My first Bonsai

The file is the document

Mon, 31 Aug 2026 00:00:00 +0000

Press Ctrl-S with a project open and Bonsai writes your IFC file. Not a copy of it, not an export of it, but the file itself - the one you opened, and the one you will send to somebody. That is the whole of this page. Everything else on it is a consequence.

Most BIM software keeps your work in a format of its own and treats IFC as something you produce at the end, for other people. Bonsai has no format of its own. The .ifc file is the document, in the way that a .txt file is the document when you open it in a text editor. There is nothing else to save.

Bonsai is a mod, not a panel

Mon, 31 Aug 2026 00:00:00 +0000

In Blender, G grabs whatever is selected and moves it. It is the first key anybody learns. With Bonsai enabled it is not Blender’s key any more.

Nor are X and Del, Shift-D, Alt-D, Ctrl-J, Ctrl-V, Tab, Space or Esc. Every one of them has been rebound to an operator of Bonsai’s own. These are not obscure corners of the keymap that nobody visits. They are move, delete, duplicate, join, paste and edit mode - the keys you press without deciding to.

The model is a graph of standard objects

Mon, 31 Aug 2026 00:00:00 +0000

An IFC file is a carrier bag full of everything to do with a building project. Geometry, yes, but also schedules, tasks, costs, materials, the people and organisations involved, the systems that run through the building - all of it in the one container, which you can pick up and hand to somebody.

It is a bag packed to a published standard. Every item in it is labelled, and where each kind of item goes is prescribed rather than left to whoever did the packing.

Containment - the spatial tree

Mon, 31 Aug 2026 00:00:00 +0000

Every physical thing in an IFC model is assigned to somewhere. Not usually, not by convention - as a matter of structure. A wall belongs to a storey, the storey belongs to a building, the building sits on a site, and the site belongs to the project.

IfcProject
 IfcSite
 IfcBuilding
 IfcBuildingStorey
 IfcSpace

That is the spatial tree, and an element that is not somewhere on it is not properly in your model, however solid it looks in the viewport.

Definition - types and occurrences

Mon, 31 Aug 2026 00:00:00 +0000

In an IFC file a wall type and a wall are two different objects. The type is IfcWallType; the wall standing in your building is an IfcWall, and a relationship in the file says that this wall is an occurrence of that type.

Fifty walls of the same construction are fifty occurrences pointing at one definition. Change the definition and you have changed all fifty.

What the type carries is whatever is true of the construction rather than of any particular wall - properties, and materials. The occurrence keeps what is genuinely its own: where it stands, what it is called, which storey it is on, and any properties you have attached to that one wall.

Description - properties, materials and classifications

Mon, 31 Aug 2026 00:00:00 +0000

A wall in a finished model carries a good deal more than its shape. It knows whether it is external, what it is rated to for fire and for sound, what it is made of and in what order, what its area and volume are, and what it is called in whichever classification table the job is using.

None of that is metadata hung off the side of the model. It is the model. The shape is one attribute among many, and on most days it is not the one anybody is asking about.

Representations - one object, several geometries

Mon, 31 Aug 2026 00:00:00 +0000

How many geometries does a door have? The question sounds like it has an obvious answer, and in an IFC file it does not. A door may have none, or one, or half a dozen, and a model full of doors may have a different number for each.

Each of those geometries is a representation, and the plural is the point of this page.

A representation is addressed by what it is for

Representations are not a list you index into. Each one is filed under what it is for, using three things: a context, an identifier, and a target view.

What is parametric and what is not

Mon, 31 Aug 2026 00:00:00 +0000

Select a wall in your model, press G, and drag it across the room. Its windows and doors travel with it, still in their openings, still glazed.

Now select just a window in that wall and drag it sideways. The window moves. The hole it was sitting in stays exactly where it was.

Both of those are Bonsai working correctly, and nothing on your screen told you which one you were about to get. That is what this page is for.

