IFC, RVT, NWD Clash Detection

Find where IFC building elements intersect or are too close to each other.

Besides IFC, this tool takes Revit (.rvt) and Navisworks (.nwd) files, with no Revit or Navisworks licence. Drop one in and it is converted to IFC first, then the tool runs on that IFC; your original file is not changed.

Run clash detection on an IFC model online, in your browser — no Navisworks licence, no desktop coordination seat, nothing to install. Upload a federated file (or merge the discipline models first), define which elements to test against which, and get every intersection and near-miss back with a severity, a 3D drill-in, and a BCF 2.1 export that round-trips into any coordination tool.

Clash detection is the check that catches the expensive problems before site does: the duct running through a beam, the pipe buried in a wall, the sprinkler main with no maintenance clearance. The usual answer is a four-figure desktop licence for a tool most small studios and solo coordinators only need a few days a month. BIMCamel runs the same job — hard clash, clearance, and duplicate detection — free in the browser, and it imports the Navisworks Clash Detective XML you may already have.

When to reach for it: When you need to find where building elements intersect or are too close — like pipes through beams or ducts crossing walls.

What you get: An HTML clash report grouped by class-pair and storey, a CSV of every clash pair for pivot-tables, and a BCF 2.1 file with one issue per class-pair group for round-tripping into any BCF-compatible coordination tool.

Example: Find all places where pipes intersect with walls or ducts.

Set A vs Set B: four ways to pick the elements

Each clash test compares one group of elements (Set A) against another (Set B). You build each set from whatever's easiest for the job — the tool reads the model first and shows the real IFC classes it found, so you tick actual groups rather than guessing names.

IFC Classes — tick the classes on each side (e.g. IfcPipeSegment on Set A, IfcBeam on Set B) to scope a run to the discipline pair you care about.
Saved Search — point a set at a saved search so the test always targets the same rule (all fire-rated walls, everything on level 3) even as the model changes.
Selection — reuse a saved selection of hand-picked elements.
Current Selection — clash exactly what you've highlighted in the 3D viewer right now.

Three test modes: hard clash, clearance, duplicates

Hard clash — reports pairs whose geometry physically intersects, ignoring overlaps smaller than the tolerance you set (default 10 mm, which matches common BIM tolerance conventions). This is the classic pipe-through-beam check.
Clearance — flags pairs that are too close without actually touching, within a gap distance you set (default 50 mm). Use it for maintenance access, fireproofing, or structural cover; an option excludes overlapping pairs since those are already hard clashes.
Duplicates — finds elements that look like copies of one another inside Set A: bounding-box centroids within a tolerance (default 50 mm) and volumes within a similarity ratio (default 90%), optionally requiring the same IFC class. Duplicates self-compare within Set A, so there's no Set B.

Bring your Navisworks setup — or save one here

If you already coordinate in Navisworks, you don't have to rebuild your matrix. Import a .xml exported by Navisworks Clash Detective and the clash tests (and their search sets) come across; export the current matrix back out for round-trip review. Tolerances are converted from Navisworks' metres to BIMCamel's millimetres automatically, so a duct-vs-structure test keeps the setting you gave it.

You can also save the whole test matrix as a named clash setup and recall it on a future model — a coordinator's standard Architecture-vs-MEP battery, ready to re-run on every revision — or export it as a JSON file to share. Saved setups show up in your workspace alongside your files, and clash detection runs as a step inside a saved pipeline, so merge → clash → notify can re-run itself on each new upload.

Results: severity, 3D drill-in, and a BCF 2.1 report

Every clash comes back as a finding with a severity. Click one and the viewer isolates both clashing elements and drops a marker sphere at the intersection point, so you're looking at the exact conflict instead of scrolling a list of GlobalIds. The finding list carries the element types, GlobalIds, and location for each pair.

Download the results as an HTML report that opens in any browser (no BIM software needed), a CSV for pivot-tables, or a BCF 2.1 file that round-trips into any BCF-compatible coordination tool — CSV and BCF export need a Pro or higher plan. BCF topics can be grouped one-per-recurring-pattern ("Pipe × Wall, 47 pairs") to summarise a big run, or one-per-pair to track and close each intersection individually. Pro accounts can add a company title and logo to the report, and you can push the findings straight into a BIMCamel collaboration room for the team to work through.

