Addressing Water-Damaged Floors

In response to the massive devastation of Hurricane Harvey, the growing threat of Hurricane Irma, and the peak of hurricane season, people across the country are coming together to aid in recovery efforts. Effects of flooding from the storms will continue for weeks and even months to come.

Although looking at a waterlogged home can seem overwhelming, not all flooding damage is irreversible. When it comes to water damage and wood floors, the NWFA has a quick guide for assessing the issue to avoid further damage.

It is important to understand that water will migrate to areas below the wood floor system anytime there is a flood. When water damage occurs, the wood flooring and subflooring systems must be evaluated to determine the extent of damage and ensuing repairs.

Subfloor Materials Evaluation

  • Plywood: swelling, distortion, and delamination can occur when exposed to high moisture levels. Moisture tests should be conducted using insulated pin, hammer-probe type meters on the surface, backing, and core, and in several areas of the damaged material to properly assess moisture.
  • Oriented Strand Board (OSB): swelling can occur with OSB when exposed to water. Swelling in OSB can create a decrease in density and a reduction in board strength.
  • Concrete: concrete is a porous material. It typically does not become damaged when exposed to water; however, adhesives, sealers and other compounds will slow the drying of a wetted concrete slab.
  • Drying: Dehumidifiers, heat, or regular airflow can accelerate the drying process. However, the subfloor should be within the flooring and adhesive manufacturer’s required moisture levels before flooring can be installed.

Wood Flooring Materials Evaluation & Remediation

  1. Identify the type of flooring and installation methods.
    1. Identify type of substrate.
    2. Existing materials below the flooring surface may create additional mitigation costs and concerns (i.e., asbestos underlayment, radiant heating systems, etc.).
  2. Determine the target moisture content for the geographic area and for the facility.
    1. Reference the Equilibrium Moisture Content Chart (EMC) chart.
    2. Consider the time of year repairs are to take place and assess the HVAC systems’ ability to sustain an adequate environment.
  3. Conduct moisture testing.
    1. Use insulated pin, hammer-probe type meters to achieve readings at multiple depths of flooring and subflooring material.
    2. Use pinless, dielectric meters to scan the flooring surface and map the damage.
    3. Check existing, unaffected wood for reference.
    4. Target should be within 2% of expected “in-use” moisture content.
  4. Use dehumidification systems to stabilize the ambient conditions and bring them within the target range.
    1. Some of the most effective types of dehumidification systems include desiccant systems and low-grain refrigerant systems.
    2. Dehumidifiers should be placed on the flooring surface as well as below the flooring surface (when applicable).
    3. Unconditioned areas directly below the wood subflooring system or sleepers, such as basements and crawlspaces, should also be opened to introduce heat and airflow. Any insulation on the underside of the floor joists should be removed.
    4. Many times, damage will dissipate or even completely disappear as the flooring dries out over time.
    5. Airflow and heat can be used to speed the natural drying process.
    6. Vacuum extraction systems include placement of large mats/panels that are attached to vacuum/suction systems designed to pull water from the flooring surface.
    7. Negative and positive air pressure systems force airflow beneath and within the flooring systems in order to decrease the moisture content by direct use of airflow.
    8. A buckled wood floor requires replacement wherever the buckling has occurred. Once the flooring has buckled, the fasteners or adhesives are no longer effective, and the system will never return to its original state. Once the moisture source has been identified and eliminated, the buckled portion of the flooring may be replaced. The remainder of the flooring should be treated as noted.

NWFA’s Brett Miller will be speaking on the issue at the CCA Global Insurance 2.0 Conference in St. Louis, MO this weekend. Miller explains,

“I’ll be working with about 200 insurance agents from around the country about properly assessing water damaged wood floors, as well as addressing the damage efficiently and effectively.”

Recovery from natural disasters is a long process, but with help from others around the country, and in our industry, progress will be made quickly. For information on how to help industry colleagues affected by the disasters, learn more at

4 thoughts

  1. I have been working on a personal project to save floor here in Houston. Of the 21 homeowners I have worked with all their floors were direct glue down to concrete and we saved everyone (so far) no matter what the amount of flooding. There were 12 others, some wood and most laminate, that were floated….we lost all of them. Wood floors went from 2 days under 6″ of water to 13 days under 5′ of water. As long as I have been in the industry this is the first time I had to calculate the long term viability of a floor based on water pressure related to the weight of water on the surface.

  2. Brett I really enjoy your article. Very well done with very useful information.

    My company specializes in drying hardwood flooring with a focus on restoring gym floors.

  3. An article such as this is excellent as it reminds us of many of the perameters we have to deal with. Another good article might be how to save flooded floors. That is the project I am working on as many here did not carry flood insurance as it had never flooded. It’s a good retirement project as it keeps my mind and body busy trying to use what I have learned in a lifetime. One key element I had not considered when I started this as it may be possible to save the floor structurally but end up with a health hazard either from the type of water the home was flooded with or the concern of getting mold in the wood flooring. All the wall timbers are treated for mold prior to rehanging wall board…but we can’t do that on or under a wood floor and that remains a concern I have. Any thoughts, experience anybody?

  4. Apologies Brett, I first read the article like it was guidelines for installation versus your purpose. Yes, using these methods one can save a floor. I do believe an added item would be to intentionally cut a row out to prevent a buckle, as reducing excessive horizontal stress either with mechanical fasteners or glue may well prevent areas loosening when the floor dries out. The reason we lost all of the floaters is that once they started buckling they took on more water beneath them and eventually many actually did float. Those few that only buckled slightly still could not be saved as they had to be removed to get the water out from under them and to dry the slab as they all used pads with high perm ratings.

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