hello,
I found the following article on isp:
Assessment criteria for installed parquet floors
Based on the DIN standards and SIA 253 / 753, ISP has created the following assessment criteria:
1. The visual assessment must be made standing on the parquet surface to be inspected.
2. The local lighting conditions (e.g. window fronts down to the floor surface or only roof windows) must be taken into account for the visual assessment.
3. Extreme light sources (e.g. lamps placed specifically for assessment on the floor surface) must not be included in the visual assessment.
4. The properties of the different types of wood and cuts as well as the properties of the various surface treatment methods must be considered in context.
5. The finished surface-treated parquet must not show disturbing sanding marks.
6. Sealed surfaces must have a uniform gloss level.
7. A few processing-related impurities in the surface treatment are to be tolerated.
8. The manual work performed with movable devices on the construction site (e.g. edge sanding) must be assessed from a technical expert perspective.
9. Isolated hollow spots in fully glued parquet floors are permissible:
- up to a maximum of 1/3 parquet element length in the largest diameter of the hollow spot, if a tongue/groove or tongue and groove connection exists, or
- a maximum of 10 – 20% of the surface of the individual parquet element with butt joints.
- Detached areas must not be movable in height.
- A re-bonding effect caused by the parquet glue when stepping on or unloading must not occur.
- The local position and frequency of the hollow spots must be taken into account.
10. Overlaps/height differences in engineered parquet may be max. 0.2 mm between the individual elements.