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Bruno Ferraz

Walls / Slabs / Windows and Doors

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Hi guys, 


I'm trying to dive into the BIM modeling to create a file for a house for the first time. I would like some help to well address some construction connections in-between some elements.

For instance, I have a slab that is normally composed by a structural element with 17cm, then a screed with 10 cm for filling purposes and also underfloor heating and then the finishing that can varies in between 2 and 3 cm. Until now, no worries.

I have managed to create the desired connection in between the exterior wall exterior component and the slab with the offset values so that the isolation could descend to the total thickness of the slab.

Nonetheless I've encountered two problems.


1# If I have a different finish in between two rooms, how do I resolve this? For instance, in one room the finish layer as 3 cm made with 2cm of screed and 1cm for some tile, and the other room is simple 1cm of cork and 2 of wood pavement. Do I need to create two different slabs? One for each area?


2# Normally the wall that divide this two spaces in my case is made of brick and it's supposed to be constructed directly over the structural slab, so it means that in my case this wall should descend 13 cm to connect with the structural core of the slab.


Can any of you guys tell me if you know how to resolve some of this issues?


Thanks in advance, 


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Hi Bruno,


1. We split the structural Slab object and the finishes Slab object onto two different layers. In fact we don't tend to model floor finishes, we usually just treat the screed as finished floor level and ignore the finishes. In your case some of your floors don't have a screed so ignoring finishes may not be the best approach.


So we tend to put a floor finishes Slab (usually just a screed) on the same layer as our main walls, and then we put the floor structure on a separate layer altogether. We don't auto-connect the slabs to the walls because we find the connections never persist. They're always getting broken because of moving walls or changing wall build ups.


So in answer to your question, yes you need at least two Slab styles. Personally I would use at least three: one for your structure on a separate layer and the others for everything you want to model above the structure (either on their own floor finishes layer or on the same layer as the main walls).


2. You can control these connections automatically by setting the bottom and top wall component bindings (under Wall Component Settings) + the slab component Edge Offset (under Slab Component Settings), and then auto-binding the slabs to the walls, but, again, we find the auto-binding approach breaks too often and slab edges don't remain where they're meant to. So what we do instead is to manually add the structural Slab object using the Polyline Mode and then edit the wall top and bottom bindings and offsets to suit (in your case you would set the brick component of your wall to bind to top of your slab). Depending on the complexity of conditions we may set the top and bottom wall components by Wall Style or we may do it for each wall manually (in practice a bit of both).


To set your levels you need to be using Stories. In each Story you can set any level you like. For instance, for your structural slab you would create a Level called Top of Slab and you'd would set the Elevation to -3 cm relative to the story (for your screed + tiles area). And, if you follow my advice, you'd also create a separate layer to go with it.


If you want all the floor finishes to be perfectly flush then you may decide to set your structural slabs at different levels to suit the finishes. But I imagine you're probably happy with 1-2 cm difference in finished floor levels between rooms, in which case you'd stick with one level for your structural Slab.

Edited by Christiaan

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^ same here. 2 Slab Objects.

Structural + Finish Floor Package.


Autobinding to styled Walls with proper component and core (!) settings

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Hello Christiaan and zoomer!

Thank you very much for the explanations! I will try to go on that direction and then I return with a proper file to show to you guys.


Once more, 

Thank you very much



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Normally a structural slabs flows over the whole Story.

Finish floors, and often the package beneath, vary between rooms.

So it is also less tedious and needs less slab styles.

And you can easily fill the finish floors into each room by paint bucket mode.


Just the door cut areas may need an extra floor rectangle.

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