bonsai-agents-ifc-validator

Bonsai IFC Validator Agent

Version: Bonsai v0.8.x | IfcOpenShell v0.8+ | Blender 4.2.0+ | Python 3.11 IFC Schemas: IFC2X3, IFC4, IFC4X3 Dependencies: bonsai-core-architecture, bonsai-syntax-properties, ifcos-impl-validation

Quick Reference: When to Activate

Activate this validator when the user:

Requests validation, auditing, checking, or verification of an IFC model
Asks to run quality assurance (QA) on a Bonsai project
Needs to verify IFC compliance before model handover or delivery
Wants to check an IFC model against an IDS specification
Asks to diagnose structural or data issues in an IFC file
Requests a pre-submission or pre-export quality check
Needs to verify spatial hierarchy, property completeness, or classification correctness

Critical Warnings

ALWAYS run validation in the prescribed order: Schema → Spatial → Properties → Geometry → Classification → IDS. Schema failures invalidate all subsequent checks.
ALWAYS check model.schema before applying version-specific validation logic. IFC2X3, IFC4, and IFC4X3 have different entity sets and rules.
NEVER assume a model is valid because ifcopenshell.validate.validate() completes without exception. Validation issues are logged, NOT raised. Use json_logger or LogDetectionHandler to detect issues.
ALWAYS use ifcopenshell.util.element.get_psets() for property reading. NEVER traverse IsDefinedBy relationships manually.
ALWAYS use ifctester for IDS validation. ifcopenshell.validate checks schema compliance only — it does NOT check project-specific requirements.
NEVER confuse schema validation with IDS validation. Schema validation verifies IFC file structure per EXPRESS schema. IDS validation verifies IFC data meets project information requirements.
ALWAYS access the IFC model via tool.Ifc.get() inside Bonsai or IfcStore.get_file(). NEVER access IfcStore.file directly.
ALWAYS guard against None return from IfcStore.get_file() before running any validation.

Validation Process: Execution Order

Execute these phases sequentially. If Phase 1 (Schema) produces BLOCKER-level issues, STOP and report before continuing.

Phase 1: Schema Validation

Validates IFC file structure against the EXPRESS schema definition.

import ifcopenshell
import ifcopenshell.validate

model = ifcopenshell.open("project.ifc")  # or tool.Ifc.get() inside Bonsai

# Step 1: Basic schema validation
json_log = ifcopenshell.validate.json_logger()
ifcopenshell.validate.validate(model, json_log)

schema_errors = [s for s in json_log.statements if s["level"] == "ERROR"]
schema_warnings = [s for s in json_log.statements if s["level"] == "WARNING"]

# Step 2: If basic passes, run EXPRESS WHERE rules (10-100x slower)
if not schema_errors:
    json_log_express = ifcopenshell.validate.json_logger()
    ifcopenshell.validate.validate(model, json_log_express, express_rules=True)

Severity mapping:

Condition	Severity
Any ERROR in json_log.statements	BLOCKER
Any WARNING in json_log.statements	WARNING
EXPRESS WHERE rule violation	WARNING
Clean schema validation pass	INFO (proceed)

Phase 2: Spatial Hierarchy Validation

Verifies the required IFC spatial structure exists and all elements are contained.

import ifcopenshell
import ifcopenshell.util.element

def validate_spatial_hierarchy(model):
    errors = []
    schema = model.schema

    # 2a: Verify IfcProject exists (exactly one)
    projects = model.by_type("IfcProject")
    if len(projects) != 1:
        errors.append(("BLOCKER", f"Expected 1 IfcProject, found {len(projects)}"))
        return errors

    # 2b: Verify IfcSite exists
    sites = model.by_type("IfcSite")
    if len(sites) == 0:
        errors.append(("BLOCKER", "No IfcSite found"))

    # 2c: Verify IfcBuilding exists
    buildings = model.by_type("IfcBuilding")
    if len(buildings) == 0:
        errors.append(("BLOCKER", "No IfcBuilding found"))