Finding things

Mon, 31 Aug 2026 00:00:00 +0000

Most of what is in your model cannot be clicked on. Property sets, classifications, materials, tasks, cost items - none of it has a shape in the viewport, and the parts that do have shapes are frequently buried behind other shapes.

So clicking cannot be the main way you reach the model, and if it is the only way you know, you are working with the small visible fraction of your project. This page is the practical answer to The model is a graph of standard objects.

What comes out

Mon, 31 Aug 2026 00:00:00 +0000

A drawing in Bonsai is not a file that sits next to your model. It is an object inside it.

Specifically, it is an annotation entity with a scale, a position, a direction to look in, and a note of which kind of view it is - a plan, a reflected plan, a section, an elevation. Add a drawing to your project and your .ifc file has grown by one object. Send the file to somebody and you have sent them the drawings.

Checking the model

Mon, 31 Aug 2026 00:00:00 +0000

Imagine a small IFC file. It contains a project and one wall, and the wall has no properties at all.

Ask whether it is a valid IFC file and the answer is yes, without qualification - it conforms to the standard, and a validator reports no issues. Ask whether it is an acceptable model and the answer is obviously no, because nobody wants a wall that does not know what it is rated to.

Other people's models

Mon, 31 Aug 2026 00:00:00 +0000

There is no central model.

If you have worked in Revit’s worksharing or ArchiCAD’s Teamwork, nothing here corresponds to them: no authoritative copy of the project that everybody else takes a local file from, no elements to reserve before you are allowed to edit them, and no moment at which somebody else’s work arrives in yours because a synchronise button was pressed.

To anybody trained on a system built around a shared database, that will read as a list of missing features. It is worth understanding why it is not, because the reasoning turns out to be about professional responsibility rather than about software.

Revisions

Mon, 31 Aug 2026 00:00:00 +0000

This page is not really about a feature. It is about what becomes available once the document is an ordinary file, which is the argument of The file is the document arriving at its most useful consequence.

Because an .ifc is text, the tools that the rest of the world built for keeping the history of text files work on your building model. Bonsai puts a panel over the most widely used of them, Git, but nothing conceptually new is being introduced. Your project is a file in a folder, and the folder can remember.

What else is in the box

Mon, 31 Aug 2026 00:00:00 +0000

You do not have to assemble anything. Clash detection, model checking, schedules, drawings, quantities, cost, programme, patching, version control - they are all inside the add-on you have already installed. There is no toolchain to put together before you can start, and nothing on this page is a shopping list.

You have been using the box the whole time

Bonsai is built out of some fifty-odd modules, and most of the ones that matter have already appeared in this guide. Searching and filtering, drawings and sheets, schedules and quantity take-off, clash detection, IDS checking, BCF, Git support, cost items and work programmes, patching, facility management handover.

Who makes Bonsai

Wed, 02 Sep 2026 00:00:00 +0000

Somewhere in your copy of Bonsai there is a file called FixRevit2025TINs.py.

Nobody planned that file. It was not on a roadmap and no committee approved it. Somebody was handed a survey exported from a 2025 version of Revit, found that the triangulated surfaces in it came through wrong, worked out precisely how they were wrong, and wrote a short Python recipe to put them right. That recipe shipped. It is on your machine now, waiting for the day somebody hands you the same file.

About this guide

Mon, 31 Aug 2026 00:00:00 +0000

This guide is for architects and other building professionals who are moving to Bonsai, particularly those arriving from Revit or ArchiCAD, and it tries to answer one question that the existing documentation does not: what kind of thing is this?

The official documentation is task-shaped, and good at what it does - install this, click here, make a wall. What it assumes is that you already understand the arrangement you have stepped into: that the file is the project, that the model is a graph of standard objects, that drawings come out of the model rather than sitting beside it. Somebody arriving from a system built on quite different assumptions has to reconstruct all of that from the tasks, and most people give up somewhere in the middle.