When it comes to laminate flooring installation, subfloor moisture testing is an important step that you should never overlook.
Failing to assess moisture levels in the subfloor can lead to numerous problems. This minimizes the integrity and longevity of your laminate flooring.
In this guide, we will explore:
- the importance of moisture testing,
- the impact of excessive moisture on subfloors and laminate flooring,
- various moisture testing methods,
- interpret moisture test results
- practical tips for addressing moisture issues.
By following these guidelines, you will ensure a successful and long-lasting installation for the different types of laminate flooring.
How does moisture on subfloors affect laminate flooring?
Excessive moisture in subfloors can have detrimental effects on the structural integrity of your flooring.
In particular laminate flooring contains wood materials in its layers, which are highly susceptible to water damage.
In case there is moisture in your subfloor, it starts seeping through the laminate base layer. Over time it will contribute to contracting and expansion.
When exposed for long, you will note some of the problems discussed below:
Recommended: Best floors for wet areas.
main problems caused to laminate floors by high-moisture levels in subfloor
Buckling:
Excessive moisture can cause the laminate boards to expand and buckle, resulting in uneven surfaces and raised areas.
This can make the floor unstable and potentially cause tripping hazards.
Warping:
Moisture can penetrate the laminate material, causing it to warp, twist, or peel over time.
This constant movement results to swelling of the laminate base layers, which in turn transfers to the laminate flooring above.
The lifting not only results in a distorted appearance, – with boards curving or lifting at the edges- but also the laminate planks start separating.
It is for this reason why we recommend that you don’t install laminate directly on concrete. Using underlayment and moisture barriers is the best protective method.
Mold and mildew growth:
Moisture creates a favorable environment for mold and mildew to thrive.
As a result, if your subfloor is moisture-laden, it creates an ideal breeding ground for the mold and mildew.
If not addressed timely, the mold and mildew rapidly spreads throughout the subfloor and affects the entire laminate base layer.
If the subfloor remains damp for an extended period, mold and mildew can develop between the subfloor and laminate flooring.
This results to unpleasant odors and potential health issues.
In places like basements, constant presence of moisture creates perfect conditions for the mold and mildew growth.
Not only does this pose a health risk, but also leads to discoloration, odor, and degradation of your laminate flooring.
Staining or discoloration:
Water or moisture can seep through the joints or gaps between the laminate boards and the subfloor. It then causes staining or discoloration of the laminate material.
This can leave unsightly marks on the surface.
In most cases, this staining happens in wet-prone areas like kitchens and laundry areas. These are areas where liquid spills and you will likely fail to clean up promptly.
When such spills seep into the laminate flooring, it causes permanent staining.
It is for this reason that we recommend the installation of waterproof laminate for high-moisture areas.
Deterioration of the laminate material:
Continuous exposure to high moisture levels can cause the laminate material to break down, start peeling, and deteriorate over time.
This can lead to the laminate losing its structural integrity, becoming soft, or developing surface cracks.
Delamination:
Excessive moisture can cause the layers of the laminate flooring to separate, resulting in a process called delamination.
This can lead to a weakened floor surface and a loss of adhesion between the layers.
Odor:
Moisture trapped underneath the laminate floor can generate a musty odor, particularly if mold or mildew is present.
This can create an unpleasant indoor environment.
Importance of Subfloor moisture testing
Proper moisture testing is important.
It ensures that you have acceptable moisture levels in your subfloors before installation of the laminate flooring.
Failure to conduct the test increases the possibility of having your laminate floor developing such problems as: buckling, warping, mold growth, bad odor, delamination, wear and tear, and discoloration.
Moisture testing thus allows you to critically assess the moisture conditions of your subfloor before proceeding with the laminate flooring installation.
By understanding the level of moisture in your subfloor or lack thereof, you can effectively prevent potential issues and ensure long-term durability of your laminate flooring.
The following are the 4 key reasons why moisture testing is important:
1.Determining High Moisture Areas
Moisture testing helps you to identify areas of the subfloor with elevated moisture levels.
This is particularly important in areas prone to moisture, such as basements, bathrooms, or areas near exterior walls.
By pinpointing high moisture areas, you can take appropriate measures to mitigate moisture-related problems before they impact your laminate flooring.
For instance, if moisture testing reveals high moisture content in a basement subfloor, you may decide to install a moisture barrier or opt for a different type of flooring that is more suitable for that specific environment.
