Page 30 - Parquet International december 2014

ON FIELD
IN DEPTH ANALYSIS
SOURCES USED
- Standard UNI EN 1264-1/2/3/4
- Standard UNI 11371
dated September 2010: Wood and parquet flooring screeds – Properties and performance characteristics.
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These photos were taken during the second inspection
A ceramic floor had already been laid in the two bathrooms, while in the rest of the house (foyer, living room, kitchen, and three bedrooms), a solid wood floor in herringbone pattern - an element of notable prestige and quality - was scheduled to be laid.
Structural problems
Because the wood floor would be laid by to- tal gluing using a synthetic adhesive, the structural investigation of the laying surface was conducted by bearing in mind the con- tents of Standard a UNI 11371 dated Sep- tember 2010 Wood and parquet flooring screeds – Properties and performance charac- teristic. According to the Director of Works, the screed had been cast approximately three months prior to the laying of the floor but an instrumental check revealed that a moisture content of more than the maximum permissible 2% remained.
Furthermore during destructive testing, ag- gregates of hygroscopic nature had emerged, in other words, lightening materials, pre- sumably expanded clay; unfortunately how- ever, the company that had laid the screed had not documented its composition. In- vestigation also revealed that no vapor bar- rier has been inserted, and that the cement aggregate mix was absolutely brittle and in- consistent. What’s more, after the spreading of the concrete casting, the worker decided to also apply a layer of self-leveling agent over the surface of the screed that upon our inspection appeared to be clearly detached from the latter.
It was obviously impossible for us to learn the weight of the moisture content before the self-leveling agent was0 applied, but seeing the detachment that occurred, moisture lev- els must undoubtedly have been high in the laying surface. Stress tests demonstrated the presence of extended areas of self-level- ing agent that had already detached from the surface of the screed, most certainly due to the different hygroscopic shrinkage coeffi- cients of these two materials, which definitely compromised the possibility of laying a glued parquet floor.
During inspection, the concrete screed laid
in different rooms presented an evidently ir- regular and compromised structural situa- tion. These problems leave little room for doubt. Furthermore, on the whole, the screed did not even partially possess the perfor- mance characteristics summarized in Para- graph 4.2.2. Page 4 of UNI 11371:2010. Lastly, the presence of hygroscopic materi- al in the cement mix compromised the time required to reach a residual humidity value appropriate for parquet (2%), and the com- plete absence of a vapor barrier only made things worse . For this reason, in this case as well, as far as we were able to ascertain and measure, formed as it was, the screed was in- adequate to underlying a glued wood floor, also because it presented defects that pre- cluded its recovery even through the use of other products.
Starting all over again
In this case, the laying of the parquet floor onsite was possible only by completely dis- mantling the existing laying screed and re- doing it all over again, naturally after first checking the thicknesses remaining after re- moving the screed and choosing a product suited to its new formation, ideally a quick hardening material capable of shortening the execution times that had already been ex- tended far too long. As may be seen in the photos, it is simply amazing that such brit- tle and inconsistent screeds could be laid, without even going into the question of the absence of the vapor barrier, a function that appears to be entirely unknown to most peo- ple when instead it is just another simple product that can be very useful in the success of their day to day work. I