Krimpen en zwellen

By 'working' wood we mean the shrinking and swelling of air-dry wood as a result of normal changes in relative humidity. If the wood loses even more moisture from the fiber saturation point, this must come from the cell walls, causing them to deform. The wood will then shrink. On the other hand, when wood absorbs moisture below the fiber saturation point, it swells. The speed and strength of these shape changes depend on the wood specie .

The fiber saturation point

Shrinkage and swelling in wood only occur below the fiber saturation point. Above the fiber saturation point, the size of the piece of wood remains the same with varying moisture contents. The fiber saturation point varies between 20 and 36% for different wood species .

The average value is often used as 27%. To avoid excessive shrinkage, the wood must be dried to a moisture content that is the same as the average relative humidity of the environment in which it will be placed.

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Direction of shrinking and swelling

The shrinking and swelling of wood does not occur equally in all directions of the wood. The shrinkage in the longitudinal direction (direction of the fibers) is usually negligible in practice.

Perpendicular to the fiber direction, the shrinkage is greater, with the wood shrinking and swelling approximately twice as much in the direction parallel to the growth rings (tangential direction) as in the direction of the rays (radial direction). This ratio can vary greatly for different wood species .

In general, heavier wood species work more than lighter ones. The working of the wood is also highly dependent on growth tensions and irregularities in the wood. The result can be; warping, torsion or cracking.

Due to the weather and the seasons, wood is usually exposed to changing relative humidity and therefore to shrinking and swelling. A typical example is the door that gets stuck in a humid season and functions normally again in a drier period.

Wooden floorboards and humidity

When you are going to install wooden floorboards, you should take the humidity of the room into account. The ideal humidity is between 45% and 65%. You can measure the humidity using a hygrometer.

When installing a solid wooden floor, it is always taken into account that the wood continues to work. That is why a space is always left along the sides (swell space) so that the floor can adapt to the humidity within the room.

If the humidity in the room where the solid planks are located becomes too high, the floor can expand so excessively that the solid plank floors becomes stuck between the walls, causing the floor to bulge.

If the humidity in the room is too high, you must ensure that there is good ventilation and that the temperature in the room where the floor is located is higher than the temperature outside. If the humidity in the room where the solid wooden floor is located is too low, you can maintain it by purchasing a humidifier.

A characteristic of too low humidity is that the floor will shrink in the working width. With low humidity, the floor can also make noise when you walk on the floor.

Frequently Asked Questions

Why does a wooden floor shrink and swell?

Wood responds to changes in humidity and temperature. At higher humidity the wood will absorb moisture and expand, while at lower humidity it will lose moisture and shrink.

How can I minimize the shrinking and swelling of my wooden floor?

Maintaining a constant humidity and temperature in the room helps to reduce shrinking and swelling. Use dehumidifiers or humidifiers as necessary to maintain ideal humidity levels.

What is the ideal humidity for wooden floors?

In general, a humidity level between 50% and 70% is considered ideal for wooden floors. Too high or too low humidity can cause problems such as warping, cracking and loosening of planks.

What are the signs of shrinking and swelling in a wooden floor?

Shrinking can result in gaps between the planks, while swelling can lead to bulging or warping of the floor. Creaking sounds can also occur when the planks move.

How can I deal with shrinking and swelling in my wooden floor?

Make sure the humidity in your home is properly controlled. Also do not place heavy objects on the floor that could hinder shrinking. In extreme cases of shrinking or swelling, it may be necessary to consult a professional flooring installer.

Is engineered wood flooring more sensitive to shrinking and swelling than solid wood floors?

Engineered wood flooring is generally less sensitive to shrinking and swelling than solid wood floors. This is because an engineered wood floor consists of several layers of wood, with the top layer usually made of hardwood that is less sensitive to moisture changes.