The Moisture Measurement Blog

LVT floors offer many great features: designs that mimic natural wood or stone, superior durability and easy maintenance. These qualities make LVT vinyl floors an ideal choice for both residential and industrial spaces, particularly those with high foot traffic. Above all, LVT is waterproof, making it the perfect choice for entryways, hallways, bathrooms or kitchens. But despite its resilience, moisture problems in LVT vinyl floors can still occur due to installation errors or environmental factors.

The Impact of Temperature and Moisture on LVT Floors

Temperature:
Even though LVT (Luxury Vinyl Tile) floors are synthetic, they still expand and contract in response to temperature changes. Installers must account for this by leaving expansion gaps. Otherwise, if the expansion gaps have not been properly installed, gaps between planks, buckling or cupping and edge curling can occur. 

Moisture:
Moisture Problems in LVT vinyl floors primarily arise when excessive moisture accumulates beneath the floor planks. That can lead to defects like bubbling, cupping, edge curling, warping and even mold growth. High moisture levels can come from various sources, including concrete slabs, lack of proper vapor barrier under the slab, or from poorly sealed exterior walls. Moisture can also seep in through gaps in the LVT floor, if the installation was not done correctly. Water from plumbing leaks and pipe brakes may also slowly migrate into the area below the LVT floor. High moisture levels in concrete substrates may require moisture testing, either in-situ probe tests or calcium chloride testing. Best advice as always, follow the floor manufacturer’s installation manual.

Mold and Condensation Risks:
High moisture levels beneath LVT floors increase the risk of mold growth, which can damage the subfloor and potentially affect the building’s framing components. Mold also poses health risks by contaminating the air. More info on mold.

Additionally, when high moisture levels are present under the floor planks, small temperature fluctuations can cause condensation. For example, during night-time, temperature drops, floor planks cool down leading to condensation on their underside. The trapped moisture provides an ideal environment for mold to grow. 

 

Why Moisture Problems in LVT Vinyl Floors Can be More Severe 

Moisture issues in LVT floors do not originate from the floor planks themselves. Instead, they mostly  result from moisture accumulation directly underneath the LVT floor planks.

Although LVT floors are waterproof and do not absorb water, they also inhibit the exchange of humidity between the areas above and below. This means, that moisture trapped beneath the floor cannot escape, creating an ideal breeding ground for mold. Moisture or high humidity above the floor is less of a concern because it can be easily ventilated. In contrast, moisture beneath the LVT remains trapped, which can eventually lead to significant problems, regardless of the moisture’s origin.

Case Study of LVT Floor Failure

The floor installation took place in 2021, and the customer notified the builder in the spring of 2024 that the floor had problems. An inspector was called to determine the cause for the floor failure.

In most cases, the first assumption is that the floor itself was defective. However, for this case a lab test of the LVT planks revealed no issues.

The inspector identified that the failure was due to improper installation and elevated moisture levels in the building, which led to edge curling and cupping. The installation mistake was that the floating floor was pinned or glued in places. This prevented the floor planks from expanding and contracting properly, leading to edge curling and cupping. In addition, while obtaining numerous moisture measurements, the inspector noticed, that the severity of the defects increased with higher moisture levels.

The inspector used the Ligno-VersaTec moisture meter to measure moisture levels underneath the LVT floor planks. In areas not affected by moisture, the moisture meter showed low numbers around 3.1. In contrast, moisture levels as high as 9.3 were recorded in areas with more severe curling. The higher the moisture readings, the more severe the defects. The settings for the Ligno-VersaTec were #10 and depth 1/4″.

Measuring Moisture of LVT Floors and Other Non-Wood Materials

Wood moisture meters indicate wood moisture as a percentage of the wood’s dry weight. When measuring materials like LVT, moisture meters are still useful, although the indicated value is qualitative and not quantitative. When measuring non-wood materials such as LVT, it is best to compare the measured values to a dry sample as base line.  Since vinyl itself does not absorb moisture, higher measurements indicate elevated moisture levels directly underneath the floor planks.

In case of the LVT floor: The base value for the Ligno-VersaTec was 3.1 on material setting #10 and 1/4″ depth. No edge curling or cupping was observed in areas with similar low values. However, for higher values, the moisture defects became more pronounced. 

Lignomat’s Moisture Meters

The Ligno-Scanner SDM, Ligno-DuoTec BW, and Ligno-VersaTec are the only pinless, dual-dpeth moisture meters from Lignomat with the settings #10 and depth 1/4″. The meters have proven to reliably detect different moisture levels underneath LVT vinyl floors. 

All moisture meters from Lignomat indicate wood moisture in percent. The SDM, BW and VersaTec have calibrations for different wood species, Drywall and Gypsum and reference scales for non-wood products. Three reference scales are available with different sensitivity levels.

#0 for wood composites and engineered products
#1 for building materials, panels other than concrete, LVT
#25 for concrete and cementitious materials

When using one of the meters to measure moisture underneath vinyl floor planks, we suggest using material setting #10 and 1/4″ depth. First, obtain measurements in unaffected areas to confirm that the base value of the floor to be tested is actually 3. Then, any moisture measurements higher than 4 indicate elevated moisture levels underneath the floor planks, allowing to detect potential moisture problems early or to inspect floor failures.

Summary

Moisture-related issues with luxury vinyl tile (LVT) primarily occur when excessive moisture accumulates beneath the flooring. Due to LVT’s low moisture permeability, any moisture trapped underneath the floor can become a serious problem – bubbling, warping, cupping and mold growth may occur. These problems are most often caused by improper installation or by a high moisture environment underneath the floor planks that was not addressed before laying the LVT. High moisture levels in concrete substrates may require moisture testing, either in-situ probe tests or calcium chloride testing. Best advice, follow the floor manufacturer’s installation manual. 

Temperature-related issues with LVT flooring occur when the material expands and contracts with temperature fluctuations. This can lead to gaps between the planks, cupping or buckling, if the floor is not installed properly and exposed to temperature changes. Common causes include direct sunlight, excessively high underfloor heating, or heating turned off during cold winter months. To prevent these issues, it is essential to leave expansion gaps, which allow the floor planks to expand, but also to avoid excessively low or high temperatures.

From a LVT Manufacturer:

“LVT is an exceptional durable floor covering, and properly installed and cared-for new flooring will be easy to maintain and will look great for years to come. Failure to follow the installation instructions may result in damage to the floor and void the floor’s warranty.”