Overview
EN ISO 4157-1:1998 - Construction drawings - Designation systems - Part 1: Buildings and parts of buildings (ISO 4157-1:1998) defines a standardized approach to naming and coding buildings, spaces, building elements and components in construction drawings and documentation. Published by ISO and adopted by CEN as an EN standard, it establishes rules for designation codes to ensure consistent identification across design, construction and facility management workflows.
Key topics and requirements
- Designation structure: A complete designation combines a principal designation (category level) and additional designations (type, variant or individual identifier).
- Principal designation may be full text (HOUSE, ROOM), an abbreviation (H, R), numeric/letter codes or a reference to a classification system.
- Additional designations use letters and numerals (e.g., W12b) or running numbers (P1, P2).
- Definitions: Clarifies terms such as room, room name, room number and room identifier (I# prefix), including examples of nonβtraditional rooms (atriums, shafts, balconies).
- Buildings and parts: Guidance for identifying multiple buildings in a project (HOUSE 1, HOUSE 2) and parts of buildings (HOUSE 2 PART 1).
- Storey and floor numbering: Storeys are numbered consecutively bottom-to-top starting at 1 for the lowest usable level; 0 denotes the space immediately below the lowest usable level. National floorβnumbering practice applies for floor names and room numbering.
- Load-bearing elements: Recommended alphanumeric formats for structural elements (columns, slabs, walls, beams), typically four characters where initial digits indicate storey and trailing digits are running numbers (examples: C201, S202).
- Avoiding ambiguity: Requirements for indicating level differences (mezzanines, landings) and consistent application of numbering across staircases and half-levels.
Applications and users
- Architects and design teams - consistent labelling of rooms and elements on construction drawings and schedules.
- Structural and MEP engineers - clear identification of load-bearing elements, services and components.
- CAD/BIM authors and coordinators - enforce naming conventions and improve interoperability between models and documentation.
- Facility managers and asset managers - reliable room numbers and identifiers for maintenance, space management and lifecycle data.
- Contractors and surveyors - reduce errors during construction, procurement and handover.
Related standards
- ISO 4157-2:1998 - Construction drawings - Designation systems - Part 2: Room names and numbers.
- ISO 4157-3:1998 - Construction drawings - Designation systems - Part 3: Room identifiers.
Using EN ISO 4157-1:1998 helps organizations standardize construction drawings, improve communication across disciplines, and support efficient building operation and asset management. Keywords: EN ISO 4157-1:1998, construction drawings, designation systems, room numbering, building elements, ISO 4157.
