Curtain walls - why centerline?

[damon.sidel]

How do you deal with curtain wall location lines? The OOTB generic curtain and storefront wall types have the mullion and glazing at the center of the wall, right? Then there are the offset parameters for both the mullion and the panel. How do you locate your curtain walls? Do you generally keep the mullion centered and change the location of the glazing? Do you make the location line at the outside face of glazing? Do you do it differently for different applications: capped, butt-glazed, true curtain walls vs. storefront walls?

I'm working on modeling a project from scratch as we transition from conceptual to schematic design phases. I'd like to set it up systematically and this is something I've always wondered about best practice. Thanks!

[Steve_Stafford]

They had to pick something to use as a way to define the relationship between the parts. They picked centered on the "line" of the wall. You can reconfigure the parts to whichever assumption you prefer. Some focus on exterior face of glazing and adjust everything so that is what the curtain wall "line" represents. It is up to us, the templates had to start somewhere. :)

[damon.sidel]

the templates had to start somewhere. :)

Fair enough. I can understand that as a starting point, so I guess the next question is "What do you do?" There must be some opinions out there about a systematic approach to defining where you place the location line and how to set the offsets.

For example, I've considered two options so far:
1. All curtain walls are defined by the exterior face... that may be the exterior face of glazing if the mullions are not capped, or the exterior face of mullions if capped. Then locating the wall is a matter of placing the location line in relation to the slab edge or other part of the building.
2. Curtain walls are defined based on their use. The location line for exterior curtain walls that are are hung are defined by the slab edge and mullions and glazing are offset appropriately. The location line for storefront walls is defined by face of glazing or some other logic.

Steve, do you have a system?

Do others have a system?

I feel like I make it up for each new curtain wall type. :(

[Steve_Stafford]

No I don't a have a steadfast approach since I don't really do the same kind of work all the time but if I did I would set up curtain walls and their components so they work they way "our" projects define them. If you have a typical vendor you work with then it might help to see which way they look at it. There is a curtain wall detailer who hangs out at the RevitForum.org mostly so you might want to post your question there too, his user name is Dave Jones if I recall correctly.

It really comes down to what you think those points mean when you click on screen, face of exterior glazing, centerline of glazing, or something else.

[Chris D UK]

The default of using centerline for curtain walls is REALLY unhelpful. Curtain walls in the real world are always set out from external face. The OOTB default results in the bizarre situation that if you have mixed mullion sizes, they don't all align with the glass!!!!

[dhurtubise]

Most of our stuff is done so that the Curtain Wall Location line is set inside because the room will stop at that line. Of course if a project requires another "location" for the room calculation then the families are built accordingly/

[Steve_Stafford]

...The default of using centerline for curtain walls is REALLY unhelpful...The solution is really simple, change the settings to what you prefer them to be in your template. Done, won't have to be annoyed by it again. :)

FWIW, I've met people who use centerline as their reference (the development team seldom make choices in a vacuum) so changing the template to suit your preference will annoy them. That's the point of using our own templates, presets that make sense for our own needs or project's requirements.