| 50 | 500 | | BUILDING AND CIVIL ENGINEERING General building and civil engineering work (without any particular specialisation) and demolition work |
| | 500.1 | General building and civil engineering work (without any particular specialisation) |
| | 500.2 | Demolition work |
| 501 | | Construction of flats, office blocks, hospitals and other buildings, both residential and non-residential. |
| | 501.1 | General building contractors |
| | 501.2 | Roofing |
| | 501.3 | Construction of chimneys, kilns and furnaces. |
| | 501.4 | Waterproofing and damp-proofing |
| | 501.5 | Restoration and maintenance of outside walls (repainting, cleaning, etc.) |
| | 501.6 | Erection and dismantlement of scaffolding |
| | 501.7 | Other specialised activities relating to construction work (including carpentry) |
| 502 | | Civil Engineering: construction of roads, bridges, railways etc. |
| | 502.1 | General civil engineering work |
| | 502.2 | Earth-moving (navvying) |
| | 502.3 | Construction of bridges, tunnels and shafts, drilling |
| | 502.4 | Hydraulic engineering (rivers, canals, harbours, flows, locks and dams) |
| | 502.5 | Road-building (including specialised construction of airports and runways) |
| | 502.6 | Specialised construction work relating to water (i.e. to irrigation, land drainage, water supply, sewage disposal, sewerage, etc) |
| | 502.7 | Specialised activities in other areas of civil engineering. |
| 503 | | Installation (fittings and fixtures) |
| | 503.1 | General installation work |
| | 503.2 | Gas fitting and plumbing, and the installation of sanitary equipment |
| | 503.3 | Installation of heating and ventilating apparatus (central heating, air conditioning, ventilation) |
| | 503.4 | Sound and heat insulation, insulation against vibration |
| | 503.5 | Electrical fittings |
| | 503.6 | Installation of aerials, lightning conductors, telephones, etc |
| 504 | | Building completion work |
| | 504.1 | General building completion work |
| | 504.2 | Plastering |
| | 504.3 | Joinery, primarily engaged in the after assembly and/or installation (including the laying of parquet flooring) |
| | 504.4 | Painting, glazing, paper hanging |
| | 504.5 | Tiling and otherwise covering floors and walls. |
| | 504.6 | Other building completion work (putting in fireplaces, etc.) |