Swiss building rules to CAD to 3D

From a Swiss address to the rules that apply, the legal building envelope, and an Archicad-ready 3D model.

1,900+legal documents: federal, cantonal, and the regulations of 119 communes
18,000+pages of communal regulations read in a first pass
729federal and cantonal rules consolidated so far, each with its source
<1minfrom an address to an IFC file that opens in Archicad

86 seconds from the concept demo, with sound: parcel and rules, the generated model opened in Archicad, and the interior step. Narration, interface and captions are in French, the client's language.

Problem

Before architects in Switzerland can draw a line, they have to work out what may be built on the plot. That answer is spread over four layers of rules:

Layer	Volume	Covers
Federal	58 documents	Planning, environment, natural hazards, heritage, energy, accessibility, safety
Canton (Fribourg)	226 documents	Building law, definitions, fire protection, procedures
Commune	1,600+ documents, 18,000+ pages, 119 communes	Local building regulations, in French or German
Zone	Per plot	Zoning maps, overlays, special prescriptions

Volume is only half of it:

The texts are entangled. A communal rule points to a cantonal definition, which applies a federal law. No layer can be read on its own.
They have to be cross-checked. A regulation only counts once it is approved and in force, so every value is checked against approvals, amendments and the layers above it.
They keep changing. Documents are revised and replaced, so each one has to be tracked by version, and an update must never silently overwrite what was valid before.

After that comes more manual work: typing terrain heights into the CAD program and drawing every wall by hand.

What the system does

Input: an address and a rough project brief (use, size, a few design choices).

Step	Output
1. Find the plot	Boundary, area and zone from public geodata
2. Apply the rules	Density, heights, distances, legal building envelope
3. Build the site	Terrain with contour lines and point cloud
4. Generate the model	IFC file for Archicad with walls, slabs and openings
5. Interior	3D scene and a rendered proposal

Screen with an aerial map of the parcel, key figures such as area and maximum height, and a table of the applied rules with article numbers and quotes — The parcel, the numbers that apply, and the rule behind each number with its article and quote.

The generated house on its terrain in Archicad, with walls and windows as selectable elements — The generated file in Archicad: terrain, storeys, walls and windows are editable elements, not a dead mesh.

Interior module: the generated house seen from above with a furnished living room and kitchen — Interior step: the same generated model, furnished from the client's reference images. The architecture stays fixed; materials, furniture and light change.

How I keep it trustworthy

A wrong number here means a building that cannot be approved, so the system is built to show its sources and admit doubt.

Every value is traceable. A rule is stored with the document, the article and the quoted sentence. Source files are kept by hash, so a changed regulation cannot silently replace an old one.
Machine-checked is not expert-approved. A second LLM pass re-reads each extraction, and the two states are kept apart. Nothing is labelled as approved by an expert until one has looked at it.
“Needs review” is a valid answer. Several zones on one plot, conflicting texts, or special prescriptions return a review flag instead of a confident guess.
It is a first assessment, not a permit decision, and the interface says so.

Status

In progress, as a working prototype for an architecture office in the canton of Fribourg. Commune regulations with full numeric rules cover 7 communes so far; the federal and cantonal layers are consolidated into one rule base (729 rules today), and a first reading pass over the regulations of all 119 communes of the canton is done and being checked. Next: connecting communal and zone values across more communes, and validation with the architects.

My role

I design and build the whole system: the rule extraction pipeline and its data model, the geodata and terrain processing, the IFC generation, the interior module, and the web application that ties them together.