Flooring Forensics: Understanding acclimation to avoid related flooring failures – May 2024

By Walter Bell

The need to acclimate the various components of flooring systems-including floorcoverings, adhesives, accessories, coatings and other materials-cannot be understated. And it’s not just the materials, but also the building that requires acclimation. Many flooring failures occur due to not understanding the acclimation process and not following manufacturer guidelines and industry standards related to acclimation.

THE IMPORTANCE OF ACCLIMATION
Improper acclimation can lead to floors bowing, cracking, gapping and peaking, as well as interlocking mechanisms breaking and other unacceptable conditions that result in a flooring failure and voiding of flooring system warranties.

In a recent inspection of a new school for its board of education, my investigations onsite and interviews with various parties that had knowledge of the jobsite conditions and flooring installation determined that the building was not fully weathertight, and the permanent HVAC system was not yet operational before the flooring was installed. Temporary measures were not adequate. In addition, the flooring products were not properly acclimated. The result was that all the flooring in the large school failed due to unacceptable gapping. The only exceptions were the ceramic tiles in the kitchen and restrooms.

After reviewing the report and meeting with school system leadership, the general contractor agreed to replace all the flooring (with the above-noted ceramic exceptions). Investigations revealed that pressure had been placed on the flooring contractor to install the flooring prior to the jobsite ambient environmental conditions and flooring products meeting acclimation requirements as set forth in the legally binding construction documents, which included architectural specifications, manufacturer guidelines and industry standards.

It was a very costly mistake by the flooring contractor to give in to pressure to install the flooring outside of the manufacturer’s guidelines and accepted industry standards. Decisions by flooring contractors to install a floor that does not conform to specified guidelines and standards greatly increase their liability. Often, courts place the liability on the flooring contractor as the professional and not the general contractor or owner, who may have instructed the flooring contractor to proceed with the installation.

ACHIEVING ACCLIMATION
What does it mean to acclimate flooring materials? Acclimation is the process of conditioning the flooring materials to reach a temperature and humidity equilibrium in line with that of the building’s ambient environment expected during its normal service conditions. “Normal service conditions” are those expected during the routine operation of the building once it is fully enclosed with permanent doors and windows, and the permanent HVAC system is fully operational.

Temporary enclosures and temporary heating and cooling systems can result in the ambient environment not mimicking the environment once the permanent enclosures are in place and HVAC systems are operational. While these temporary systems may be adequate for certain trade work and worker comfort, they might not create an environment equivalent to when the building is occupied.

Prior to the delivery of any flooring materials, the building needs to be weathertight, with HVAC systems stabilizing the ambient environment at levels expected during normal building usage. Flooring product manufacturers will often have requirements for building acclimation prior to product delivery and installation.

The moisture content of wood subfloors and materials can also be affected by leaky temporary enclosures, as well as temporary conditioning systems that dry out the ambient environment of the building much lower than expected service conditions, or propane heaters that produce water vapor at a rate of about four cubic feet for each cubic foot of gas.

Substrate evaluation and preparation should not begin until a stable, conditioned environment has been established. For instance, Forbo Flooring Systems’ general installation guidelines for Marmoleum state, “Areas to receive material should be clean, fully enclosed and weathertight. The permanent HVAC should be fully operational and controlled and set at a minimum temperature of 65° F (18.3° C). If this is not possible, the areas should be acclimated and controlled by means of temporary HVAC to the service level conditions expected during occupancy. The temperature and humidity should range from 75° F ± 10°F (23.9° C ± 5.5° C) with a 50% ± 10% ambient relative humidity. These conditions MUST be established at least seven days prior to beginning the installation, maintained during the installation and continued for at least seven days following the installation.”

Site conditions can dramatically affect the performance of the adhesive. Temperature, ambient relative humidity, substrate porosity and air circulation will determine the open, working and curing time of the adhesive. Not respecting these limits can result in an installation failure. Mirage’s installation guides for classic and engineered prefinished hardwood floors both state, “Wooden subfloor moisture must read between 6% and 10% and differential between boards and subfloor must be less than 4%…. If moisture reading is too high, postpone installation, find moisture source, and correct it if needed. Raise heat and increase ventilation until proper conditions are met.

