Brief definition
Cost group 400 under DIN 276 comprises technical installations (heating, ventilation, plumbing, electrical, conveying systems, etc.) — separate from building structures (KG 300).
Relevance for quantity take-off
Many KG 400 items are represented via bills of materials, pipe runs, and connections. Floor-plan geometry alone does not cover all KG 400 quantities; it is nevertheless the starting point for interfaces and coordination with KG 300.
Normraum relevance
KG 400 quantities come from bills of materials and pipe lengths that an architectural floor plan does not carry – Normraum does not deliver them. What comes from the as-built plan is the room structure: the room book with use and area per room under DIN 277, with confidence score and source reference, on which sizing and coordination with KG 300 build.