Page 26 - Professional Parquet July 2013

ON FIELD
THINGS TO PAY ATTENTION
To achieve long-lasting and beautiful results, it is important to pay attention to several factors: an adequate project, appropriate specifications, wood quality and correct installation. As much as it is important to select a durable wood in itself (or a wood that has been treated with additives under pressure to ensure its durability), it is equally important to adopt good practices in the "construction". To avoid the risk of deterioration due to fungi, which might occur if the wood remained at high moisture content (above 20%) for an extended period, it is important to avoid the accumulation of water and make sure that the surface water drains away easily. A sufficient natural ventilation of all the elements is generally the most effective way to avoid high moisture content in the wood. To improve the non-slip effect, we also recommend the use of structured or grooved boards. Exposure to ultraviolet sun rays causes discoloration on the wood, but it can be avoided by treating it with fixatives and pigments. To avoid staining of the wood caused by corrosion due to metal finishes, such as; screws, nails, clips, foils and forks, and to make sure that these stains would not deteriorate, it is recommended to use stainless steel for exposed parts and hot dipped galvanized steel for the hidden parts.The wood tends to "move" with the variation of its moisture content, in order to improve the robustness and stability, the humidity level should not exceed 20% during the installation.
IN-DEPTH ANALYSIS
The behavior of the outdoor wood
The wood is not a homogeneous mater- ial. Its structure consists of a set of cells each of which has a distinctly elongated structure; adjacent positioning of these cells gives the wood a well-known mor- phology (the common wood fiber).
The cells have walls of lignin, i.e. a semipermeable substance inside of which features a certain quantity of wa- ter; hence the ratio between the quanti- ty of water contained and the dry weight of the wood material is defined as humidity of the wood. This moisture reaches to an certain level in relation to the condition of humidity and tempera- ture, or more properly the relative hu- midity of the surrounding environment such a way that if these conditions re- main constant, the humidity of the wood will remain constant, whereas if it alters, the moisture content in wood changes as well, particularly, the rela- tive humidity will increase when the surrounding humidity increases, and vice versa. Each variation in moisture level involves a variation in dimensions of wooden element, which differs de- pending on the direction in space. In particularly, the variation in the longi- tudinal direction of the cells, more pre- cisely in the sense of the fiber, in com- parison to the other two directions and among both which is almost absent. The tangential is greater than the radial. This then validates the rule that if the humidity increases the size increases as well, and vice versa. The wood is there- fore subject to dimensional variations
as a result of periodic cycles of external situation; normally the withdrawal phenomenon is normally partly recov- erable and, beyond a certain threshold, it is also irreversible.
The behavior of a wood element may be different on both surfaces depending on the exposure to air and direct irradi- ation of the sun: the upper surface ex- posed to the sun will tend to dry out more quickly than the lower surface in the shadow. Therefore, the planks may have an inhomogeneous withdrawal behavior, with a narrowing more marked on the upper surface, which leads to a decrease in the size, resulting convexity of the surface.
In conclusion...
Each time you want to use the solid natural wood, it is necessary to assess the technical properties that character- ize and diversify the multiple wood species and, in case of parquet laid out- doors, one has to take into account (and tolerate) some limitations that are im- possible to overcome: such as; the gray- ing, the whitening, the formation of cracks and capillaries, the color change in the wood due to the continuous vari- ation of the ambient weather condi- tions, as well as some dimensional dis- tortion of the laid element.
Like all other types of flooring, even the ones for outdoor insulating against the heat, cold, noise and moisture, it has ideal qualities of resistance and stability and for maintenance without any re- quirement for any special attention. s