Toposolid filling foundation window void

[cgoossens_81]

Hello Autodesk Community!

Revit LT user still using RVT2023. Playing around in the new 2025 with toposolids/excavation etc. I avoided 2024 due to some of the issues being reported with the toposolids, not having access to building pads or mass voids etc. But I had some time so I decided to give 2025 a try.

I like the excavate feature as an alternative to having a separate floor and building pad, but I'm finding that the toposolid is automatically filling the void in the foundation wall created by a window or door...Ugh. So close.

The window family itself can only cut the host wall as far as I know, and joining the host wall to the toposolid doesn't help. I could extend the basement slab to the exterior face of the foundation wall, or the window well gravel "floor" into the wall, but obviously this looks incorrect in section views so I would have to do some work in the sections with linework, filled regions, etc. 

The best workaround I've found so far is creating a 1mm thick "floor" at the sill of each below grade opening and using those to excavate that little slice of toposolid. It works, but...

I'm sure I'm not the first person to have encountered this. Anybody have a better solution? 

[olmstead]

I have run into this same bug and have some more details and an example file.  The problem seems to be that the voids in walls that cut topo fill up with topo. This becomes evident when you cut on either side of wall with either excavation or a void.  In the attached example revit file, a wall sits on a footing with a slab poured on either side, a common situation.  When the toposolid is isolated (TOPO.jpg), you can see the cuts from the floor excavation, wall and footing cut, however the voids in the wall cut by the window and door have mysteriously filled up with toposolid.  Bottom line is that if you put doors or windows below excavated grade, you will have to add a cut with a void to remove the floating topo in doors and windows.  The example is 2025 but the same issue exists in 2024 with void cuts instead of excavation. 

[olmstead]

This is what the wall looks like with a fix, i.e. adding a void cut to remove the floaters. I think, unfortunately, you are best off just sticking with void cuts instead of using excavation or wall cuts since neither works correctly.  Curiously, when applying the void cut as a fix, I got a warning that no geometry was being cut from the toposolid even though the floaters disappeared after the cut. 

[cgoossens_81]

Unfortunately I'm just a lowly sole practitioner using Revit LT. It doesn't have a tool to create mass voids so this doesn't work for me 😞

[Base12]

It doesn't work for the full version either, you're not missing anything.

[jseltzer]

This is what happens when coders design programs and don't know what happens in real world situations. if an architect designed the program, they would obviously know that the toposolid would go around the footing and up the exterior side of the wall. pretty simple concept.  What i've done is put a very thin "floor" under the portion of the exterior wall so the toposolid gets cut out and looks right... just another Revit  workaround. how about they spend more time on practical issues instead of the stupid stuff they add like the Energy Optimization nonsense that i'm sure 99% of revit users never even look at

@jseltzer - this post has been edited due to Community Rules & Etiquette violation.