The following four steps will guide you through the execution class selection process:
1. Define the consequence class
2. Select a service category
3. Select a production category
4. Use the results of steps 1, 2 and 3 and a matrix to determine your execution class.
1. Define the consequence class
The purpose of defining a consequence class is to ensure that buildings (and other structures) are constructed with the appropriate level of quality control. Consequence classes are based on building type, building height (number of storeys), floor plan area per storey (for retail) and occupancy. A structure, or a part of it, could also contain components with different consequence classes. In most cases, CC2 will be suitable.
Class |
Description |
Examples* |
CC3 | High consequence | Stadiums and concert halls for 5,000+ people, buildings storing hazardous substances |
CC2 | Medium consequence | Most multi-storey residential and commercial buildings, hotels, hospitals, education establishments and car parks |
CC1 | Low consequence | Agricultural or storage buildings |
2. Select a service category
Service categories reflect the risk arising from the actions to which the structure and its parts are likely to be exposed during erection and use, such as fatigue and likelihood of seismic actions. They also look at the stress levels in the components in relation to their resistance.
Service categories are determined from Table B.1 of BS EN 1090-2. In the UK, for instance, SC1 will generally be appropriate.
Category |
Criteria |
SC1 | Structures/components designed for quasi actions only, e.g. buildings |
SC2 | Structures/components designed for fatigue actions to EC3 such as bridges, or located in regions with medium/high seismic activity |
3. Select a production category
Production categories are determined by the risk arising from the fabrication complexity of the structure and its components. This may entail the application of particular techniques, procedures and controls.
Production categories are determined from Table B.2 of BS EN 1090-2 and it should be noted that a structure or part of a structure may contain components or structural details that belong to different production categories. However, the execution class is not always sensitive to the production category.
Categories |
Criteria |
PC1 | Non-welded components or welded components from steel grades below S355 |
PC2 | Welded components manufactured from steel grades from S355 and above |
4. Use the results of steps 1, 2 and 3 and a matrix to determine your execution class
Once the consequence class, service category and production category have been determined for a building, Table B.3 of BS EN 1090-2 defines the corresponding execution class. In the UK, for instance, EXC2 will be applicable to most buildings. Where no execution class is specified, Clause 4.1.2 of BS EN 1090-2 states that EXC2 applies.
Consequence class |
CC1 |
CC2 |
CC3 |
||||
Service category | SC1 | SC2 | SC1 | SC2 | SC1 | SC2 | |
Production category | PC1 | EXC1 | EXC2 | EXC2 | EXC3 | EXC3 | EXC3 |
PC2 | EXC2 | EXC2 | EXC2 | EXC3 | EXC3 | EXC4 |