    # 2d: Verify IfcBuildingStorey exists (standard buildings)
    storeys = model.by_type("IfcBuildingStorey")
    if len(storeys) == 0 and len(buildings) > 0:
        errors.append(("WARNING", "No IfcBuildingStorey found"))

    # 2e: Verify spatial decomposition chain
    # IFC4X3 allows IfcFacility / IfcFacilityPart as alternatives
    if schema == "IFC4X3":
        facilities = model.by_type("IfcFacility")
        if len(buildings) == 0 and len(facilities) == 0:
            errors.append(("BLOCKER", "No IfcBuilding or IfcFacility found"))

    # 2f: Check all physical elements have spatial containment
    for element in model.by_type("IfcElement"):
        container = ifcopenshell.util.element.get_container(element)
        if container is None:
            errors.append((
                "WARNING",
                f"#{element.id()} {element.is_a()} '{element.Name}': "
                f"Not contained in any spatial element"
            ))

    return errors

Severity mapping:

Condition	Severity
Missing IfcProject or count != 1	BLOCKER
Missing IfcSite	BLOCKER
Missing IfcBuilding (IFC2X3/IFC4)	BLOCKER
Missing IfcBuilding AND IfcFacility (IFC4X3)	BLOCKER
Missing IfcBuildingStorey	WARNING
IfcElement without spatial containment	WARNING
Spatial hierarchy complete	INFO

Phase 3: Property Set Compliance

Validates property sets exist and contain required properties.

import ifcopenshell.util.element

def validate_property_compliance(model, requirements):
    """
    requirements: dict of {ifc_class: {pset_name: [prop_names]}}
    Example: {"IfcWall": {"Pset_WallCommon": ["IsExternal", "FireRating"]}}
    """
    errors = []
    for ifc_class, pset_reqs in requirements.items():
        elements = model.by_type(ifc_class)
        for element in elements:
            psets = ifcopenshell.util.element.get_psets(element)
            for pset_name, required_props in pset_reqs.items():
                if pset_name not in psets:
                    errors.append((
                        "WARNING",
                        f"#{element.id()} {element.is_a()} '{element.Name}': "
                        f"Missing pset '{pset_name}'"
                    ))
                    continue
                for prop in required_props:
                    val = psets[pset_name].get(prop)
                    if val is None:
                        errors.append((
                            "WARNING",
                            f"#{element.id()} {element.Name}: "
                            f"Missing {pset_name}.{prop}"
                        ))
    return errors

Standard property requirements by element type:

IFC Class	Standard Pset	Key Properties
`IfcWall`	`Pset_WallCommon`	IsExternal, LoadBearing, FireRating
`IfcSlab`	`Pset_SlabCommon`	IsExternal, LoadBearing
`IfcDoor`	`Pset_DoorCommon`	IsExternal, FireRating
`IfcWindow`	`Pset_WindowCommon`	IsExternal, ThermalTransmittance
`IfcBeam`	`Pset_BeamCommon`	LoadBearing
`IfcColumn`	`Pset_ColumnCommon`	LoadBearing
`IfcSpace`	`Pset_SpaceCommon`	IsExternal, GrossPlannedArea

Severity mapping:

Condition	Severity
Standard pset completely missing on element	WARNING
Required property missing from existing pset	WARNING
Property value is empty/null	INFO
All required properties present	INFO

Phase 4: Geometry Validation

Checks geometry representations exist and are valid.

def validate_geometry(model):
    errors = []

    for element in model.by_type("IfcElement"):
        # 4a: Check element has a representation
        if not element.Representation:
            errors.append((
                "WARNING",
                f"#{element.id()} {element.is_a()} '{element.Name}': "
                f"No geometry representation"
            ))
            continue

        # 4b: Check representation has items
        for rep in element.Representation.Representations:
            if not rep.Items or len(rep.Items) == 0:
                errors.append((
                    "WARNING",
                    f"#{element.id()} {element.Name}: "
                    f"Empty representation '{rep.RepresentationIdentifier}'"
                ))

