DIN 18202: tolerances in building construction
DIN 18202 (the German standard for tolerances in building construction) defines which dimensional and flatness deviations are permissible in building construction, for example for walls, floors and ceilings, and openings. It is therefore the usual yardstick against which a target/actual comparison is run when the project does not set its own, stricter requirements.
A deviation only means something together with its tolerance
A deviation of two centimetres is not a finding. It can be well within what is permissible or clearly above it, depending on which component is concerned and over which reference length it was measured. The standard works with limit values that grow with distance: what would be impermissible over one metre is normal over ten metres.
This gives the rule for every deviation report: every value comes with a statement of the tolerance it was checked against. A colour-coded deviation map without this statement shows differences, but not defects.
Where it comes up in a project
- In the as-built comparison, when the built condition is set against the design.
- In construction progress documentation, where what will later be checked against is defined before the first survey.
- At the acceptance of shell and fit-out work, when it is disputed whether a deviation has to be accepted.
When the project sets stricter requirements
The standard is the fallback, not the upper limit. Where prefabricated elements are installed, facades are connected or plant is set up, tighter tolerances from the contract or from the trade regularly apply. They take precedence over the standard, and they belong in the agreement before anything is measured — not in the discussion about whether the measurement result is correct.
Frequently asked questions
What does DIN 18202 cover?
Permissible dimensional and flatness deviations in building construction, for example for walls, floors and ceilings, openings and prefabricated elements. The limit values depend on the component and on the reference length.
Is a measured deviation of 2 cm a defect?
That cannot be said without a reference. Only with the component and the reference length does the measured value become a statement. That is why every deviation report names the tolerance it was checked against.
Does the standard always apply?
It applies wherever nothing stricter has been agreed. Contractual or trade-specific tolerances take precedence and are defined before the measurement.