2.Preventing Floor Damage:
Excess moisture can cause serious damage to both the subfloor and laminate flooring.
Moisture testing helps detect potential risks and allows you to take preventive measures.
By addressing moisture issues before installation, you can avoid problems such as warping, buckling, or mold growth, ensuring the longevity and appearance of your laminate flooring.
Imagine a scenario where moisture testing reveals high moisture levels in a concrete subfloor due to inadequate waterproofing.
By addressing this issue before installing the laminate flooring, you can:
- (i)Re-do the concrete subfloor to improve waterproofing
- (ii)Apply appropriate moisture barriers and sealants to prevent moisture infiltration and potential damage to the flooring.
- (iii)Decide on a flooring alternative that can withstand high moisture content.
3.Determining Moisture Mitigation Strategies:
Moisture testing provides valuable information for developing appropriate moisture mitigation strategies.
Based on the moisture test results, you can determine the necessary steps to address moisture issues and create a suitable environment for laminate flooring installation.
For example, if the moisture testing indicates high moisture levels in a plywood subfloor, you might decide to implement measures such as:
- improving ventilation,
- using moisture barriers,
- or applying moisture-resistant sealants to mitigate the moisture problem effectively.
4. Adhering to Manufacturer’s Guidelines:
Most laminate flooring manufacturers provide specific moisture requirements and guidelines for their products.
Failure to follow these guidelines may result in voided warranties and compromised performance.
Moisture testing helps ensure that the subfloor moisture levels align with the manufacturer’s recommendations, allowing for a successful installation and maintaining the warranty coverage.
For instance, if the manufacturer specifies a maximum moisture content of 4% for the subfloor, conducting moisture testing becomes crucial to ensure compliance.
By adhering to these guidelines, you can protect your investment and have peace of mind knowing that you’ve followed the manufacturer’s instructions.
Remember that the flooring warranty determination may also include a follow-up of whether you carried a subfloor moisture test.
If the manufacturers note that your laminate flooring damage was due to high moisture content-as a result of not testing- your warranty will be voided.
Methods of Moisture Testing on Subfloors.
We have a number of moisture tests with each offering unique insights about the level of moisture present. Understanding these methods will help you to choose the most suitable approach for your specific project:
1.Calcium Chloride Moisture Testing (ASTM F1869)
The Calcium Chloride Moisture Testing method also known as the ASTM F1869 test, measures the moisture vapor emission rate (MVER) of the subfloor.
The ASTM F1869 test is widely recognized in the industry and provides quantitative data about the moisture content of the subfloor.
It is commonly used for concrete subfloors and helps assess their suitability for laminate flooring installation
It involves placing a sealed calcium chloride test kit on the subfloor surface for a specified period, typically 24 to 72 hours.
The calcium chloride absorbs moisture from the subfloor, and the weight gain is used to calculate the MVER in pounds per 1,000 square feet per 24 hours.
For instance, I recently conducted a calcium chloride test on a concrete subfloor which yielded an MVER result of 5 pounds per 1,000 square feet per 24 hours.
This result indicated that the subfloor has a moderate moisture vapor emission rate.
Read our step-by-step guide on how to conduct the calcium chloride moisture test.
2.Relative Humidity (RH) Testing
The relative humidity (RH) testing involves using specialized probes to measure the moisture content within the subfloor.
RH testing is a widely recognized and accurate method for assessing the moisture conditions within the subfloor.
It provides valuable information for understanding the moisture dynamics and potential risks for laminate flooring.
This method provides information about the relative humidity level in the subfloor, which is critical for determining whether the conditions are suitable for laminate flooring installation.
RH testing typically involves drilling a small hole in the subfloor and inserting a probe to measure the moisture content at a specific depth.
According to industry standards, a relative humidity level below 75% is generally considered acceptable for laminate flooring installation.
In this case, if you conducted an RH test on a concrete subfloor which reveals a relative humidity level of 65% at a depth of 40%, then you would know that the moisture level is acceptable for installation of your laminate floor.
For comprehensive information, please see our step-by-step guide on how to conduct RH testing.
3. Moisture Meter Testing
Moisture meter testing is a convenient and non-invasive method that provides instant moisture readings.
Manufacturers recommend that you should undertake the test in about 20 locations per 1000 square feet of flooring, then average to get a comprehensive overview of the moisture content range.
The moisture meter testing is a practical and efficient method that can be used on various subfloor types.
