Page 22 - Parquet International luglio 2014

ON FIELD
8
7
IN DEPTH ANALYSIS
1) Moisture content of the wood laid.
Taking into account the time factor, or rather the amount of time that had passed from the completion of laying and the application of the protective finishing until the day that thee anomalies in the wood floor were dis- covered, it is much likely that the problem was caused by a poor adhesion of the glue, which therefore proved incapable of con- taining the anisotropic movements of the boards after they had absorbed the humid- ity in the environment. We should also re- member that this residential unit was being subjected to a large-scale building renova- tion, and therefore the rooms might have contained more moisture than the values usually indicated in product technical doc- umentation. Often, and unfortunately how- ever, operators tend to forget a process from which wood floors can never be immune: the property of dynamic hygroscopic bal- ancing. In the case at hand, a moisture con- tent just barely above the maximum value specified by the product's reference standard was measured in the wood. No flooring planks still in their original packaging were available onsite for a check on the moisture content estimated and a comparison with the moisture content effectively measured after the passage of time. In any case, I be- lieve that due to the absence of dimension- al deformation or any increase in width of the planks composing the wood floor, prob- lems caused by the flooring wood as origi- nally supplied can be reasonably excluded.
2) Scarce adhesion and grooving of the glue not suited to the wood's format.
The gluing test performed manually using a 500 g stiff plastic mallet provided a hollow thudding sound in over 50% of the floored surface, while also considering that it was conducted only and exclusively on planks laid in walkable areas.
The gluing procedure could not be exam- ined and consequently neither could the di- rect anchoring of the wooden plans be checked and whether or not they were laid to in respect of the sector's state-of-the-art at the moment. In particular, the distribution of the adhesive, in other words, the height of the top of the “grooves” was absolutely not proportionate to the large size of the planks. This led to an inadequate contact be- tween the adhesive and the parquet's bot- tom layers, to the extent that there were nu- merous planks lifted up in which adhesive was completely missing from the underside. The glue - of excellent quality, by the way, had reticulated correctly, but as may be seen in certain photographs, the glue was dis- tributed unevenly on the bottom layer, in such great quantity in some areas that when we pulled up the plank some of the concrete laying surface was still attached (Photo 7). On the other hand, there were other areas in which the glue laid on the support surface had not even been touched by the plank laid on top. This clearly shows the height of the top of the adhesive's grooves left by the spat- ula had been too low.
Furthermore, the imperfect planarity of the laying surface - combined with the dimen- sions of the wood planking used - also played an important role in this dynamic and contributed to the raising of parts of the floor (Photo 8). For this reason, despite the abundant quantity of adhesive spread over the concrete support surface, the wood floor could be raised up without requiring much effort at all.
It must also be borne in mind that this rais- ing is not intended as the detachment of the floor from the laying surface as the result of any increase in dimension but rather the fact that the floor was almost completely de- tached from the laying surface without any sign of deformation: if it had been possible