Using it on Revit and Navisworks files

When you open a .rvt or a .nwd file here, BIMCamel converts it to IFC on the server and brings you back to this tool with the converted model loaded. Element ids, levels and properties come across under their Revit and Navisworks names, so pick properties as they appear in your model. Your .rvt or .nwd itself is never edited: a tool that changes the model gives you an IFC back.

On Navisworks files: About one element in eight comes through as a generic proxy; add IfcBuildingElementProxy to a clash group, or pick by property, if elements seem to be missing.

Revit files can be up to 25 MB without an account, 100 MB with a free one and 200 MB on a paid plan. Navisworks files can be up to 25 MB without an account, 100 MB with a free one and 200 MB on a paid plan, and they open in the browser viewer at the same sizes. Revit projects saved in Revit 2021 to 2027 are supported.

How to run IFC clash detection online

Upload your model (IFC, RVT or NWD)
Define clash tests: select Group A and Group B element types
Set tolerance and clash mode (hard clash or clearance)
Click Run to detect intersections
Download the clash report

Under the hood

BIMCamel parses IFC files in the browser using the open-source web-ifc engine and renders models with @thatopen/components + three.js. Heavy operations (clean / optimise / validate / convert) run on disposable server-side workers using the same web-ifc stack plus our own .NET pipeline; results stream back to your browser as soon as they're ready. Uploads sit on our servers only as long as your tier's retention window allows and are never used to train AI.

Frequently asked questions

Is there a free online clash detection tool?

Yes — this page. Upload a federated IFC, define clash tests, and run hard-clash, clearance, and duplicate detection in your browser. No Navisworks licence, no desktop coordination seat, and the free tier covers everyday file sizes.

What's the difference between a hard clash and a clearance check?

A hard clash is where two elements physically intersect — a duct through a beam. A clearance check flags elements closer than a gap you set (default 50 mm) without touching, for maintenance access, fireproofing, or structural cover. Hard clash uses a 10 mm overlap tolerance by default.

Can I detect duplicate elements too?

Yes. Duplicates mode finds elements that look like copies inside one set — bounding-box centroids within a tolerance (default 50 mm) and volumes within a similarity ratio (default 90%), optionally requiring the same IFC class. It's a fast way to catch double-modelled elements before they inflate counts and file size.

Can I import my Navisworks clash tests?

Yes. Import a .xml exported by Navisworks Clash Detective and the clash tests and search sets come across, with tolerances converted from metres to millimetres automatically. You can export the current matrix back to the same format for round-trip review.

How do I clash different disciplines against each other?

Merge the discipline models first (the Merge tool takes up to 10 files), then build each clash test's two sets from the IFC classes, a saved search, or a viewer selection — for example IfcPipeSegment against IfcBeam — and run.

Can I export the clashes as BCF?

Yes. Results export to BCF 2.1, so every clash round-trips into any BCF-compatible coordination tool as an issue. Topics can be grouped by recurring class-pair pattern or one per clash pair. BCF and CSV export require a Pro or higher plan; the HTML report is free.

What's the maximum IFC file size?

Up to 25 MB as a guest, 100 MB with a free account, 500 MB on Pro, and 1 GB on Team. The caps are on upload size only — every tool itself is available on every tier.

What happens to my file after processing?

Your file is uploaded over HTTPS and processed on our servers. Guest uploads are stream-only — the working files are deleted as soon as your download finishes. Free accounts keep results for 7 days; Pro and Team keep saved models until you delete them. Files are never shared with third parties or used to train AI.

Is IFC Clash Detection free?

Yes. IFC Clash Detection is free to use — guests get 3 runs a day with 25 MB uploads, and a free account raises that to 10 runs a day with 100 MB uploads. No trial clock, no watermarks.

Can I use a Revit or Navisworks file with IFC, RVT, NWD Clash Detection?

Yes. Open a .rvt or .nwd file and it is converted to IFC first; the tool then runs on that IFC and your original file is not changed. On Navisworks files: About one element in eight comes through as a generic proxy; add IfcBuildingElementProxy to a clash group, or pick by property, if elements seem to be missing.