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Weatherization and Kiln Drying of Wood Floors: What You Need to Know!

Wood flooring is a delicate product, as it is a natural product that expands and contracts with seasonal changes and is also affected by the moisture content of the air. It is important to remember that it has nothing to do with other types of flooring, such as mosaics or carpets, since wood is an organic material that will be affected by the surrounding climate.

Acclimation is ensuring that wood flooring boards are ready to be safely installed, it is the process of allowing the moisture content of hardwood flooring to partially equalize when supplied, with the moisture content of the surrounding environment where it is installed. wood will be installed.

The moisture content of wood can be defined as the percentage by weight of water present in the wood compared to the weight of the wood with all the water removed. The moisture content of a wood varies with changes in temperature, the humidity in the air in which the wood’s climate is located. Small seasonal changes in hardwood floors are considered normal, and small gaps that open up during dry spells are not considered a defect. In theory, tables that can be opened in the hottest periods of the year will close in the coldest and most humid times of the year.

wood supply

Many customers of wood flooring companies may fall victim to purchasing wood that has not been kiln dried and settled, so the path will result in unavoidable shrinkage or cupping depending on whether the wood is too heavy. dry or too wet. To minimize movement of your wood flooring caused by swelling with moisture absorption and shrinkage with moisture loss, it is important to lay boards that have a moisture content close to the average for the environment in which they will be placed. This can only be achieved when the supplier properly dries the wood in a kiln, which involves a lot of time and care to ensure that the boards have dried as naturally as possible and are not unstable, which occurs when drying of wood accelerates. some larger corporate companies.

When choosing your wood, request certificates of authentication for moisture content from your contractor or floor builder to make sure the wood you’re paying for is worth it.

Engineered (prefinished) hardwood floors are sealed sooner and tend to be much more stable in regards to changes in humidity than raw organic solid floors that have not been sealed. Therefore, acclimation is not needed when installing engineering boards.

site assessment

All construction or residential sites require a climate assessment prior to the installation of a hardwood floor. It is important to know the long-term relative humidity for the area where the floor will be installed, for example, if you acclimate a wooden floor for a house in the rainy season, you will find that in the hottest seasons the floor will dry out and shrink. so it’s good to keep a fair balance. Relative humidity (RH) is the primary influence that determines whether solid wood floors will absorb moisture from the air and swell, or lose moisture and shrink.

For some, if the moisture content of the wood floor is close to the long-term average relative humidity for the area, subsequent seasonal changes will be minimal. However, if the long-term relative humidity of the area is significantly different from that of the wood floor, seasonal changes in the moisture content of the floor can create problems. Sometimes your state weather forecast office can find local site climates for your area. For example, for Australia, the site climate can be assessed using data from the Australian Bureau of Meteorology website at

Where seasonal variations are greater, seasonal movement (shrinkage and swelling) can be expected to be greater as well. Areas that experience high levels of seasonal variation require a higher allowance for floor expansion at the time of installation.

The construction site or job site should also be assessed for adequate subfloor ventilation. This is a very important factor in reducing expansion and slump in hardwood floors. When the humidity under a floor remains high, the boards will hollow out the surface where you walk as a result of the wood absorbing moisture from the humid air below. Wood is like a sponge, it absorbs water and spits it out just as quickly.

Percent moisture content of its states

It is important to note the correct moisture content percentage for the geographic location you are in. The wood flooring contractor you employ usually knows a base or general figure, and it varies between 6-10% from state to state in the US. In Australia, the moisture content of the wood also depends Whichever state you’re in, for example, Western Australian residents should expect a humidity percentage of around 9-11%, in the Eastern States that figure changes to 11-13%, which is quite large. amount. When the average supplied moisture content of the floor is close to the expected moisture content of the area where you live, it is not necessarily necessary to acclimate your floor. As the process has already been completed by the wholesaler.

Where conditions are drier, such as isolated indoor areas or air-conditioned buildings, or where conditions are humid, such as coastal areas or higher elevations, on-site acclimation of the flooring may be necessary. The proper time frame for acclimating wood for that job is 2-4 weeks, not 3-6 days as some may think.

Board stacking to ensure acclimation to moisture

When storing wood flooring boards to acclimate for that job, if the wood is stacked on top of each other, the wood in the middle of the stack will not be able to breathe, therefore only the outer boards will change their moisture content to adapt to the environment. humidity and conditions. Please note that the rate of moisture absorption varies from species to species.

A crisscross method is recommended to ensure that all boards receive good air ventilation so that when the flooring boards are installed they are all ready and not unstable in their environment.

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