Overview
ISO 6284:2023 - Technical product documentation - Construction documentation - Indication of limit deviations - specifies standardized methods for showing limit deviations on construction documents. The third edition updates guidance to support both traditional graphical drawings and machine‑readable data templates (BIM), and clarifies types and notations for upper and lower limit deviations relative to a target size.
Key topics and requirements
- When to indicate deviations: Limit deviations are required only where a functional requirement exists to control position, dimension, orientation or form.
- Reference convention: The target size is the sole reference for expressing deviations; upper and lower limit deviations are signed values.
- Two indication methods:
- Dimensions on construction drawings - numerical indications placed with or adjacent to the concerned size; use millimetres or metres for linear sizes. Symmetrical tolerances use ±, zero must be shown explicitly as “0”, angular tolerances may be given in decimal degrees or degrees/minutes/seconds.
- Property items in data templates (BIM) - limit deviations represented as structured property groups for machine‑readability.
- Property items required (for data templates): DeviationType, ReferenceTo (if applicable), DesiredValue (e.g., TargetSize/TargetAngle/TargetXCoordinate), UpperLimitDeviation, LowerLimitDeviation. The standard recommends using PascalCase naming for properties.
- Deviation type designations: common abbreviations are provided (e.g., LD = Length deviation, AD = Angular deviation, PL = Profile/Position deviation of a line, SL = Straightness deviation, SS = Shape deviation, FS = Flatness deviation, SK = Skewness, PP = Position deviation of a point, VD/HD = Verticality/Horizontality).
- Presentation rules: Examples illustrate asymmetrical vs symmetrical tolerances, positional tolerances for locating objects, profile and straightness deviations, and how to number or provide coordinates for points.
Practical applications
- Ensures consistent, unambiguous tolerance and deviation information in construction drawings and digital models.
- Supports quality control, prefabrication coordination and site installation by defining acceptable limits for manufactured elements and on‑site work.
- Facilitates interoperable exchange of tolerance data in BIM workflows and automated checking or fabrication processes.
- Useful for drafting CAD standards, preparing factory/fabrication packages, and specifying inspection criteria.
Who should use this standard
- Architects, structural and civil engineers
- CAD/BIM managers and modelers
- Manufacturers of prefabricated building components
- Contractors, quality inspectors and surveyors
- Standards writers and technical documentation specialists
Related standards
- ISO 286-1 (tolerances and deviations on linear sizes)
- ISO 6707-1 (vocabulary for buildings/civil engineering)
- ISO 9431 (drawing layout)
- ISO 23387 (data template methodology for digital construction information)
Open preview (PDF)Technical product documentation — Construction documentation — Indication of limit deviations