Build a Complete BIM Model in 3–6 Hours

Introduction

What you will build

By following this guide, you'll produce a complete BIM model comparable to what a junior architect would build in 3–6 hours — including the design decisions, constraints, schedules, and design book sheets. No reverse-engineering required.

This guide uses the Office Building template as the reference project (5-story, 40×25m footprint, curtain wall facade). The same workflow applies to all three template typologies.

Prerequisites

• Browser-based — no install required
• Basic BIM knowledge (what a wall, column, level means)
• No Atlantist-specific training needed

Step 1

Levels & Elevations

Levels are the binding reference for every other element. Change a level elevation → the DAG recalculates all hosted elements. Spend time getting this right upfront.

How to add a level

Level bindings explained

Step 2

Walls

Walls are placed by defining two XY coordinates in the plan view. Each wall type has a multi-layer construction — changing the type propagates through all instances via the DAG.

How to place a wall

Wall layer system

Every wall is built from ordered layers. The layer system drives the wall assembly in the design book output (finish schedule):

Wall parameter reference

Step 3

Floors & Roofs

Floors are horizontal elements bound to a base_level_id. They have multi-layer construction (structure/finish/insulation). Roofs are flat floors at the top level.

Floor type catalog

How to add a floor

In the 3D View, click + Floor in the toolbar. The floor inherits its elevation from the base_level_id. The boundary polygon is drawn in plan view.

Roof types

Roofs use the same floor system but are marked as the top level (no top_level_id binding). Curved roof surfaces (barrel vault, hip, gambrel) are created using the Curved Surfaces primitive system (Phase 22).

Adding a curved roof

1. Click + Curved in the toolbar
2. Select surface type: Barrel Vault, Hip, Gambrel, Hyperboloid, etc.
3. Set the base elevation and profile parameters (rise, span, radius)
4. The roof mesh is generated parametrically — change the rise, the roof updates
5. IFC export: revolution surfaces become IfcBuildingElementProxy, NURBS become IfcBSplineSurfaceWithKnots

Step 4

Doors & Windows

Doors and windows are family instances hosted on wall faces. Placement auto-cuts wall geometry to match the family dimensions — no manual cutting required.

How to place a door

Door type catalog

Window type catalog

Auto-cut geometry

When you place a door or window, the wall's parameters.cutOpenings JSON records the opening dimensions. The Three.js mesh builder subtracts this geometry from the wall mesh, leaving a clean rectangular void with a frame.

Step 5

Stairs & Railings

Stairs are parametric elements — you set base/top levels and the DAG computes riser height, tread depth, and total run. All values are IBC 1011-compliant by default.

How to add a stair

Stair type catalog (IBC Table 1011.2)

Railings

Railings are created after the stair. They bind to the stair via host_stair_id and are placed on the left/right side. IBC requires 42" guards on open sides, 34"–38" handrails.

Railing type catalog

Step 6

Structural Members

Columns are placed at grid intersections. Beams run between columns. Both are bound to levels — changing a level height updates all connected structural members.

Column types

Structural grids

The grid system places columns at defined spacing. For the office template, the grid is 8m × 5m. Columns are bound to the grid intersection coordinates — move a grid line and all columns update.

Beam types (AISC W-shapes)

Step 7

MEP Stubs

Place MEP fixture stubs (VAV boxes, diffusers, sprinkler heads, electrical panels) to enable HVAC, plumbing, and electrical simulation. Stubs are bound to levels and rooms.

MEP fixture catalog

Running HVAC simulation

After placing VAV stubs and diffusers, open MEP → HVAC Run. The simulation computes:

• Zone loads from wall geometry + level spans
• 1 zone per ~1500m² of floor area
• CFM from cooling Btu/h (1 ton = 12000 Btu/h, 400 CFM/ton)
• Duct sizing from zone peak CFM
• Airflow particles for visualization

Step 8

Energy Zones & Simulation

Rooms become energy zones. Assign room boundary polygons and run a simulation to generate gbXML + EN-001 to EN-008 compliance output.

How to set up energy simulation

Step 9

Design Book Output

The design book auto-generates sheets from model data. No manual annotation required post-modeling.

What auto-populates

• Floor Plans — from element geometry + structural grid
• Elevations — N↑ S↑ E→ W← orthographic views (A-200 / A-201 / A-202 / A-203)
• Door Schedule (A-400) — from family_instance parametric data: mark, type, width, height, fire rating, material
• Window Schedule (A-400) — from family_instance: mark, type, width, height, sill height, glazing
• Room Schedule — from rooms table: number, name, area_sqm, floor/ceiling finish
• Finish Schedule — from wall_layers: material, function, thickness
• Material Takeoff — aggregate wall layer volumes
• Section Cuts — draw section lines on plan → elevation view auto-generates

Creating section cuts

1. Click Section in the toolbar
2. Click two points on the plan view to define the cut plane
3. The section camera moves perpendicular to the line, showing the elevation at that cut
4. Use elevation buttons (N↑ S↑ E→ W←) to switch to fixed orthographic views
5. Export any sheet as PDF or CSV

Step 10

Parametric Constraints & DAG

The DAG (Directed Acyclic Graph) constraint solver propagates every parameter change instantly across all bound elements. This is what makes Atlantist parametric — not just a 3D viewer.

Constraint chain example

Event Ledger (audit trail)

Every parameter change is recorded in the event_ledger with: actor, timestamp, before/after values. This enables per-element revert: open the History panel, find the event, click Revert. A new shadow page event is written and the scene reloads for all collaborators.

Group rotation

Select multiple elements (Ctrl+click) and press Space or click ↻ Rotate 45°. All selected elements rotate 45° CW around the selection barycenter in a single atomic undo. Live sync to collaborators via WebSocket.

Step 11

Export (IFC / DWG)

Atlantist exports industry-standard BIM formats that open in Revit, ArchiCAD, and other tools.

IFC Export (IFC 2x3)

Click IFC Export in the toolbar. The exporter generates a valid IFC 2x3 STEP file with:

• IfcWallStandardCase with ExtrudedAreaSolid geometry
• IfcColumn with structural section profile
• IfcDoor and IfcWindow with hosted opening geometry
• IfcBuildingStorey (levels) as IfcBuildingElementDecomposition
• IfcBSplineSurfaceWithKnots for NURBS curved surfaces
• IfcBuildingElementProxy for revolution/sweep surfaces

IFC Import

Click IFC Import → drag-and-drop a STEP file. The parser extracts IfcWallStandardCase, IfcColumn, IfcDoor, IfcWindow, IfcBuildingStorey entities and maps them to Atlantist elements. Progress shown in real time.

DWG Export

Click DWG Export for AutoCAD-compatible output. Generates DXF R14/2000 text with:

• Wall polylines with layer naming (A-WALL, A-DOOR, A-WINDOW)
• Grid lines on dedicated layer (A-GRID)
• Room boundary polygons (A-AREA)
• Dimension text (A-DIMS)

Quick-Start

Template Projects

Don't start from scratch. The template projects are pre-built scaffolds — levels, walls, floors, stairs, MEP stubs, and energy zones already configured. Instantiate one and modify it.

How to use a template

1. Open Projects → click the Templates tab
2. Click a template card to preview: level count, element count, construction type, floor height
3. Enter a project name and click Use This Template
4. A new project is created — modify, extend, delete anything
5. All elements are live-parametric — no lock-in

Reference

Gotchas & Known Issues