Flooring Forensics: Quality assurance/control activities prevent flooring failures – October 2024
By Walter Bell
My investigations into flooring failures often reveal a lack of quality assurance (QA) and quality control (QC) activities that should have occurred as part of the floorcovering installation or coating application process. With adequate QA/QC processes, many of these failures could have been avoided.
UNDERSTANDING “QUALITY”
While many flooring contractors and installers know about floorcovering and coating systems and the term “quality,” fewer understand quality management systems (QMS) and how they apply to the flooring industry. QMS include industry standards, quality management plans, QA practices and QC measures.
Quality in Construction: The Construction Specifications Institute Project Delivery Practice Guide states that quality “refers to the project requirements established in the contract documents.” The American Society for Quality (ASQ) defines quality as “1) the characteristics of a product or service that bear on its ability to satisfy stated or implied needs; 2) a product or service free of deficiencies.”
The Project Management Institute (PMI) Guide to the Project Management Body of Knowledge PMBOK Guide and Standard for Project Management (ANSI/PMI 99-001-2021) states that “project quality entails satisfying stakeholders’ expectations and fulfilling project and product requirements. Quality focuses on meeting acceptance criteria for deliverables. Project quality entails ensuring project processes are appropriate and as effective as possible.” The PMI’s PMBOK goes on to say, in “building quality into processes and deliverables, maintain a focus on quality that produces deliverables that meet project objectives and align to the needs, uses and acceptance requirements set forth by relevant stakeholders.”
Quality Management and Quality Management System: ASQ defines quality management as “managing activities and resources of an organization to achieve objectives and prevent nonconformances” and QMS as “a formal system that documents the structure, processes, roles, responsibilities and procedures required to achieve effective quality management.”
Quality Assurance and Quality Control: The Construction Specifications Institute Project Delivery Practice Guide states that quality assurance “refers to the procedures for guarding against defects and deficiencies before and during the execution of work.” This guide states that QC “refers to the procedures for evaluating completed activities and elements of the design for conformance with the requirements.”
The guide goes on to state that “quality assurance and quality control are not exclusive of each other.” QA and QC processes can run concurrently.
IMPLEMENTING QUALITY
A quality plan needs to be established to get a quality system implemented. The American Society for Quality defines a quality plan as “documented information that provides the activities or methods to be taken to achieve objectives and meet specified requirements.”
With the goal to meet specified requirements, the process starts with the review of the contract specifications. With commercial projects, there will almost always be a set of architectural specifications, often referred to as the “project or construction specs,” that outline contract binding requirements for the performance of the project. Among other things, the project specs will typically outline the products to be used, standards to be followed, and QC and QA processes required.
When the specs require following manufacturer installation instructions, industry standards or other documents, those referenced documents become a part of the project contract documents. Through the contract requirements, voluntary compliance standards, such as “ASTM F710 Standard Practice for Preparing Concrete Floors to Receive Resilient Flooring,” become mandatory compliance documents for that project.
This linking of requirements also applies to required testing and other processes. Certain testing, such as concrete moisture testing, may be part of the architectural specifications, but if not, it is mandatory if the specified product installation guidelines require it. This makes it important to not stop with a review of the construction project specifications (first tier) but all referenced documents (second tier) and any requirements from the second tier to follow other testing procedures or guidelines (third tier).
QUALITY ASSURANCE AND CONTROL TESTING
Performing testing processes can potentially reveal issues that could cause flooring failures. In our forensic floor failure analysis projects, we use these test methods and practices as part of our investigations into the root cause analysis of failures.
Ambient Environmental Conditions: Most flooring products have requirements for the ambient environmental conditions of temperature and relative humidity to be within a specified range. Although this is a simple testing procedure using a thermo-hydrometer, it is very often not performed. We recommend installing datalogging systems to record the temperature and relative humidity prior to the acclimation of the flooring and left until the project is turned over to the owner.
With many failures, this kind of data becomes an important part of an investigation. It can show that the flooring contractor or installer met the requirements, or that when they were not onsite, the HVAC system was turned off or not functioning properly and caused dimensional changes in the flooring that was not the fault of the flooring contractor or installer.
