How to Remove Moisture From Wood?

Remove Moisture From Wood

After a flood or spill, it is imperative to extract as much water from your wood floor as possible. Even waxed or sealed floors cannot withstand excessive water and if the wax or sealer is wearing out, the water can still seep into the wood. Leaving the water can cause irreparable damage to the wood as it is absorbed by the grain. The wood will first swell, then cup and buckle. Once buckled, replacement is the only option for repairing the floor.

  1. Pull up water-soaked carpets and remove furniture from the wet area. If the entire floor is wet, remove these water-soaked items from the house. Set them out in the sun to promote their drying while you work on the floor.
  2. Suction up as much water as possible using a wet vac. Empty the wet vac as it fills up to keep the suction strong and prevent the water from seeping back out. Continue suctioning along the floor, even when no visible standing water remains. The vacuum still pulls water from the pores of the wood that you cannot see.
  3. Scrub the surface of the floor with a scrub brush and a disinfecting cleaner that does not produce suds. Continue scrubbing until you remove all debris, oil, grease or other substances left behind by the spill or flood. Dirt and debris will hold the water on the floor and in the pores of the wood. Suction cup the water and dry the floor as you did before.
  4. Clean a second time with a wood floor cleaner to be sure all substances are removed from the floor. Use the scrub brush if necessary. If it is not needed, use a wood floor cleaning cloth or mop. Rinse the floor and then suction up the water and dry with cloths.
  5. Place a dehumidifier in the center of the room once all of the standing water is removed. Set it to the highest extraction setting possible. Turn it on and leave it running for at least 24 hours to pull moisture from the boards.
  6. Place fans blowing across the surface to further aid in drying the wood out. Turn the fans on the highest setting possible and situate them so that the entire floor receives air. Unless it’s raining, open the windows to bring in more airflow across the surface of the floor.
  7. Check underneath the floor, either in the crawlspace or basement, to ensure there is no water leaking through. Drill a small hole directly into the ceiling below the wet area to release any water that seeped down. Where only a little water is present, drill holes randomly across the area to increase airflow. For large amounts of water, cut a square out of the ceiling around the entire flooded area.
  8. Point fans directly at the ceiling to dry the wood and subfloor from underneath. Keep the fans on until the subfloor is completely dry. Test the area with the moisture meter. The floor is sufficiently dry when the meter reads between 8 and 14 percent moisture.
  9. Check for mold and mildew caused by the water once the floor is visibly dry. If found, scrub the floor with a mixture of six tablespoons of washing soda and one gallon of water. Rinse well and suction up the water from the floor just as you did before.
  10. Leave the dehumidifier and fans on in the room until the floor is completely dry. Check the wood using a moisture testing meter. The drying process can take several weeks depending on the current humidity and the level of moisture that was on the floor when you started.
  11. Replace the square you cut from the basement ceiling. If the piece you cut out dries and remains intact, then put it back and seal the joints with joint compound. Fill in drilled holes with spackling.

Kiln Drying

Freshly cut wood has a lot of moisture in it. Eventually, this internal moisture will evaporate by itself. However, kiln drying is used to speed up the process. Some of the unfinished wood you see on the market has been kiln-dried to reduce its water moisture content to around 8% so that it won’t suffer from moisture-related defects like warping and buckling. However, many building materials may have been dried down to about 15% moisture content.

But, that’s not the end of the story…

Wood moisture content is always varying. It’s never constant. Wood – freshly cut or kiln-dried – is always interacting with environmental moisture. Therefore, just because the wood is kiln-dried doesn’t mean it has lost the ability to absorb moisture. It will continue to absorb and release moisture until it comes into balance with the surrounding air.

What are Acceptable Moisture Levels in Wood?

The acceptable moisture levels of wood lumber can be in the range of 9% to 14% for exterior wood or for building envelope components within constructed assemblies. The acceptable moisture content in wood depends on two factors:

  • The wood’s final use.
  • The average RH of the environment where the wood will be used.

These two factors make it difficult to say anything specific about acceptable wood moisture content. It’s more important to understand that the wood is kiln-dried down to a certain bell-shaped range of MCs. There will be statistical outliers on both the low and the high end and you’ll want to catch these by using a quality moisture meter.