Element Catalog

Every element has a typed, validated spec in millimeters. Parametric physical elements build analytical brepjs solids in local coordinates; civil spatial elements are body-less, and Earthworks Fill accepts an arbitrary validated body. Placement is applied downstream via IfcLocalPlacement.

Element	Method	Notes
Wall	addWall	Length along axisX, openings cut via addDoor / addWindow
Slab	addSlab	FLOOR / ROOF / LANDING / BASESLAB; slab openings via parseSlabOpeningInput
Beam	addBeam	Profile extruded along axisX by length
Column	addColumn	Profile extruded along axisZ by height
Roof	addRoof	Flat slab, or shaped (shed / gable / hip / dome) when pitch is present
Curtain wall	addCurtainWall	Panel and mullion grid
Space	addSpace	Room volumes for zoning and COBie
Footing / pile	addFooting / addPile	Foundations
Stair	addStair	One or more flights, each a stepped sawtooth solid with its own placement
Ramp	addRamp	Flights like stairs, inclined slabs
Railing	addRailing	Posts + rails with infill: 'POSTED', or a single swept panel
Covering	addCovering	Finishes: flooring, cladding, ceilings
Bridge	addBridge	IFC4X3 spatial facility; no independent Body
Bridge part	addBridgePart	IFC4X3 recursive spatial part with mandatory usage type
Earthworks fill	addEarthworksFill	IFC4X3 typed arbitrary Product Body, material, and spatial containment
Proxy	addProxy	Anything else, carrying arbitrary brepjs geometry

Doors and windows are not free-standing: addDoor / addWindow take a host wall, cut the opening as a boolean void, and wire IfcRelVoidsElement + IfcRelFillsElement.

Profiles

Beams and columns extrude a profile, one vocabulary shared by both:

• Core: RECTANGULAR, CIRCULAR, I_BEAM (with optional root filletRadius)
• Extended: L / T / U / Z / C shapes, asymmetric I, ellipse, trapezium, hollow rectangular and circular sections, and arbitrary polygons with voids

Every named profile emits its own parametric IFC profile def, extended kinds included: IfcRectangleProfileDef / IfcCircleProfileDef / IfcIShapeProfileDef for the core three, and IfcLShapeProfileDef, IfcTShapeProfileDef, IfcUShapeProfileDef, IfcZShapeProfileDef, IfcCShapeProfileDef, IfcAsymmetricIShapeProfileDef, IfcEllipseProfileDef, IfcTrapeziumProfileDef, IfcRectangleHollowProfileDef and IfcCircleHollowProfileDef for the rest. The section stays editable parametric data in the exported file rather than a baked outline.

Only the two point-list kinds serialize as outlines, which is inherent to what they are: ARBITRARY_CLOSED becomes IfcArbitraryClosedProfileDef and ARBITRARY_WITH_VOIDS becomes IfcArbitraryProfileDefWithVoids.

On the brepjs side, extendedProfileToFace builds the section face for the solid and extendedProfileArea gives closed-form areas for takeoff.

Shaped roofs

pitch opts a roof into shaped geometry for its predefinedType: a right-trapezoid prism (shed), a house-pentagon prism (gable), a convex-hull hip with the ridge along the longer side, or a faceted dome. Without pitch the roof is a flat slab whatever the type says. Shaped roofs serialize as tessellated bodies; flat roofs retain IfcExtrudedAreaSolid. Every retained Wall/Railing Body item also serializes independently as a tessellated representation, regardless of authority or item count.

Placement and display

Element geometry is unplaced template geometry. origin / axisX / axisZ live in the spec and become IfcLocalPlacement. Wall and railing .geometry is a ProductBody whose kind is PARAMETRIC or AUTHORITATIVE. Both authorities hold a nonempty, ordered solids collection. bodySolids() borrows Product-local handles; do not dispose them.

Use model.replaceProductBody({ localId, body: { kind: 'AUTHORITATIVE', solids } }) to install the complete Body atomically. An error transfers nothing and leaves model state unchanged. Success returns a COMMITTED receipt and transfers all supplied solids to the model. Inspect its cleanup report separately: a failed release of the old Body does not undo the commit or return ownership of the new Body. Do not retry uncertain releases. An authoritative Body cannot revert to parametric authority.

Register wall openings before installing an authoritative Body. Later addDoor() and addWindow() calls return AUTHORITATIVE_WALL_BODY_IMMUTABLE. Existing opening relationships survive replacement, and the retained Body must already contain their geometry.

Retained Wall apertures export as IFC Reference geometry with void and fill relationships. IfcOpenShell 0.8.5 still subtracts Reference openings by default, even with a separate Reference context. If a replacement Body adds material inside a retained opening, readers using that engine can remove the added material.

familiesToBim() performs that sequence for civil-semantic walls and railings using bodyEvaluator (or proxyEvaluator). Those routes require an evaluator: missing it returns FAMILIES_PRODUCT_BODY_EVALUATOR_REQUIRED. The adapter copies every authored item into Product-local coordinates and always retains AUTHORITATIVE authority, even when the authored Body coincides with a recipe. Conventional archetype routes retain their existing recipe authoring behavior.

placedSolids(element) returns fresh, caller-owned solids transformed by the element's own placement. For an element beneath a placed spatial structure, pass its cumulative frame as placedSolids(element, { parentFrame }) to obtain world coordinates. Both Product Body authorities return one placed copy per item. Stairs and ramps return one per flight, and curtain walls return their panels and mullions. Geometry-free elements return an empty list. Dispose every returned solid.

Wall net volume measures the occupied union of all Body items. Length, Width, and Height remain nominal dimensions from the Wall spec. After Body replacement, those dimensions do not establish gross volume, surface quantities, or weight. Recipe-derived quantities require current model recipe eligibility; replacing a Body clears that eligibility even if the replacement is tagged PARAMETRIC. Measurement failures omit the affected quantities and produce WALL_QUANTITY_OMITTED issues from toIfcValidated().

Other categories retain class-specific storage in step 1. Converging that storage and removing the transitional model ownership enumerator are step-2 work.

Data layers

Beyond geometry, elements carry: property sets from IFC pset templates with typed measures, quantity sets for takeoff, materials (simple, layer sets, profile sets), classification references (Uniclass, OmniClass, and friends), surface styles, and zone / system membership. Stable identity comes from deterministic GUIDs: deriveIfcGuid for content-derived ids, newIfcGuid for random ones.