Filter or require elements based on classification system references. Classifications like Uniclass, OmniClass, and others provide standardized ways to categorize building elements.

Parameters

Using in IDSedit

As Applicability

Filter elements by their classification:

1. Add a Classification Facet to the Applicability section
2. Enter the classification System name
3. Optionally specify a Value (classification code)

Example: Target elements classified as external walls in Uniclass by setting System to Uniclass 2015 and Value to EF_25_10_25

As Requirement

Require elements to have a classification:

1. Add a Classification Facet to the Requirements section
2. Specify the required classification system
3. Optionally require a specific code or code pattern

Major Classification Systems

Uniclass 2015 (UK)

The UK standard for construction classification:

Pattern example: EF_25.* matches all Uniclass wall elements

OmniClass (North America)

US/Canadian construction classification:

CCI (Nordic)

Construction Classification International:

NL-SfB (Netherlands)

Dutch construction classification based on SfB:

Custom Systems

You can use any classification system name. Common patterns:

• Company-specific systems: ACME Classification
• Project-specific systems: Project XYZ Categories

Value Patterns

Exact Match

System: Uniclass 2015
Value: EF_25_10_25

Hierarchical Matching

Match all codes in a branch using patterns:

Multiple Values

Use enumeration restrictions to allow several codes:

System: Uniclass 2015
Value: ["EF_25_10_25", "EF_25_10_30", "EF_25_10_35"]

Common Use Cases

Require Classification

Ensure all elements are classified:

System: Uniclass 2015
Value: (empty - any code accepted)

Discipline-Specific Classification

Target structural elements:

System: Uniclass 2015
Value: Pattern "Ss_25.*" (structural systems)

Product Specifications

Require product-level classification:

System: Uniclass 2015
Value: Pattern "Pr_.*" (any product code)

Cost Code Assignment

For cost estimation workflows:

System: Cost Codes
Value: Pattern "[0-9]{4}" (4-digit cost code)

Multiple System Support

Elements can have multiple classifications. You can require multiple systems:

• Specification 1: Uniclass 2015 classification
• Specification 2: OmniClass classification

How Classifications Work in IFC

Classifications are attached to elements via IfcRelAssociatesClassification:

Element (IfcWall)
  └── IfcRelAssociatesClassification
        └── IfcClassificationReference
              ├── Identification: "EF_25_10_25"
              └── ReferencedSource
                    └── IfcClassification
                          └── Name: "Uniclass 2015"

The Classification Facet checks this entire chain to match your criteria.

Technical Notes

• System names are matched case-insensitively
• Classification values/codes are matched case-sensitively by default
• Elements can have multiple classifications from different systems
• Classification can be applied to instances or types (or both)
• Empty Value means "must have any classification in this system"

Classification Resources

Official Sources

• Uniclass 2015 - NBS maintained
• OmniClass - CSI maintained
• buildingSMART Data Dictionary - Classification URIs

IFC Documentation

• IfcClassification
• IfcClassificationReference

Learn More

For detailed specification information, see the official Classification Facet documentation from buildingSMART.