What Is the Arch Workbench in FreeCAD?
The Arch workbench in FreeCAD provides modern Building Information Modeling (BIM) capabilities within an open-source parametric modeler. It allows architects, engineers, and designers to create parametric architectural components such as walls, roofs, windows, and structural frames, while facilitating the export of standard 2D documentation and industry-standard IFC files. This article explains the primary purpose of the Arch workbench, its core features, and how it functions within architectural workflows.
Purpose of the Arch Workbench
The primary purpose of the Arch workbench is to transition FreeCAD from a general-purpose mechanical CAD program into a dedicated architectural design and BIM application. Traditional CAD software relies on generic solids and meshes, whereas the Arch workbench treats components as functional building objects containing architectural properties, material attributes, and volumetric data.
Key Features and Capabilities
1. Parametric Architectural Components
The Arch workbench enables users to generate standard building elements dynamically. These components remain fully parametric, meaning dimensions, alignments, and parameters can be adjusted at any stage of the design process:
- Walls and Structures: Generate solid walls from 2D lines or sketches, as well as structural members like columns, beams, and foundations.
- Windows and Doors: Insert parametric openings that automatically cut voids into host walls.
- Roofs and Stairs: Build complex roof pitches, hips, and customizable staircases with automatic tread and riser calculations.
- Panels and Equipment: Model interior fixtures, curtain walls, and custom furniture assemblies.
2. OpenBIM and IFC Interoperability
A central function of the Arch workbench is its native integration
with the Industry Foundation Classes (IFC) data model. Users can assign
standard IFC classifications (such as IfcWall,
IfcWindow, or IfcBeam) to components. This
enables bidirectional collaboration with commercial BIM platforms like
Autodesk Revit and Graphisoft Archicad without vendor lock-in.
3. 2D Drafting and Document Generation
The workbench bridges 3D models and 2D construction documentation. By utilizing Arch Section Planes in combination with FreeCAD’s TechDraw workbench, users can extract dynamic floor plans, elevations, and cross-sections. When the 3D model changes, the linked 2D projection views and dimensioned drawings update automatically.
4. Material Data and Quantity Takeoffs
Beyond geometry, the Arch workbench allows the assignment of materials and multi-layered material configurations (such as insulation layers within external walls). This structured data enables accurate material schedules, volume calculations, and area takeoffs directly from the model.
Evolution into the BIM Workbench
In FreeCAD version 0.21 and the milestone 1.0 release, the Arch workbench and the Draft-based BIM tools were unified into a comprehensive, dedicated BIM workbench. The foundational tools, commands, and IFC workflow pioneered by the Arch workbench remain the core engine driving all architectural modeling inside FreeCAD today.