Waters Effect on Wood and Bamboo
Author: Terry Weinheimer (94 Articles)
Terry Weinheimer, resides in Oregon where he is a certified flooring inspector, floor covering consultant and educator.
The largest percentage of complaints when it comes to both wood and bamboo are moisture related. The moisture is usually due to a site related condition. Frequently a moisture problem is caused by conditions such as water under the structure, leaking pipe, excessively wet concrete or too much moisture in a buildings structural components at the time the floor is installed.
Improper maintenance also results in the introduction of excess moisture. The major component in many cleaning chemicals is water.
Water can have a detrimental effect on both wood and bamboo floors which are hygroscopic materials. When bamboo and wood are exposed to air their tendency is to either dry or gain in moisture. The loss or gain in moisture will continue until the material is in equilibrium with the humidity and air temperature. If too much moisture is gained these materials will swell and if too much moisture is lost they will shrink. While bamboo is somewhat more stable then wood in this respect, both are affected.
Wood is dimensional stable at its saturation point of 25–30% moisture content. Below this point it begins to shrink until it reaches 0%. As it starts to gain in moisture it expands until it reaches the saturation point again. Once back at the saturation point of 25-30% it again stabilizes.
When wood floors are manufactured it is kiln dried to an average of 6-9% Bamboo floors are usually kiln dried to 8-10%.
Both wood and bamboo when made into a floor are dried significantly below the saturation point. Once at this point the flooring is expected to stabilize with the environment in which it is installed. Since the floor still has a natural tendency to gain or loose moisture, it is imperative that the environment be maintained at a suitable level.
The expansion and contraction of floor material is not equal in all directions. As an example, a solid piece of wood that was over dried to 0% and allowed to increase to its saturation point of 28%, will increase by about 0.1% longitudinally or along the length/grain. The same piece of wood will increase 2 –8% perpendicular to the annular growth rings (racially or in strip width for flooring that is quarter sawn. If the floor is plain sawn flooring the increase will be parallel to the trees annular growth rings (tangentially or in strip width.)
With engineered flooring the expansion will be significantly less. The reason for this is that alternating layers of the laminate are prepared to run in opposite directions. Since they are not all running in the same direction they have a natural tendency to pull against one another, which helps to maintain stability. While the engineered floor is more stable in this respect, equilibrium moisture content still remains critical.
The moisture content of wood and bamboo that is in storage or installed at a point below its fiber saturation point has a natural tendency to fluctuate. This fluctuation is a result of changes in the relative humidity and air temperature within the environment in which the material is stored or installed.
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