Page 30 - Parquet International December 2013

ON FIELD
A SURVEY
We have been able to verify the following: 1. The fitters did not nail down the floor – a stage required by and foreseen by the manufacturer and clearly indicated in its technical instructions provided with the DIN certification – in a manner compli- ant with the mandatory technical in- structions.
2. There are currently no sector-specific regulations regarding how such wooden parts should be nailed down (nor were there any before or at the time that the sports floor was laid). The only exception is the European technical specification UNI/CEN/TS 15717 dated October 2008 General Guidelines for Floor Laying, which, with regard to the laying of wood- en floors requiring nailing, reads: “the type of screws/nails must be selected in accordance with the manufacturer’s spec- ifications.”
In fact, as can be seen in the technical in- structions attached to the product certifi- cation documents, the manufacturer did provide specifications in this sense, i.e. 2.2x38mm T-nails should have been used to fix the parquet boards to the counter floor. Furthermore, one can assume that the fitters used the same non conforming nails to join the two load-bearing levels (the double oscillation joists and the counter floor) instead of the 2.2x32mm T- nails specified by the manufacturer.
3. The gaps between the parquet boards were caused by these boards slipping at the moment of impact (attrition) by the rubber-soled shoes worn by players dur- ing basketball games.
4. The complaint that the gaps between the boards “change their position”, as proven by the fact that certain boards open and then close after manual traction stress, confirms the fact that the type of nailing used, where present, and found to be non conforming with the official technical specifications, was insufficient to “withstand tension in the boards as a result of the surface friction.”
The heat coming from under the floor cannot be considered to cause the de- tachment of the boards (gaps between boards), despite the fact that the heat in the air-gap under the wooden floor is propagated solely by natural convection. 5. The gaps, in varying positions, only oc- curred at the extreme ends (heads) of the
boards and were of differing dimensions; these then “disappeared” if stressed, i.e. the boards were made to slide back and so close the gap.
The fact that these gaps regularly oc- curred can be further confirmed by the presence of “grouting substances” used to close the gaps and found at the ends of the boards.
There is no information about when the grouting substance was first applied, al- though certain photos lead one to pre- sume with a fair amount of certainty that the gaps started to appear between boards from the very time the court lines were first drawn on the floor.
6. The constant heat, as is the case with all heated supports where a wooden floor comes into direct contact with a hot sur- face, creates shrinkage in the wooden el- ements in a longitudinal direction only, to a varying degree depending on the timber used and the direction of its grain. For instance, wooden elements obtained from tangential-cut elements will shrink at least three times as much as radial-cut elements.
7. In the case in hand, we have only found localised gaps (in the playing areas) of varying dimensions at the front end of in- dividual boards; no similar gaps or oth- er deformations caused by shrinkage have been found across the whole surface of the floor. If the under-floor heating system had been the cause, we would have ex- pected similar problems across the entire surface of the wooden floor, not just in the playing areas, i.e. under the baskets.
CONCLUSIONS
To sum up, after several months of meet- ings, inspections and discussions, we have reached the conclusion that “nails were missing”.
The nailing of the floor was done in a dis- continuous manner, using nails that did not comply with the manufacturer’s in- stallation instructions and this saving in nails led to a whole series of incredible problems that required the intervention of many experts.
Was it really worth it?
We hope that this case will serve as a les- son when facing similar jobs in the future. The old adage “the cheapest is the dear- est” has been proved true once again. s