The tolerances in building construction generally serve to limit the deviations from the nominal dimensions of the size, shape and position of components and structures. Adherence to the specified tolerances is necessary in order to perform the intended function despite the inaccuracies in measurement, manufacture and assembly that are unavoidable in the building trade. In addition to this, adhering to the dimensional tolerances also enables the functional assembly of structures and components of the building shell and extension.
In general, tolerances in building construction are specified by DIN 18202. It should be noted that this DIN for standard services or standard components and services have been designed for and only represent average types and dimensions within the scope of usual care to achieve the accuracies. It may well be that in special cases and despite compliance with the tolerance ranges, functions are not or only insufficiently fulfilled. In some special cases, the tolerances of standardization cannot be applied from the ground up and individual regulations must be made. If such cases occur, the necessary measures and corresponding control options during the execution must be determined in good time, at best already in the planning phase before the construction is carried out. In addition to this, values from load- and time-dependent deformations as well as temperature-related deformations must also be taken into account separately.
In the standard itself it is noted that the tolerances contained in the standardization are not exhaustive, however, the given values represent the general basis for fit calculations in construction. Thus, as a rule, the information is to be used by the construction experts as a guide to the type of control measurements (principles of the tests), but also as tolerance specifications within an appropriate framework.
In general, the following is specified in DIN 18202 “Tolerances in building construction”:
- limit deviations for dimensions
- limit deviations for angular deviations
- limit deviations for flatness deviations
- limit deviations for deviations from flight
As an expert office with a focus on construction defects and damage, tests to comply with the tolerances for structures and building components are the tasks that are carried out with almost every assessment. As a rule, we do this shortly before or during the acceptance test. However, an inspection during ongoing construction operations is more advantageous for everyone involved, because then the correction of possible deviations can usually be carried out more quickly and cost-effectively.
The costs for an expert activity in relation to the control of the construction tolerances are fundamentally dependent on the extent of the violations found, the necessary examination times and types of examination (e.g. measuring instruments) and the type of expert opinion requested, which are offered as follows:
- brief report with a brief explanation of the construction defects as the basis for out-of-court settlement or requests for improvement
- detailed building report for court reports, insurance reports, arbitration reports, evidence preservation procedures or similar
If the expert acts as a mediating construction expert, minutes of the conversation and / or results of the negotiations are also recorded. In all activities of the construction expert, it must be taken into account that the Holzmann-Bauberatung® expert office generally assumes a neutral position. The impartiality is confirmed in writing in every report.