Structural class 2 (KK2): independent control and documentation under DS1140

Under BR18 § 489, structures in consequence class CC2 belong to KK2 unless they meet the conditions for KK1 or KK3. In practice, many ordinary residential, commercial and institutional buildings in CC2 end up in KK2 when they exceed the KK1 limits on storeys, floor area or span, and are not complex or unconventional.

For alterations, the work normally takes the class of the existing structure. However, simple, traditional alterations to existing CC3 structures in multi-storey buildings for long stays (such as homes, offices, hotels and day or residential institutions) with up to six storeys above ground and spans of up to 8 m can be placed in KK2 (§ 489(2)).

The structural class is set during design. In KK2–KK4, the certified structural engineer confirms in the start declaration that the classes have been chosen correctly (§ 498).

BR18 Annex 3, table 1 requires self-inspection and independent control in KK2. Independent control is carried out by someone who took no part in the design or execution of that specific work (§§ 526 and 526 a). BR18 doesn’t require them to come from another company, so this can be a colleague. See Independent control under DS1140.

Special rules apply to the execution in KK2 (Annex 3, table 1):

• Independent control must cover the execution basis for the work and be carried out by someone who does not work on the load-bearing structures.
• The rest of the control can be carried out by someone who was not involved in that control section.
• For smaller buildings, independent control of execution can be replaced by a check of the self-inspection documentation, if the building is no more than 300 m², 12 m high and 12 m wide and has one of the uses listed in the table (for example homes with up to two storeys above and one below ground).

BR18 Annex 3, table 2b sets a minimum sample of 10% for special control of the executed structure in KK2. Special control is additional control of particularly critical items, which are set out in the structural control plan for execution (B2). General control of the execution follows the control level in DS1140. So the 10% doesn’t apply to all control, only to the sample for special control.

In KK2, the documentation consists of a start declaration, a final declaration and the structural documentation (§ 496). Both declarations are prepared by the certified structural engineer (§§ 498–499). Since 1 January 2025, the final declaration covers the control of the design and the special control of the execution. General control of the execution is instead documented in a separate declaration at completion, stating that the control has been carried out and deviations dealt with (§ 41(3)).

The structural documentation (§ 496): the relevant parts of structural documentation A1–A5 and project documentation B1–B3 (§§ 500–502), including the basis for the classification (§ 503). For the contractor, that means in practice the Control plan under DS1140, B2 control plan, B3 control report and A5 as-built documentation.

• KK2 is treated as KK1. Only self-inspection is planned, and independent control is missing.
• The independent inspector took part in the work. Then the control isn’t independent.
• The small-building exception is used without checking every condition. Area, height, width and use must all be met.
• “10%” is read as the scope of all control. It only applies to the sample for special control.

We help main contractors, trade contractors and developers set up control that matches the structural class: from the control plan and self-inspection to independent control and the final handover package. We can take on the whole job or just the part you’re missing, anywhere in Denmark, and we explain the Danish requirements in English.

We can’t promise approval on anyone else’s behalf, and the formal classification and the certified roles sit with the responsible parties under BR18. But we make sure your control and documentation are structured, traceable and complete, based on the project material that exists.