It offers quick results and is useful for spot-checking moisture levels during the installation process.
This method involves using a handheld moisture meter to measure the moisture content of the subfloor by pressing the meter against the surface or inserting the pins into the subfloor material.
Moisture meters provide immediate moisture readings, allowing for quick assessments of the subfloor conditions.
Read our comprehensive guide on moisture meter-testing.
Interpreting Moisture Test Results
After conducting moisture tests on the subfloor, it is important that you accurately interpret the results to make informed decisions about the installation of laminate flooring.
Moisture test results are typically presented as a percentage, representing the amount of moisture present in the subfloor.
By comparing these results to industry standards and manufacturer guidelines, you can determine whether the moisture levels fall within acceptable limits.
Let’s explore how to interpret moisture test results effectively:
1.Industry Standards & Guidelines
You should evaluate the moisture test results against industry standards and guidelines specific to the type of subfloor and the region’s climate.
These standards provide recommended moisture levels for successful laminate flooring installations. For example:
Wood Laminate Subfloor Moisture Standards
The National Wood Flooring Association (NWFA) suggests that wood subfloors should have a moisture content of 7 to 9 % or less before installing laminate flooring.
The NWFA further recommends that the maximum moisture content should be 12%, and above this, the subfloor would be too wet to support laminate flooring installation. In such cases, more drying is required for the subfloor.
The following are some of the moisture content levels on wood subfloors recommended by popular laminate flooring manufacturers:
| Flooring Manufacturer | Maximum Allowable Moisture Content in Subfloor |
| Mohawk | 12% |
| Quickstep | 12% |
| Kronotex laminate | 14% |
| Unilin | 12% |
| Mannington | 12% |
| Columbia | 12% |
| Toylys | 10% |
| Swiss Krono | 12% |
Concrete Subfloor Moisture Standards
The Concrete Moisture Testing Industry Group (CMTIG) recommends that concrete subfloors have a moisture vapor emission rate (MVER) of 3 pounds or less per 1,000 square feet per 24 hours for laminate flooring installation.
The companies that have the vapor standard of emission rate (MVER) standard of 3 pounds or less per 1,000 square feet per 24 hours for concrete subfloors include:
- Pergo
- Kronotex
- BerryAlloc
- Mohawk
- Columbia
- Quickstep
- Unilin
- Mannington
- Shaw
- Tarkett
- Armstrong Flooring
- Swiss Krono
2.Comparative Analysis:
Interpreting moisture test results also involves comparing the moisture levels of different areas within the subfloor or comparing the current test results with previous or baseline measurements.
This analysis helps identify potential moisture sources, areas of concern, or changes in moisture conditions over time.
For instance, I recently installed laminate flooring over plywood subfloor where comparative analysis came in handy.
The moisture tests we conducted in various areas of a plywood subfloor consistently showed moisture content levels ranging from 8% to 10%.
However, in one particular area, the moisture content measured over 15% consistently.
This significant difference suggested a localized moisture issue, such as a plumbing leak or inadequate waterproofing, which needed to be addressed before installing laminate flooring.
We actually found that one of the waste pipe near the walls where the edge of the plywood reached, was leaking.
Our plumber fixed the problem before we installed the laminate floor.
Had we ignored the problem or failed to conduct a moisture test, we would soon have to deal with water problems in our laminate floor.
Addressing moisture issues.
When moisture test results reveal elevated moisture levels in the subfloor, you need to address the issue before proceeding with the installation of laminate flooring.
Proper moisture mitigation and subfloor preparation are required for creating a stable and moisture-resistant foundation.
The specific approach to addressing moisture issues will depend on the severity of the problem and the type of subfloor. Let’s explore some common methods for addressing moisture issues:
Resolving the Source of Moisture:
Addressing the source of moisture is the easiest and most important method of addressing moisture issues in your subfloor.
If the moisture issue is caused by a plumbing leak, inadequate ventilation, or improper drainage, it is essential to resolve these underlying issues before proceeding with the installation of laminate flooring.
Repairing leaks, improving ventilation, or implementing appropriate drainage systems can help prevent future moisture problems.
For example, in a bathroom with inadequate ventilation, installing an exhaust fan or improving the existing ventilation system can help reduce moisture buildup and minimize the risk of moisture-related damage to the laminate flooring.
Moisture Barriers;
Moisture barriers, such as polyethylene sheets or specialized moisture-resistant membranes, can be installed over the subfloor to create a barrier between the subfloor and the laminate flooring.