“Keep boxes of wood in room where flooring is to be installed for at least 24 hours before installation.

“Owner and installer are solely and jointly responsible for pre-installation subfloor moisture level check and must ensure that all conditions and/or specifications listed in this guide have been thoroughly met prior to installation of hardwood floor.”

Natural flooring products such as hardwoods, cork, linoleum, bamboo and coconut palm are hydroscopic building materials. That means that these flooring products have micropores that will absorb and release water vapor with differentials in the surrounding water vapor levels (relative humidity). The ability of different materials to absorb and release water vapor will vary, causing an impact on the time needed for the material to acclimate.

The term “permeable flooring” is used to describe a porous material that allows a liquid (for example, water) or gas (for example, water vapor) to pass through the pores (capillaries) of the material. Not all porous materials are permeable if the capillaries do not interconnect.

The National Wood Flooring Association’s Technical Publication A100 Moisture and Wood states, “Bringing wood flooring to equilibrium includes conditioning the materials in a stable environment as long as necessary to ensure the materials have reached the proper moisture content based on the temperature and humidity levels of the facility. However, once the environmental conditions change above and/or below the floor, so will the moisture content of the flooring.”

Temperature also influences the acclimation process of flooring materials. Increased temperatures can make materials expand/swell, and lowered temperatures can make materials contract/shrink. Although many nonporous materials-such as most vinyl flooring-may have a very low permeability, they may be subject to expansion and contraction from changes in temperature. The dimensional stability of various flooring types can very drastically change the acclimation process requirements.

Another factor in acclimation is the difference in temperature and moisture content of the materials to that of the conditioned building. Larger differentials may require longer acclimation time. Different seasons, along with different geographic regions, can also affect the ambient environment.

ACCLIMATION TIME
With so many different factors affecting the acclimation process of flooring materials, there are no set timetables for a product to acclimate. Most flooring manufacturers have established a minimum time needed for a product to acclimate, but this might be for typical conditions that may or may not exist on a particular jobsite. Another potential caveat is the conditions of the material prior to arriving on the jobsite. Prior to materials being delivered to a jobsite, the products should be kept within the environmental ranges specified in the manufacturer’s technical data sheet.

Manufacturers may have additional requirements for the acclimation process regarding stacking of the flooring and whether to open boxes or packaging during the acclimation process. Flooring contractors should have moisture meters, thermos-hydrometers and dataloggers to measure and log the conditions of the building environment, substrates and flooring materials as part of their quality assurance and quality control (QA/QC) programs. As technical consultants, we record these conditions when commissioned to provide QA/QC for flooring installations.

The Carpet and Rug Institute’s Installation Standard CRI 104 for Commercial Carpet states, “It is recommended that carpet and installation materials be allowed to acclimate in the installation area for a minimum of 24 hours at a temperature of 65-95ºF (18-35ºC). Carpet must be adequately protected from soil, dust, moisture and other contaminants. Follow manufacturer’s instructions for acclimation.”

Mannington Commercial’s installation guidelines for luxury vinyl plank and tile note, “Mannington Commercial LVT flooring, adhesive, jobsite and subfloor must be acclimated to a stable condition before installation. Before starting the Mannington Commercial LVT installation, ensure the following are satisfactorily completed:

“Acclimation: The installation and materials to be installed shall be maintained at a minimum of 65°F (18.3°C) and a maximum of 85°F (29.4°C) for 48 hours before, during and for 48 hours after completion of the installation, and continue to maintain the flooring at a temperature between 55°F-85°F during its service life.

“Relative humidity level extremes should also be avoided. General recommended humidity control level is between 35%-55%. If a system other than the permanent HVAC source is utilized, it must provide proper control of both temperature and humidity to recommended or specific levels for the appropriate time duration.”

Copyright 2024 Floor Focus

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