IFC, RVT, NWD Walkable Clearance Check

Detect walkable surfaces from geometry (no IFC class trust), then flag any element encroaching into the headroom zone above them.

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.

Find the places in an IFC model where you can't stand up. Upload the model and the check identifies the walkable surfaces, then reports every patch of floor with less than your required headroom above it — the duct crossing a corridor, the beam over a doorway, the pipe run at head height in a plant room.

Headroom failures are hard to see and expensive to find late. They don't appear as clashes, because nothing intersects — the duct is perfectly placed and the floor is perfectly placed and the gap between them is 1.9 metres. Nobody notices until someone walks the building, and by then the duct is installed.

When to reach for it: When you need to verify ceilings, ducts, beams, signage, and other overhead elements maintain the required headroom above every walkable surface — without trusting IfcSlab / IfcStair labels, which are often miscategorised.

What you get: An HTML report listing every element that drops into the clearance zone, a CSV for pivot-tables, and BCF 2.1 for any BCF-compatible coordination tool. Optionally open the same violations directly in BIMCamel's BCF viewer.

Example: Find every duct, beam, or pipe that drops below 2.1 m above a floor or stair landing.

It finds the floors first

The check doesn't assume slabs are the walkable surfaces. It identifies walkable geometry from the model's actual surfaces, using a normal-deviation limit — 10 degrees by default — to decide what's flat enough to stand on. That picks up the landings, platforms, walkways and roof surfaces people actually use, and correctly excludes the sloped and vertical faces they don't.

Two more thresholds keep the output readable. Surfaces are grouped into elevation buckets (50 mm by default) so a floor modelled as many pieces at slightly different heights is treated as one level rather than dozens. And a minimum patch area (50,000 mm² by default, about 22 cm square) means trivial slivers of geometry don't each become a finding — the report describes places you could stand, not every fragment of surface.

Set the height for the space, not the building

The default clearance is 2100 mm, a common minimum habitable headroom. It's the wrong number for plenty of real questions, which is why it's editable — and choosing deliberately is most of the value of the tool.

2100 mm — habitable headroom, the general-circulation default.
Higher — a plant room where equipment needs lifting, a corridor with a service zone above the ceiling, a space with a specified minimum clear height.
Lower — a crawl space, a service void, or an under-stair area where the question is access rather than standing room.
Maintenance access — set the height a technician needs to reach and work on the equipment, which is usually more than standing height and is the check nobody runs until commissioning.

Reading and issuing the results

Each finding is a patch of walkable surface with insufficient clearance, so clicking one isolates the location in the 3D view and you can see what's above it. That's the difference between a report you act on and a list of coordinates: the answer to "what's causing this?" is visible immediately.

Results export as HTML, CSV or BCF, so a headroom failure in a coordinated model can be raised as an issue against whoever owns the offending service. It pairs naturally with Clash Detection's Clearance mode, which asks a related but different question — that one measures the gap between two specific element sets, this one measures the gap above every surface you could stand on. Run this on a federated model, since headroom is almost always architecture versus MEP.

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.

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 check walkable clearance and headroom in an IFC model

Upload your model (IFC, RVT or NWD)
Set the required headroom (default 2.10 m)
Optionally pick which elements to check against — by class, saved search, saved selection, or current viewer selection
Click Detect surfaces to preview walkable patches in the 3D viewer (optional)
Click Run to clash-check and download the 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

How do I check headroom in an IFC model?

Upload the model, set the clearance height you need (2100 mm by default), and run. The check identifies the walkable surfaces and reports every patch with less than that clearance above it, each one clickable to see what's causing it.

How does it know which surfaces are walkable?

By analysing the model's surfaces and their orientation — anything within 10 degrees of flat by default counts as walkable. That catches landings, platforms, walkways and roof surfaces, not just slabs, and excludes the sloped and vertical faces nobody stands on.

Can I use it for maintenance access rather than headroom?

Yes, and it's one of the better uses. Set the height a technician needs to reach and work on the equipment — usually more than standing height — and you get the access problems that otherwise surface at commissioning.

Why doesn't clash detection find these?

Because nothing intersects. The duct is correctly placed, the floor is correctly placed, and the 1.9 m between them is a clearance failure rather than a clash. Clash Detection's Clearance mode measures gaps between two specific element sets; this measures the gap above every walkable surface.

Why are small areas not reported?

A minimum patch area (50,000 mm² by default, about 22 cm square) filters out trivial slivers of geometry so the report describes places you could actually stand rather than every fragment of surface. Surfaces at nearly the same height are also grouped into 50 mm buckets so one floor doesn't read as dozens of levels.

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 Walkable Clearance Check free?

Yes. IFC Walkable Clearance Check 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 Walkable Clearance Check?

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.