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Post your wishes about Graphisoft products: Archicad, BIMx, BIMcloud, and DDScad.

WISH: Intersection of same building priority materials


Hello everybody,


I wish we could change the order/priority of element intersection for elements that have Building materials with the same priority or the same Building materials.


From the helpcenter: 

"When various, colliding construction elements have the same intersection priority (for example, elements that have the same building material), the following intersection order will prevail:

Morph > Column > Beam > Slab > Wall > Shell > Roof > Mesh"


I would like to be able to choose that Morph > Slab > Beam > Column > Wall > Shell > Roof > Mesh, for example. So I want this not to be hard coded but I want to be able to choose the order.


Example: I have a RC beam in an RC slab, with same materials. The beams is stronger than the slab, so when making the BoQ through automatic extraction of quantities with Schedules, the quantity of concrete in the beam and the slab are not right, as we have 2 different prices and BoQ listings for the 2. The quantity of concrete in the beam should not contain the concrete that is in the intersection beam - slab, instead it should be calculated in the slab quantity of concrete. We use a workaround now, we have multiple BM "concrete" with different names and intersection priorities for wall, slab, beam, column, and so on. But it gets hard to manage and it simply is not right.



There're two ways to solve this challenge:

1) The easiest one is as you are doing when you let slab & beam with the same BM and even the same layer only duplicate BM with different name and a higher priority for the slab.

2) The hardest is to keep slab & beam with the same BM without duplicating or changing priority but only differentiate between them by different layers & different leyer intersection group number then use SEO to subtract manually beam from slab.

AC 27 INT 5030/WIN 11
AMD Ryzen 7 5800H with Radeon Graphics 3.20 GHz 16.0 GB

Yes, number (1) is a viable workaround we use, but it still brings a lot of confusion when modeling and doing quantity estimating, and it simply is not right.

Number (2) I don't think it is at any level doable. By this I mean there are too many SEO operations to handle, both when modeling them and later managing them. I think too many SEOs could bring to a slower project file, longer loading and rendering times, rebuilds, and so on.


I hope something will be implementned just as in my wish.

Hi Dawuhr,

make a composite beam (like in reality)!

Underneath ceiling use prefab-rc-BUILDINGMATERIAL with HIGH intersection-value.

In the ceiling use a BUILDINGMATERIAL with VERY LOW intersection-value.

So the slab will go through, the beam will have dimensions as in static calc.

Its like in reality.

In layer-manager both layers (if at different ones) must have same cut value, but NOT both = 0.

For BoQ use VOLUME (conditional OR net)

I checked it, at my side it works properly.

In PROFILE-Manager you can use MODIFICATOR for width, height and custom MODIFICATORs.

Best regards

In reality it is not a composite beam (or complex profile with 2 different rcc materials as you mean it), it is the same material all around. We can put your workflow toghether with the other workarounds.

Yes, it does the job, it works just like the other 2 methods, but again, it is a workaround with extra steps (modifiers to adjust) and extra steps are always critical when modeling beacuse most errors happen there.


One thing this wish could bring us, is it would get us rid of the need of another sloppy workaround.

Hi Darwuhr,

okay okay, I looked for a more simple solution,

Use rcc-material (only one BM anymore, as you want),

profiled beam (best solution in case of later changes, thats my opinion),

raise the height of the profile (NOT the heigt of tthe rcc-hatch) so that thickness of slab is incl.,

offset it down acc. slab thickness and put some FIXPOINTS (maybe called HOTSPOTS in INT-version)

refernece-point of profile TOP-MIDDLE (Put FIRST FIXPOPINT here).

Thats definitvely close to reality and absolutely NO workaround and very safe in handling.

Quantities related to dependentcies, order/priorities, thats dangerous from my point of view, but:

2 men have 3 opiniens (at least) ;--)

Best regards.


Maybe this will Help:




Gary Ford
Self Employed - Modeling, Estimating, Construction
Archicad 12-26
AMD Ryzen 9 5900X 12-Core Processor
3701 Mhz, 12 Core(s), 24 Logical Processor(s)
(RAM) 128 GB