Slab underneath imported IFC

Hello all.

Ok, so I’ve got myself a real challenge here. I have an IFC file which I need to create a slab, or some kind of mass underneath it.

The IFC is all curvy and bumpy, and I need the slab to cover the whole file, but not go above it, if that made any sence. The reason being, is that I need to be able to export the created mass as an IFC, eventually create a hole/void in it, and then be able to calculate how much of that total mass the hole/void is. (For digging purposes, volume calculations).

Any idea how to solve this? I’ve tried all day with different soloutions on the internet, but I can’t really get it to work.

Thanks in advance,


Added another picture if the question remains confusing (which is totally understandable):

Hi Patrick.
See if my blogpost here can help you in any matter:

Maybe you can also post the file here and show us something of what you have already tried and not succeeded with?

Hi Jostein.

I’ve not saved any of the files with the things I’ve tried to work this out, but:

  • I’ve tried opening the IFC in Revit - Exporting it as a DWG - Importing the DWG and making it a topography surface.

After this, I’ve ran various scripts, with no success, and a lot of crashes.

I looked at your blog, and tried to do it with mine, but I couldn’t quite work it out. Does the surface HAVE to be a topography surface? Is there no possible way of creating a solid mass UNDER the curved/bumpy IFC? Does it require any special format ect?

I’m quite new to this, so I must appologize if I sound like a total noob.


I need to be able to export whatever mass I create to IFC, doesn’t matter how deep it is, as long as the top of that mass matches the imported IFC terrain.

I’ll take the bait, fellow countryman and all. :slight_smile:

Here’s one way of doing it:
I’ve opened the IFC in Revit and selected the surfacemodel with Select Model Element, then this:

Please mind that I offsetted the boundarycurve 1 cm or so inwards in order to be sure that the solid will be cut by the “topography”.
Here’s a link to the script:

Ok, some progress, but still a few faults:

The solid creates the outer shape, but doesnt cut at the top of the IFC. Any ideas?

The Point.Z node will be yellow since it’s part of a function. Have you tried reversing the offset of the boundary curve? ie give it a positive value?

Jostein, thank you so much! It worked. I think my main problem was with how I opened the IFC in Revit.

For this to work, the IFC must be opened directly to Revit. No linking, in other words.

You are a champ dude!