    # 4c: Check for placement consistency
    for element in model.by_type("IfcElement"):
        if element.ObjectPlacement is None:
            errors.append((
                "INFO",
                f"#{element.id()} {element.is_a()} '{element.Name}': "
                f"No IfcLocalPlacement"
            ))

    return errors

Severity mapping:

Condition	Severity
IfcElement with no Representation at all	WARNING
Empty representation (no Items)	WARNING
Missing IfcLocalPlacement	INFO
Valid geometry present	INFO

Phase 5: Classification Validation

Verifies classification references (Uniclass, OmniClass, NL-SfB, etc.) are present and correctly structured.

import ifcopenshell.util.classification

def validate_classifications(model, required_system=None):
    errors = []

    # 5a: Check classification systems exist
    systems = model.by_type("IfcClassification")
    if len(systems) == 0:
        errors.append(("INFO", "No classification system referenced in model"))
        return errors

    if required_system:
        system_names = [s.Name for s in systems]
        if required_system not in system_names:
            errors.append((
                "WARNING",
                f"Required classification system '{required_system}' not found. "
                f"Available: {system_names}"
            ))

    # 5b: Check elements have classification references
    classified_count = 0
    unclassified = []
    for element in model.by_type("IfcElement"):
        refs = ifcopenshell.util.classification.get_references(element)
        if refs:
            classified_count += 1
        else:
            unclassified.append(element)

    total = len(model.by_type("IfcElement"))
    if unclassified:
        errors.append((
            "INFO",
            f"{len(unclassified)}/{total} elements lack classification references"
        ))

    # 5c: Validate classification reference format
    for ref in model.by_type("IfcClassificationReference"):
        if not ref.Identification and not ref.ItemReference:
            errors.append((
                "WARNING",
                f"#{ref.id()} IfcClassificationReference: "
                f"Missing Identification/ItemReference"
            ))

    return errors

Severity mapping:

Condition	Severity
No classification system in model	INFO
Required classification system missing	WARNING
Element lacks classification reference	INFO
IfcClassificationReference with empty ID	WARNING

Phase 6: IDS Validation (Information Delivery Specification)

Validates the IFC model against an IDS specification file using ifctester.

import ifctester
import ifctester.ids
import ifctester.reporter

def validate_ids(model, ids_path):
    """Validate model against IDS specification."""
    errors = []

    # 6a: Load IDS specification
    ids = ifctester.open(ids_path)

    # 6b: Run validation
    ids.validate(model)

    # 6c: Collect results per specification
    for spec in ids.specifications:
        total = spec.total_applicable
        passed = spec.total_pass
        failed = spec.total_fail

        if failed > 0:
            severity = "BLOCKER" if spec.minOccurs > 0 else "WARNING"
            errors.append((
                severity,
                f"IDS '{spec.name}': {failed}/{total} elements failed"
            ))

    # 6d: Generate report
    reporter = ifctester.reporter.Json(ids)
    reporter.report()
    report_data = reporter.to_string()

    return errors, report_data

Bonsai UI access: BIM > IFC Tester panel provides integrated IDS validation.

Severity mapping:

Condition	Severity
Required IDS specification failed	BLOCKER
Optional IDS specification failed	WARNING
All IDS specifications passed	INFO
No IDS specification provided	INFO (skip phase)

Decision Tree: Validation Severity Classification

Issue found during validation
|
+--> Does it violate IFC schema rules?
|    +--> YES --> BLOCKER (invalid IFC file, model cannot be trusted)
|    +--> NO --> continue
|
+--> Does it break spatial hierarchy completeness?
|    +--> Missing IfcProject/IfcSite/IfcBuilding? --> BLOCKER
|    +--> Missing IfcBuildingStorey? --> WARNING
|    +--> Element not spatially contained? --> WARNING
|    +--> NO --> continue
|
+--> Does it fail a required IDS specification?
|    +--> YES (minOccurs > 0) --> BLOCKER
|    +--> YES (optional) --> WARNING
|    +--> NO --> continue
|
+--> Does it involve missing required properties?
|    +--> Missing standard pset entirely? --> WARNING
|    +--> Missing individual property? --> WARNING
|    +--> Empty property value? --> INFO
|    +--> NO --> continue
|
+--> Does it involve geometry issues?
|    +--> No representation at all? --> WARNING
|    +--> Empty representation? --> WARNING
|    +--> Missing placement? --> INFO
|    +--> NO --> continue
|
+--> Does it involve classification?
     +--> Required system missing? --> WARNING
     +--> Element unclassified? --> INFO
     +--> Malformed reference? --> WARNING

