Structural class 1 (KK1): control and documentation under DS1140

BR18 places load-bearing structures in a structural class based on three things: the consequence class under DS/EN 1990, the complexity of the structure and the experience with the type of structure (BR18 § 485). Under § 489, KK1 covers:

• All structures in the low consequence class (CC1).
• CC2 structures in detached, terraced, semi-detached and holiday homes with no horizontal division between dwellings, with no more than one storey below ground and two above.
• Simple, traditional CC2 structures in single-storey agricultural and operational buildings, and in single-storey industrial and storage buildings, with a span of no more than 40 m.
• Simple, traditional CC2 structures in statically independent buildings of up to 150 m², with no more than one storey below and two above ground, a span of up to 6 m and up to 30 people who can evacuate unaided, or single-storey with a span of up to 12 m.

If you’re unsure whether a structure is simple and traditional, BR18 says it must be treated as complex or unconventional (§§ 487–488), which can move the building into a higher class. Some small buildings, such as garages, carports, sheds and covered terraces up to 50 m², are exempt from the structural-class rules altogether (§ 489(3)).

For alterations, the work normally takes the class of the existing structure. However, simple, traditional alterations to existing simple, traditional CC2 structures can be placed in KK1 if the documentation is checked as for KK2 (§ 489(2)).

BR18 Annex 3, table 1 requires self-inspection only in KK1. The person who designed or carried out the work checks it. There is no requirement for independent or third-party control. The table of sample sizes for special control (table 2b) has no KK1 column.

A lower requirement doesn’t mean control can be skipped. Load-bearing structures must still be built correctly, and planned, documented self-inspection, for example following the principles of DS1140, is the best way to show that if questions come up later. See Self-inspection under DS1140.

BR18’s requirement for a start and final declaration from a certified structural engineer (certificeret statiker) applies to buildings in KK2–KK4 (§§ 496–499), not KK1. The structural documentation must still be prepared and correct. It just doesn’t need declarations from a certified structural engineer.

The documentation for KK1 is reduced (BR18 § 504). It covers:

• A1 Structural basis, including the basis for placing the building in KK1 (§ 503)
• A2 Structural calculations
• A3 Structural drawings and models
• A4 Structural changes
• B1 Structural project statement

The structural control plan (B2), control report (B3) and A5 as-built are not part of the KK1 package under § 504. See the bigger picture under Structural documentation.

• The class isn’t justified. The documentation must show why the building is KK1. “It’s just a house” isn’t enough.
• Doubts about complexity are ignored. Large spans, unusual solutions or new methods can make the structure complex or unconventional, and then it is no longer KK1.
• Alterations are treated as new builds. Alterations normally take the class of the existing structure.
• Self-inspection isn’t documented. Checks that only happened “in someone’s head” can’t be shown later.

If your building is close to the limit, see also DS1140 KK2.

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.