Building systems are the constituent parts of a building or built asset, including, but not limited to, structural systems, mechanical and electrical systems, facades, and ceiling, floor and wall systems.

The term is used in NRM 1 when describing how design information develops. Each building system is designed either by the design team or by a specialist subcontractor, and the QS needs to understand which, because it affects how much detail is available for cost planning and where design risk sits. Breaking a building into systems also helps align the cost plan with the way the work will be procured in packages.

Related terms: construction information, descriptive information, element, work package.