ᐅ What is underneath the flooring?

Created on: 5 Jan 2016 22:36
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pulsar86
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pulsar86
5 Jan 2016 22:36
Hello,
I started removing the flooring in our living room today. It’s not easy because the floor is very old and was glued down. Underneath the flooring, there is a black layer, similar to tar. Could it be tar, or what might it be?

Maybe someone can help me out.
Thank you

Wooden board lying on dirty concrete floor with black oil stains and wood chips.
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Elina
6 Jan 2016 00:36
This will be the screed, most likely poured asphalt. We had that as well.
wpic6 Jan 2016 11:44
[Caution!] This could be a tar-based parquet adhesive or a cast asphalt screed. Both materials contain PAHs (polycyclic aromatic hydrocarbons), which are known to be highly carcinogenic. Since these substances are firmly bound, they do not pose an immediate risk. PAH compounds usually enter the body through food, and in some cases, they can be absorbed through the skin due to their fat solubility. There are no established exposure limits for PAHs.

Until the 1960s, it was common to use PAHs in tar-based adhesives for laying parquet floors. These were later replaced by newly developed synthetic resin adhesives. However, tar adhesives were still used for wooden block paving until the 1990s. To be absolutely sure, you can take a sample and have it analyzed.

PAH-containing adhesive must never be removed as a DIY project. Protective measures must be observed, and the removal process should follow TRGS 524 (Technical Rules for Hazardous Substances / Protective Measures for Work in Contaminated Areas). The company performing the removal must demonstrate the necessary qualifications and protective measures in advance. Proper documentation of disposal is also required.

If possible, the adhesive should remain undisturbed on the floor. Mechanical treatment (such as sanding) is strictly prohibited due to the carcinogenic dust it generates.
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pulsar86
6 Jan 2016 13:39
When removing the flooring, some of the black adhesive remains on the concrete floor, while other parts stick to the flooring itself. In theory, is it possible to install new flooring over this without exposing oneself to health risks?
wpic6 Jan 2016 13:50
Why are you removing the floor covering? If it adheres well to the screed and is level, a new covering could be installed or glued over it. If there are issues with the build-up height, it may, of course, need to be completely removed. The floor covering, including any adhesive residue, is classified as special waste and must be disposed of accordingly. The PAH (polycyclic aromatic hydrocarbons) adhesive residues remaining on the floor must be leveled with suitable filling compound or self-leveling underlay before applying the new floor covering. All components need to be compatible with each other. Expert advice is also recommended before starting the refurbishment. So: first research and check, then consider/ask for advice, then build. In this order. It is more cost-effective.
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pulsar86
6 Jan 2016 14:22
The flooring adheres well to the screed but needs to be removed because otherwise, there will be too many height differences. You mentioned earlier that these need to be removed by a company. Now you have mentioned that they can be leveled out with suitable filler material. When would there be a health risk for me?