These barriers help prevent moisture vapor from reaching the laminate and provide an additional layer of protection against potential moisture-related problems.
In areas prone to moisture, such as bathrooms or kitchens, using a moisture-resistant underlayment made of rubber or cork can help mitigate moisture issues and safeguard the laminate flooring from moisture-related damage.
You can either use polyethylene sheets or moisture-resistant membranes depending on your moisture level. To understand more, please read our comprehensive guide on moisture barriers.
Moisture-Resistant Laminate Products:
Opting for moisture-resistant laminate flooring products specifically designed to withstand higher moisture levels is another solution for addressing moisture issues.
These laminate products have enhanced moisture resistance properties, including water-resistant cores and moisture-resistant surface finishes, making them more resilient to moisture-related damage.
For example, in a coastal region with high humidity levels, choosing laminate flooring with water-resistant features, such as an HDF (high-density fiberboard) core treated with moisture-resistant additives and a waterproof surface coating, can provide better protection against moisture-related issues.
Conclusion
In summary, proper subfloor preparation is the key to a successful installation and the prevention of potential problems in the future.
Moisture testing allows you to assess the moisture levels in the subfloor and make informed decisions about the installation process.
It helps you identify any excessive moisture that could lead to damage and take necessary measures to mitigate it.
By addressing moisture issues proactively, you can avoid problems such as warping, buckling, or mold growth in your laminate flooring.
The methods of moisture testing, such as calcium chloride testing, relative humidity testing, and moisture meter testing, offer valuable insights into the moisture content of the subfloor.
Each method has its advantages and may be more suitable for specific situations.
Understanding the different testing methods allows you to choose the most appropriate one for your project.
Interpreting moisture test results is crucial in determining whether the moisture levels are within acceptable limits.
Comparing the results to industry standards and manufacturer guidelines helps you make informed decisions about the installation process.
It ensures that you proceed with the installation when the subfloor is adequately prepared or take necessary measures to address any moisture issues before proceeding.
Addressing moisture issues is essential to create a stable and moisture-resistant foundation for your laminate flooring.
Depending on the severity of the moisture problem, various remediation methods may be required.
These can include installing moisture barriers, using moisture-resistant underlayment, or opting for moisture-resistant laminate products.
By ensuring that the subfloor is dry, level, and free from any moisture-related issues, you set the stage for a successful and long-lasting laminate flooring installation.
Frequently Asked Questions:
Is a moisture barrier necessary for laminate flooring installation on a plywood subfloor?
The answer is: Yes, using a moisture barrier is still recommended when installing laminate flooring on a plywood subfloor.
While plywood is generally less prone to moisture issues compared to concrete, it can still absorb moisture if exposed to excessive humidity or water leaks.
A moisture barrier provides an extra layer of protection and ensures the long-term performance of your laminate flooring.
Can I install laminate flooring directly on a concrete subfloor without a moisture barrier?
It is highly recommended to use a moisture barrier when installing laminate flooring on a concrete subfloor.
Concrete is porous and can retain moisture, which can seep into the laminate flooring and cause damage.
A moisture barrier acts as a safeguard, preventing moisture vapor from reaching the flooring material and reducing the risk of issues like warping or mold growth.
Can I use plastic sheeting as a moisture barrier for laminate flooring?
While plastic sheeting may offer some temporary protection against moisture, it is not the ideal choice for a long-lasting moisture barrier.
Plastic sheeting is not specifically designed for this purpose and may not provide adequate moisture resistance.
It is best to use moisture barriers specifically manufactured for laminate flooring installations, such as polyethylene sheets or moisture-resistant membranes.
Can I install a moisture barrier over an existing laminate floor?
The answer is no: Installing a moisture barrier over an existing laminate floor is generally not recommended.
Moisture barriers are most effective when installed directly over the subfloor, creating a moisture-resistant layer between the subfloor and the new laminate flooring.
Installing a moisture barrier over an existing laminate floor may interfere with the flooring’s stability and may not provide the desired moisture protection.
Is moisture testing necessary if I plan to use a moisture barrier?
The answer is: Yes, moisture testing is still crucial even if you intend to use a moisture barrier.
Moisture barriers are designed to prevent moisture vapor transmission, but they do not address underlying moisture issues.
Conducting moisture testing helps identify any excess moisture in the subfloor and allows you to address those issues before installing the moisture barrier and laminate flooring.
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