Concrete Moisture and Surface pH: Most flooring contractors are familiar with requirements that include testing of concrete moisture (ASTM F1896 and F2170) and concrete slab surface pH (ASTM 3441). The “ASTM F3441 Standard Guide for Measurement of pH Involving Resilient Flooring Installations” was published in 2023, but many still reference the old pH testing procedure in ASTM F710. High pH levels can have detrimental effects on adhesives and other components.
Concrete Slab Porosity: The “ASTM F3191 Standard Practice for Field Determination of Substrate Water Absorption (Porosity) for Substrates to Receive Resilient Flooring” was published in 2016 but is still not performed as widely as it should be. Porosity is important for most flooring adhesives, primers, self-leveling underlayments, patching and coatings to obtain a sufficient mechanical bond to a cementitious substrate.
Mat Bond of Resilient Flooring: The “ASTM F3311 Standard Practice for Mat Bond Evaluation of Performance and Compatibility for Resilient Flooring System Components Prior to Installation” was published in 2019, but mat bond evaluations were performed for many years prior. This practice is recommended for the installation of a resilient flooring system to a concrete slab or when using products from different manufacturers.
Although the following QA and QC testing and evaluation processes are less commonly performed, it does not make them less needed for the prevention of potential flooring system failures.
Substrate Compressive Strength: A manufacturer’s technical data sheet or installation guidelines may require a concrete slab be of a minimum compressive strength. Although the documents may not directly require testing, it is needed to determine if those requirements are being met.
In this example, we often use a concrete rebound hammer to perform a nondestructive evaluation of the concrete using the “ASTM C805 Standard Test Method for Rebound Number of Hardened Concrete” to get an estimate as to hardness. This test provides data to assess the uniformity of the concrete slab and to delineate variations in hardness.
Tensile Strength of Concrete Slabs and Tensile Bond of Underlayment and Patching Materials: Some manufacturers require a minimum tensile strength of a concrete substrate for the installation of underlayment and patching materials, or for the application of floor coating systems.
When required, we test in accordance with “ASTM C1583 Standard Test Method for Tensile Strength of Concrete Surfaces and the Bond Strength or Tensile Strength of Concrete Repair and Overlay Materials by Direct Tension (Pull-off Method)” using a highly accurate electronically controlled hydraulic pull testing device. The ASTM D7234 test method described below can be adapted to determine the surface strength of an uncoated concrete slab. Depending on the target testing depth, C1583 or D7234, or both, may be performed on the concrete slab.
This quality process is extremely beneficial for testing the bond strength of cementitious underlayments and patching materials, especially where a flooring system will have heavy rolling loads, such as in a hospital environment or other demanding commercial and industrial applications that place higher stress on the components of a flooring system.
Tensile Bond Strength of Concrete Floor Coatings: Coating manufacturers or usage specifications may require a minimum tensile bond strength to meet performance criteria or other requirements for a coating system. For this, we test in accordance with “ASTM D7234 Standard Test Method for Pull-Off Strength of Coatings on Concrete Using Portable Pull-Off Adhesion Testers.”
This testing can validate that the subfloor has a proper surface profile and cleanliness to achieve sufficient bond strength for the system requirements. As with the coating component of a concrete moisture mitigation system, that system will become a permanent and integral part of the subfloor system, in part if the system achieves proper bond strength.
It can also reveal that a coating has not achieved proper curing and bond strength, which could be caused by potential incompatibility issues of a coating with the substrate or improper mixing of the coating material.
Floor Coating Dry Film Thickness: The coating manufacturer technical data sheets for concrete moisture mitigation system coatings and for many other high-performance floor coatings typically require the dry film thickness (DFT) to be within a specified range to perform as intended.
The thickness of a concrete moisture mitigation system is directly related to the permeability rating of the system, so meeting the minimum requirements is critical for the system to perform as intended. Other factors affected by DFT include adhesion, chemical resistance, durability, flexibility and wearability.
For this determination, we test in accordance with “ASTM D6132 Standard Test Method for Nondestructive Measurement of Dry Film Thickness of Applied Organic Coatings Using an Ultrasonic Coating Thickness Gage.”
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