Severity Definitions:

Severity	Meaning	Action
BLOCKER	Model is invalid or non-compliant. Delivery MUST NOT proceed.	Fix immediately. Re-validate after fix.
WARNING	Data quality issue. Model is technically valid but incomplete.	Fix before delivery if requirements demand it.
INFO	Observation. No action required unless project rules specify otherwise.	Document for awareness.

IDS Integration: ifctester Usage Patterns

Core Workflow

import ifctester
import ifctester.ids
import ifctester.reporter
import ifcopenshell

# Load IDS and IFC
ids = ifctester.open("specification.ids")
model = ifcopenshell.open("project.ifc")

# Validate and report
ids.validate(model)
ifctester.reporter.Console(ids).report()

Report Formats

Format	Reporter Class	Use Case
Console	`ifctester.reporter.Console(ids)`	Quick interactive checks
JSON	`ifctester.reporter.Json(ids)`	CI/CD pipelines
HTML	`ifctester.reporter.Html(ids)`	Stakeholder reports
BCF	`ifctester.reporter.Bcf(ids)`	BIM coordination
ODS	`ifctester.reporter.Ods(ids)`	Spreadsheet review

IDS Facet Types

Facet	Checks
Entity	IFC class and predefined type
Attribute	Entity attribute values
Classification	Classification references present
Property	Property set values
Material	Material assignments
PartOf	Spatial/aggregation relationships

Model Access

Context	Access Method
Inside Bonsai	`model = tool.Ifc.get()` — ALWAYS check for None
Inside Bonsai (legacy)	`model = IfcStore.get_file()`
Standalone/headless	`model = ifcopenshell.open("project.ifc")`
Bonsai UI IDS	`BIM > IFC Tester` panel

Version-Specific Validation Notes

Aspect	IFC2X3	IFC4	IFC4X3
Spatial root	IfcProject → IfcSite → IfcBuilding	Same as IFC2X3	IfcProject → IfcSite → IfcBuilding OR IfcFacility
Georeferencing	Property sets on IfcProject	IfcMapConversion + IfcProjectedCRS entities	Same as IFC4 + IfcMapConversionScaled
Classification	IfcClassificationReference.ItemReference	IfcClassificationReference.Identification	Same as IFC4
Property templates	Limited	Full IfcPropertySetTemplate support	Full support
IDS support	Yes (via ifctester)	Yes (via ifctester)	Yes (via ifctester)

References

Validation Methods — Validation rules, ifctester API, and function signatures
Validation Examples — Complete validation workflow examples
Anti-Patterns — Common validation mistakes and how to avoid them

Dependencies

bonsai-core-architecture — IfcStore access, tool.Ifc, three-layer architecture
bonsai-syntax-properties — Property set reading and validation patterns
ifcos-impl-validation — ifcopenshell.validate, ifctester, georeference validation

Sources

Bonsai Documentation: https://docs.bonsaibim.org
IfcOpenShell Validation: https://docs.ifcopenshell.org
buildingSMART IDS: https://technical.buildingsmart.org/projects/information-delivery-specification-ids/
IFC Schema Specifications: https://standards.buildingsmart.org/IFC/

About this skill

Quick Reference: When to Activate

Critical Warnings

Validation Process: Execution Order

Phase 1: Schema Validation

Phase 2: Spatial Hierarchy Validation

Phase 3: Property Set Compliance

Phase 4: Geometry Validation

Phase 5: Classification Validation

Phase 6: IDS Validation (Information Delivery Specification)

Decision Tree: Validation Severity Classification

IDS Integration: ifctester Usage Patterns

Core Workflow

Report Formats

IDS Facet Types

Model Access

Version-Specific Validation Notes

References

Dependencies

Sources