Ulf Köpcke
Bibliographic info:
9th International BUILDAIR Symposium, 8-9 May 2015 Kassel, Germany

Purpose of the work

When it comes to evaluating the quality of building work, technical and legal perspectives often clash. This is probably particularly true when it comes to evaluating the airtightness of building envelopes. This presentation is an attempt at clearing up frequent misunderstandings and at formulating questions that would help to combine the technical and legal ways of assessing quality in the most practical manner possible.

Method of approach

As a starting point for further discussion, the presentation compares how definitions of quality and quality standards evolve and are used in technology and law.

Content of the presentation

Technical services – depending on when and where they are provided – always come up against objective limits. Whether a technical service is regarded as good or bad quality from the point of view of natural sciences is based on feasibility and usability as criteria. Such assessments, however, require suitable measuring instruments. This is why technology always has to clearly distinguish between inaccuracies in implementation on the one hand and in controlling on the other. In comparison, the legal assessment of quality mainly applies subjective criteria. After all, technical services and in particular services in construction are regularly provided by people for people. Only those who really come up with and implement a technical service all by themselves wrangle with the quality of their work at most. In all other cases, the people providing the service come into conflict with those contracting it, should the actual quality of implementation fall short of expectations. In legal conflict solutions, the contractual relationship between the parties involved, i.e. the specific content or the content to be specified as far as possible of the awarded contract is the final “measuring instrument”. What has been deliberated in the contract takes the place of technical feasibility, subjectively determined properties of use take the place of objective usability, and the technical measuring instrument used for quality control is replaced by the interpretation of the contract. The difference in the respective trains of thought alone bears a high risk for misunderstandings. However, we must always bear in mind that natural sciences and technology do not require any help from jurisprudence in order to carry out their quality control. On the contrary, legal conflict solution, according to our legal understanding, first always requires appropriate fact finding. This is why the application of law is frequently dependent on natural sciences. The fact that natural sciences in these cases only “service” the application of the law, does, however, not reduce the risk of misunderstandings.

Results and assessment

As a result, it must be concluded that the more exactly the quality of a construction service is defined in the underlying contractual relationship when referring to technical criteria of quality, the more amicable and unambiguous the legal-technical assessment of quality may turn out.

The more indistinct (“tolerant”!?) quality is defined in the contract, the more lawyers will have to rely on technical “tolerance” in implementation or metrological control in the application of the law. It is obvious that the latter constellation rarely leads to satisfactory results.


All this results in the following: legal quality control of construction services, for example of the airtightness of the building envelope, is all the more convincing, the better we are able to avoid having to fall back on any type of technical tolerance.


For more information, please contact the reference author at: koepcke.u@t-online.de