What is BIM?
Updated · BIMViewer team
BIM — Building Information Modeling — is the practice of designing, building and operating a construction project around a shared digital model instead of a pile of drawings. The model is not a picture of the building; it is a database shaped like the building. Every wall, beam, duct and door in it is an object that knows its own type, its position, its relationships ("this door is hosted by that wall") and its data — fire ratings, areas, materials, manufacturer references.
That one shift — from drawings that humans interpret to objects that software can query — is what everything else in BIM hangs off. Quantities can be extracted instead of measured off sheets. Conflicts between disciplines can be found in the model instead of on site. A facilities team can inherit a structured asset register instead of a box of PDFs.
If a BIM model has just landed in your inbox and you want to see it rather than read about it: drop the file into the free browser viewer. It runs entirely on your machine — the model is never uploaded — and the rest of this guide will make more sense with a real building on screen.
What's actually in a building information model
Strip away the acronyms and a BIM model carries four kinds of content:
Objects with identity. Elements are typed — a column is an
IfcColumn, a pump an IfcPump — and each carries a GlobalId, a
unique fingerprint that lets tools track the same element across model versions and clash
reports. When a coordinator says "element 2O2Fr…", every tool on the project can find it.
Geometry with placement. Shapes live in a spatial hierarchy — site, building, storey, element — so software can isolate level 3 or hide everything except the sprinkler system without anyone drawing those views in advance.
Properties and quantities. Structured data hangs off every element in named groups (property sets and quantity sets). This is where the load-bearing flags, the U-values, the net areas and volumes live — the raw material of cost plans, energy checks and maintenance schedules. It's also the part of a model most worth auditing, because it's where sloppy exports quietly lose information.
Relationships. The model records which elements host, contain, connect to and depend on which others. Those links are what turn a 3D file into something you can ask questions of: "which rooms does this air handler serve?" is a relationship query, not a geometry one.
Coordination: where BIM earns its keep
No single model contains a building. The architect authors one model, the structural engineer another, each MEP trade its own — in different software, on different schedules. The central ritual of BIM is bringing those files together into a federated model: one scene, every discipline, updated as each team re-issues.
Federation is deliberately loose. The discipline files stay separate — nobody edits anyone else's work — but the combined scene exposes the questions that matter: does the new steel cut through the atrium? Do the ducts clear the beams? Did the architect's level shift reach the structural model? Finding those answers in a weekly coordination review costs minutes; finding them during construction costs change orders.
This site is built around exactly that workflow. The viewer federates multiple IFC files in one scene so you can section through the contested zones and measure clearances; the validator audits each delivery before it enters the federation; and when a milestone demands a single combined file, IFC Merge produces one federated deliverable with every discipline's hierarchy preserved.
openBIM and the IFC format
Every authoring tool speaks its own native language — Revit's RVT, ArchiCAD's PLN, Tekla's database. A project where five companies exchange five proprietary formats is a project with a translation problem. openBIM is the industry's answer: exchange through an open, vendor-neutral format that any compliant tool can read. That format is IFC (Industry Foundation Classes), an ISO standard maintained by buildingSMART, published in three schema generations you'll actually meet — IFC2x3 (still the industry's default currency), IFC4, and IFC4x3 for infrastructure.
In practice: when someone "sends you the BIM model", they send an IFC export. Which is why every tool on this site reads IFC natively, and why a browser is now a legitimate seat at the coordination table. For a deep dive into the format itself — the STEP encoding, the entity graph, version differences — our sister site maintains a dedicated guide to what an IFC file is; here it's enough to know that IFC is how models travel between tools with their data intact.
Who does what in a BIM project
BIM manager
Owns the rules of the game: which schema and export settings each team uses, what data every element must carry, how often models are exchanged, and what a delivery must pass before it's accepted. Their week revolves around receiving models, checking them and reporting — which is why an automated audit that flags a truncated file or duplicated GlobalIds in seconds replaces a very tedious manual ritual.
Coordinators and engineers
Consume each other's models constantly: the structural engineer models against the architect's grid, the MEP designer routes services through everyone's voids. Most of that work is reading models, not authoring them — opening a colleague's export, isolating a storey, measuring an opening, checking a property. Exactly the workload a free local viewer removes the licensing friction from.
Everyone else
Contractors pricing work, site managers checking sequences, clients approving designs, facility teams preparing handover — the majority of the people who benefit from a model never author one. BIM succeeds on a project when this group can open the model as easily as they open a PDF. That is, quite literally, the reason this site exists.
Three misconceptions worth clearing
"BIM is software." No single product is BIM. Revit, ArchiCAD and Tekla are authoring tools used in a BIM process; the process is the shared model, the exchange rules and the coordination rhythm. A team with modest tools and disciplined exchanges is doing more BIM than a team with expensive licenses and siloed files.
"The model is always right." A model is a claim, not a fact. Exports go wrong: properties get lost in translation, files arrive truncated, georeferencing drifts. Mature teams treat every incoming model as unverified until it's been opened and audited — trust, but re-parse.
"BIM data stays in BIM tools." The most-used BIM deliverable on many projects is a spreadsheet. Quantities for the cost plan, door schedules, equipment registers — all of it is model data that wants out. Pulling the whole model into Excel, one sheet per element class, is often the fastest way to make BIM useful to people who will never open a 3D scene.
How to start, today, for free
You don't need a platform rollout to touch all of this. Take any IFC file from your current project — or use the sample in the viewer — and run the loop once: open it and walk the storeys, drop a second discipline on top to see federation happen, run the audit and read what it flags, then extract the quantities and check them against what you thought the project contained. An hour of that teaches more about BIM than a week of slideware — and every step of it runs in your browser, with the model never leaving your machine.