Change Base Constraint, offset and mullions problems in a curtain wall

[real3dvision]

Hie,

I am changing the base constrait of a curtain wall. The problem stars when i try to change base offset. Appears this message.

Could you tell me how i can solve that problem?

Regards

[agueda_contreras_garcia]

Apparently with the Base Constrain change you are doing one of the Curtain Wall grids it's out of the wall. Check the Type constrains of the Curtain Wall or try Unconnecting the Top Constrain before changing the base.

Hope this helps, but can't tell you exactly what's going on without seen it.

[lucdoucet_msdl]

@real3dvision 

I suspect you have a manually placed curtain grid which is constrained (by a locked dimension or other relationship) to an automatically generated curtain grid. This grid also has a mullion family associated to it, therefor the "Can't create Curtain Wall Mullion" part of the error.

When to reassign the base offset, the constrained curtain grid is being pushed off the limits (either above/below or left/right). Revit is then saying that the curtain grid can't exist outside the wall "The portion of the curtain grid it was placed on no longer exists".

To correct, find and disable the constraint using an elevation view of the wall and hit the display display constraints icon:

In this case, the center height automatic grid was pushing the constrained grid line above the top of the wall:

Hope this helps,

-luc

[real3dvision]

Thanks so much @agueda_contreras_garcia ! The curtain wall hasn´t Top Constraint. I am doing something wrong?

Regards

[real3dvision]

Thanks  a lot @lucdoucet_msdl . I try it but in constraint display nothing shows up.

The purpose of all this is to change the constrait level of the curtain wall to the one indicated by the BEP. I know how do it when i export to IFC but i like know how to do it in Revit directly.

Regards

[agueda_contreras_garcia · Accepted solution]

You can try this:

1. Before changing levels

   • Delete mullions (temporarily) → change the wall’s base/top constraints → then reapply mullions.

2. After changing levels

   • Check if curtain grids have shifted or disappeared. If so:

     • Add back missing curtain grids.

     • Use “All Grid Lines” option when applying mullions to regenerate them quickly.

3. If it’s a type with automatic mullions

   • Edit the curtain wall type properties and assign mullions under “Vertical Grid” and “Horizontal Grid.” That way, when the geometry regenerates, mullions will auto-populate instead of disappearing.

In short: Revit isn’t “losing” your mullions for no reason — it’s because changing the base level forces a rebuild, which wipes mullion hosts. The safest workflow is: remove mullions → move wall → reapply mullions.

Anyway, also an option it's to check in the error report which exact elements are being deleted (element ID), it can help find the exact reason of the problem (like if there is any constrains like @lucdoucet_msdl mention).

[lucdoucet_msdl · Accepted solution]

@real3dvision 

The elevation view reveals that the wall has either a top constrained to a sloped roof (A below ) or has a profil. I suspect the former. These types of constraints are not highlighted by the Reveal Constraints view setting. The only way I know to check is to select the wall and using the detach function in the wall modify icon group.

So if you change the base elevation more than the height of the lowest part of your wall B>A, you will have a self intersecting wall profile which generates the error.

If so, detach the wall top constraint to the element above, change the base offset and reassign the wall top constraint after changing the roof height.

-luc

[mari.shimode]

Hi @real3dvision, how are you doing? Please reply if you still need assistance. If you have solved the issue, please click the Accept Solution button so that others who have the same question can find the information easily. Thank you.