Understanding Curtain Wall Grid Logic

[chughes]

Can someone ELI5 the logic behind curtain wall grids.  I just need to talk this through so I understand.  I have my curtain wall set up as desired.  Image and properties are below.

I would like to convert the mullions adjacent to the door to the thicker border mullions.  However, when I do, Revit creates a new mullion line unprompted.  See below.

Why would Revit create this new line, especially when I have the horizontal grids limited to 1?

[barthbradley]

Sounds like you are not adding "One Segments", but instead "All Segments".  

Or, are you just trying to swap out individual mullions for a different one by unpinning and selecting different Type from drop-down?  

[chughes]

Unpinning and swapping out the Type was the plan

[ToanDN]

Are you saying that a new horizontal grid appeared as soon as you unpinned and changed a vertical mullion type?

[chughes]

Correct

[ToanDN]

Change the Vertical and Horizontal grid number under the curtain wall type to None.

[SteveKStafford]

Some basic concepts for future use...

The stock templates have three curtain wall types; Curtain Wall 1 (no preset preferences), Exterior Glazing (preset x/y pattern for grid) and Storefront (preset grid pattern and mullion sizes).

The Storefront type is the fastest path to a complete curtain wall assembly while the Curtain Wall 1 type is the slowest (we have to place grids and mullions separately). The Storefront approach works best when the pattern layout is simple. The Curtain Wall 1 type is the most flexible (more work) because we have to place all the grids and mullions (and panels).

When the type has preset grid pattern and mullion choices, to make changes we must unpin those elements to override those presets. When a new grid is added the mullions choices made are applied automatically to the grid. An override can be restored by pinning the element again (grid/mullion or panel).

[chughes]

Changing to none and leaving the generated grid lines in place, then changing the mullion to the different size works.  Any idea why it wants to throw the new horizontal in, though?  You would think a defined horizontal count would override all.  1 = 1, not 1=1 except when changing mullion sizes then 1=2...

[barthbradley]

It doesn't sound like you want any assigned default mullion.  Why not just add/change segments/mullions?   

[ToanDN · Accepted solution]

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@chughes wrote:

Changing to none and leaving the generated grid lines in place, then changing the mullion to the different size works.  Any idea why it wants to throw the new horizontal in, though?  You would think a defined horizontal count would override all.  1 = 1, not 1=1 except when changing mullion sizes then 1=2...

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I don't know. 

It could be that the grid before you attempt to change the mullion type was already a custom one, and not based on the type settings, so any changes to the curtain wall would trigger unexpected results.  For that reason, if the grids are to be placed manually, keep them as None.