimensional instability inherent in a product or batch of product. When called about a distressed LVT/LVP floor system, it is this agency’s suggestion that virgin, uninstalled product be placed on a flat surface i.e. a conference table and allowed to acclimate for at least 72 hours. If a product will not naturally lay flat on a table top, it will not remain flat on a floor! Attempts to utilize “stronger adhesives” are typically to no avail. The product should be deemed defective and replaced.
Dimensional instability of LVP and LVP products may be attributed to a number of causes, including service environment as noted above. However, the specifier is wise to consider the number of component layers within the body of any product along with the volume and type of recycled content. Recycled material found in LVT/LVP products may be post-production, taken from the production floor or post-consumer, which may have unknown sourcing. Sourcing and content of post-consumer recycled materials is likely more closely regulated by domestic manufacturers than foreign manufacturers. This subject should be closely considered when specifying floor coverings.
3. Installation instructions, sub-floor and trowel requirements. Most U.S. manufacturers of resilient floor coverings reference ASTM F710 “Standard Practice for Preparing Concrete Floors to Receive Resilient Flooring” in data sheets or installation guides. ASTM F710 states “The surface of concrete ﬂoors shall be ﬂat to within the equivalent of 3⁄16in. (3.9mm) in 10ft, …
and within the equivalent of 1/32in. (0.8mm) in 12in.”. We find that most floor covering installation contractors do not own a copy of ASTM F 710 and rely of the text of a manufacturer’s installation guide. Further, while most floor covering installation contractors carry either a 6-foot straightedge or a 10-foot straightedge, I have not witnessed anyone check a large commercial floor surface with a 1-foot straightedge.
While a few manufacturer’s quote the ASTM F710 requirement, typical language in other manufacturer’s literature include simpler instruction allowing no more than a 3/16in gap (6/32in) under a 10-foot straightedge, or tighten the requirement to a 1/8in gap (4/32 in) under a 6-foot straightedge.
Adhesive trowel notch requirements for most troweled down adhesives used to install LVT/LVP products is 1/32in. notch depth. Consider the fact that trowels are not held at a 90° angle to the concrete, most trowels are held at a 60° angle, meaning that the height of an adhesive ridge left by this trowel is slightly less than 1/32in in height. In simple translation, very flat floors are required to ensure full coverage of adhesive on the back of floor coverings. If the LVT/LVP product is only slightly rigid, installation over a floor with only 1/32in. dips or “bird baths” may not permit the floor tile to fully contact the adhesive film. This deficiency may occur even when floors are rolled with the required steel roller. The net result is incomplete adhesive coverage and “hollows” when the floor is sound tested. The lack of complete bond only enhances any negative effect of floor surface temperature variations.
4. Plasticizer migration from floor covering materials. As described in ASTM F1700 and ASTM F1066 product sold as LVT/LVP contain plasticizers. This is true of virtually all plastics and allows products made plastic to be pliable. It must be noted that plasticizers are not chemically combine in plastic materials, but rather mechanically blended. They do leach out, over time and typically do not present a problem for the floor covering system or its installation. However, excessive plasticizer migration and adhesive degradation is reported on a growing number of LVT and LVP installations. The effect is typically destruction of adhesive bonds and a lingering odor of alcohol. We are not aware of any ASTM specifications or standards that deal with the suitability of a plasticizer for use in resilient floor coverings. Further, we are not aware of any standard quantifying allowable rate of natural plasticizer migration. Plasticizer migration claims can be the most contentious and typically require lab analysis in an effort to judge cause and effect.
Plasticizer migration is often attributed to moisture and alkali emission from concrete subfloors. Alkaline hydrolysis can be driven by moisture in or emanating from concrete. It can also be triggered by moisture from adhesives applied to concrete surfaces. A literature study published in 2007 by Sintef of Oslo reported:
“Water based dispersions (latexes) based on acrylate, vinyl acetate or ethylene vinyl acetate copolymers typically contain 25-30 % water by weight, meaning that 55-60 g of water will be added to the substrate as part of the adhesive per square meter. Water from the adhesive that cannot evaporate to the air will be absorbed into the concrete and cause the relative humidity of the concrete to increase. Experiments performed by Sjöberg … show that the relative humidity increases sharply at the concrete surface shortly after bonding the flooring material. The relative humidity in the top 3-5 mm of the concrete in (one experiment) rose well into the range that is considered to be critical for alkaline hydrolysis (85-95 % RH). In an unlucky case the relative humidity under a tight flooring material that prevents evaporation (e.g. PVC) may rise above the critical relative humidity for alkaline hydrolysis of a particular adhesive or floor covering.”
As noted above, plasticizer migration claims can be the most contentious. Is the problem due to poorly compounded plasticizer, poorly cured floor covering structure, excessive concrete moisture emission, or the impact of moisture contained in the floor covering adhesive?
5. Moisture and alkali emission from concrete subfloors. This final causation is not unique to LVT/LVP. Virtually all modern floor coverings and adhesives can be negatively impacted by excessive concrete moisture emission and the alkali it carries. This agency defines moisture transmission as that which occurs through slab-on-ground concrete resulting from the lack of an effective sub-slab vapor retarder. Moisture emission may be the result of transmission, or moisture emanating from concrete suspended on a metal deck or slab-on-ground placed directly over a high quality sub-slab vapor retarder. Regardless of source, control of moisture emission is paramount to the success of any adhered floor covering.
This author believes the market for LVT and LVP product will continue to expand. Design flexibility appears virtually endless and end-user acceptance of the product group is very high. The final intent of this paper is to encourage close scrutiny of manufacturer’s advertising claims, published performance test data, product attributes and installation requirements to ensure, to the extent possible, that the owner will receive both the visual aesthetic that was desired and the performance anticipated
Copyright 2017 GEORGE DONNELLY TESTING and INSPECTIONS