Hello "faddl92". As a technical layperson, one must recognize the moment when a specialist must take the stage to review the circumstances and properly assess them. In principle, your previous approach, as I see it, was chosen correctly! A contractor installs something, you criticize the execution and grant a correction, which in this case concerns an already visually noticeable, slight screed coverage of the heating elements of an underfloor heating system. Whether the correction now made is sufficient and the current condition can be accepted, I cannot judge from a distance. However, if the boiler pressure of the heating system continuously decreases and the screed in the corrected area appears damp (this can be determined with simple testing devices), then you should indeed request other professional help. A lawyer, as " " recommended, will (in my many years of experience) not prove useful at least in the initial stage, as this professional group often represents an independent "problem" and cannot contribute to technical solutions. [Note: the ideal is always cooperation between lawyer/technician] The correct path would therefore be, before the situation you described arises, as already recommended elsewhere, specifically engaging an expert of the affected trade (screed or floor technology). In this context, this expert must also examine whether the repaired (or badly repaired?) spot was the only one in the entire area or whether a relevant undercoverage must be assumed. Meaning: check the screed coverage area-wide! My additional recommendation would be to inform those responsible (for example the general contractor) of the expert’s site inspection and also invite them to attend. Tip: If the expert arranges this, experience shows that the necessary pressure on the matter will come from the parties involved! Well, this also requires an expert who understands their field and who does not "give in" on site under pressure (often half-truths expressed on site), who knows and masters the technical rules. In summary The point, in my view, has been reached where the fun stops. If it should be confirmed that the screed is not load-bearing due to insufficient coverage, not only must tests (and decisions) be made that are court-proof later, but everything must also be documented accordingly! Through a private, yet later court-admissible, evidence collection, delays in the construction schedule can be kept minimal. Otherwise, one must (currently estimated) wait about 1.5 years until a court, after endless exchanges of letters between lawyers, appoints an expert who may again need several months of time to visit the object, until they then issue the report after further weeks. The content statements of which, of course, as practice shows, are disputed and lead to endless inquiries via the court. The current condition in your property is estimated to remain so for the next 2 to 3 years. A private evidence collection via an (definitely publicly appointed) expert saves considerable time—and certainly money. Even if the colleague will not work for free :) ---------------------------------- Wishing you a good decision: KlaRa