CPV code 45213400 designates Installation of staff rooms in the Common Procurement Vocabulary (CPV 2008), the EU classification used to describe the subject of public contracts.
45213400 is a leaf code — the most specific level of its branch — so it can be used directly as the main CPV code of a contract notice. If it does not quite fit, check the neighbouring codes under 45213000 (Construction work for commercial buildings, warehouses and industrial buildings, buildings relating to transport).