Wooden floors and humidity

Published on : 19 January 20215 min reading time

Many people know that wood “fears moisture”, or at least, in the case of excessive moisture, the wood expands until it swells, lifts or creates damage. In this article, we will try to explain why this happens.

Parquet and Moisture

In this article, we will see the importance of respecting wood, a material that can “get angry” and become dangerous if we don’t know how to treat it properly.

A wood floor swells under the effect of humidity, precautions to be taken to prevent this from happening and see what weather conditions are considered “comfortable” for wood flooring to remain intact for a long time. We will try to take a closer look at these problems.

The strength of a damp piece of wood

If I told you that with a small piece of wood, wet, you could detach marble blocks from a mountain, would you believe it? The expansion power of wood, due to humidity, is a phenomenon that has been known and used for years.

Before the advent of cutting tools and explosives, marble was extracted from quarries using wood.

The technique for extracting blocks from the mountain consisted, in fact, of making holes with chisels inside which wedges of dry oak wood were placed. Then the wedges got wet and the wood, swollen with water, expanded and caused the detachment of the marble blocks from the mountain. For this reason, when using the wood on the floor, it is necessary to take into account the capacity of the wood to expand in contact with water or in the presence of excessive humidity.  The most delicate moments are: humidity and expansion of the wood. Wood is a hygroscopic material.

And the water content within a floor varies continuously.

If the floor is too wet, it swells, increases in size and has the strength to cause serious damage.  Water also reduces the durability of the wood: expansion makes it vulnerable and its long-term strength is compromised.

Wood and water: enemies forever?

The main enemy of wood is water.  If wood is left in a moist environment for a long time, the basis for proliferation and subsequent attack by fungi, bacteria and insects that would not proliferate in a dry environment is laid. Parquet and woodworm are the biggest problems to be posed when the wood remains wet without being able to dry in an environment where there is also oxygen. In this case, the decay of the parquet continues unabated. And yet, during the life of the tree, water is a fundamental element for its growth and survival.

The transport of water from the roots to the canopy and vice versa takes place relentlessly through the tree’s stem fibers, which are very similar to many microscopic straws arranged vertically. On a spring day, a large tree can absorb up to 400 liters of water from its roots and lose 90% of its leaves through transpiration.

The presence of water in flooring products

When the tree is felled, the wood has a moisture content of more than 30%.

After transformation – to make your future parquet – the humidity level will have to drop to 10 irca: this is the humidity level that will contain the wood you will buy for your new parquet. To reach this level, the wood will have a tendency to shrink: as it loses water, it will also lose mass, therefore weight and size. But beware: in the event of variations in ambient humidity or domestic accidents, the size of the boards will vary, the wood may swell and “burst”, i.e. lift. For this to happen, a significant amount of moisture must be added to the floor. This is when the phenomenon of soaking occurs, which causes the floor to increase in size. This is what happened, for example, to the floor in the photo below, which leaked water due to a faulty skylight and swelled, deforming until it burst. Wood, regardless of the percentage of humidity it contains, always tends to balance its humidity with that of the environment in which it is located, reaching its “equilibrium humidity” or hygrometric balance. This is why it is said that “wood is a living material”, because it moves and contracts according to the humidity absorbed by the surrounding environment.

Wooden floors and humidity

Beware of the possibility of water infiltration through the roof (a skylight left open) or pipes . These are critical situations, events that could be called domestic accidents, the consequences of which are known. But in addition to avoiding these accidents, attention must also be paid to environmental conditions that could stress the floor in the long term. An uncomfortable environment (too hot and humid or too cold and dry) endangers not only your health but also the durability of a parquet floor.

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