How long does it take for my hardwood flooring to acclimate?
Acclimation is defined as the following: the process or result of becoming accustomed to a new climate or to new conditions.
When we are planning a new wood floor installation, we have to plan for sufficient acclimation time for the wood flooring. Why do we do this?
Wood is HYGROSCOPIC. A hygroscopic material is one that readily attracts water from its surroundings, through either absorption or adsorption, with the adsorbing substance becoming physically changed somewhat. When water vapor is absorbed, the water molecules are taken into the molecules of the substance, and changes such as increased volume can occur.
If you deliver a wood floor from a climate-controlled mill into a new home in August with no working climate controls and the hardwood flooring sits there for a week, it will swell up with the increase in moisture content. The boards will be expand and swell to their fullest capacity, their greatest dimensional measurements. Then they are installed in this state. What do you think will happen once the air conditioning is turned on and the relative humidity of the home is significantly reduced? That’s right, the boards will begin to lose their high moisture content and will shrink up/contract. You will be left with gapping (spaces between floor boards) that will never completely go away.
Here’s another scenario: If you bring a wood floor from a climate-controlled mill into an unocuppied home with no heating in January and it sits there for a week, it will shrink up because the moisture content of the wood will decrease with the dry air of the environment. The hardwood floor boards will be in their most contracted state and smallest dimensions. If they are installed in this condition, what do you think can happen once it is a more humid time of year? With a big increase in moisture content, the boards may swell and expand. Since they were installed in a contracted state, this swelling can put pressure on the floor because it is now a floor literally too big for the space. This may lead to cupping, crowning, or buckling.
Acclimation is the process of conditioning your hardwood floor boards so that their naturally occurring moisture content is at or near the moisture content of the environment where they will be installed. Acclimation gives your new floor boards the proper time to adjust to the climate conditions of your home. When we install a wood floor, we want to make sure that it is not moving. That the wood has reached its equilibrium moisture content (EMC): neither losing nor gaining moisture and is stable. As reviewed earlier, installing your wood floor before it has acclimated and reached EMC can lead to a host of problems down the road as displayed in the photos above.
So what do we advise for proper acclimation? To start, the conditions of the home must be closed and stable. Climate controls must be on and running for at least 5 days before wood flooring arrives. If climate controls are not installed and waiting for them would hold up a construction timeline, temporary AC or heating units can be used in particular situations to mimic the conditions of a normal, occupied home, but we would strongly prefer to avoid this situation if possible. Climate controls must be on and running during acclimation, during the installation, and after the floor is installed. Remember, once you make the commitment to having wood flooring in your home, you are making the commitment to keeping the conditions stable inside your home!
When the flooring is delivered, both the flooring and the subfloor should be tested for moisture content. Flooring should be spaced apart adequately so that air can circulate all around the boards. Remember that narrow planks “move” (expand and contract) less than wider planks.