Wednesday, March 16, 2016

Extend Vertical Mullions to Add Anchor Points

In most curtain wall applications, the top of the vertical mullion reaches past the floor and is fixed to the structure at, or near, the floor using an anchor.



In some cases, however, the curtain wall height doesn’t reach to the floor above and a different anchoring strategy is required.  Often, this strategy includes extending the vertical beyond the top horizontal to create an additional anchoring point.


One solution is to create a Generic Object family and place it wherever the extension is required.  In this post, we will explain how to create an extended vertical in a Revit curtain wall object using mullion profiles and infill types.


 Start by creating a Revit Curtain Wall object.  The actual size doesn’t matter; the one shown here is 10’-0” long and 8’-6” tall and represents a wall that requires a 6½” mullion extension.  From the Architecture tab, add vertical and horizontal grid lines and make sure the top horizontal grid line is 8” from the top of the wall.




Click the Application button>New>Family and select Profile-Mullion.rft to open the mullion profile template.



Create a captured mullion profile as shown here.  The procedure for creating custom mullion profiles can be found on our site in this blog post.  Name and save the file then load the profile into the Revit project.




Edit the profile eliminating the glass pocket and pressure plate, Use the Save As option to save the profile with a different name then load it into the project as well.



In the curtain wall project, select all of the panels, select System Panel Glazed as the panel type, and then click the Edit Type option.



In the Type Properties dialog box, change the Offset value to -0.5” to shift the face-of-glass to the face of the curtain wall



Click Mullion from the Architecture tab then click the Edit Type button.  In the Type Properties dialog box, click the Duplicate button then enter a name for the new mullion.



In the Type Properties dialog, change the Profile to the first profile that you created in this exercise.



Place the mullions as show below, using the Grid Line Segment option from the Placement panel.




Click the Edit Type button for the mullion, duplicate it, and then change the profile to the profile that you created without the pressure plate.



Place the new mullions in the remaining, short grid line segments.  Select the top horizontal mullions then click the Make Continuous option in the Mullion panel.  Although this isn’t technically accurate regarding most curtain wall designs, it will prevent a void from being created, on the front of the system, where the pressure plate terminates when the horizontal butts against the vertical.  In the real world, the pressure plate extends past the edge of the vertical, while it does not in Revit.  Alternately, you could create custom horizontal geometry, to replace the profile-created geometry, which adheres closer to the physical representation.



Finally, select the top three glass elements and change their type to Empty System Panel.


That’s it!  The verticals now include extensions that will allow anchorage above the top of the exposed curtain wall and can be included in clash detection operations.


Images in response to Darren's comment in the Comments section below:

Flexible unit

Parameter driven values:


  1. Very useful article! We keep running into similar Revit limitations when modelling Rainscreen and wall panel systems. The Revit model needs to be constructed in a way that reflects how it is actually going to be constructed. As a building envelope contractor we need more from the Revit model, we need to be able to construct the model in such a way, so that we can not only accurately represent the components in the model but also schedule and order the required components. To this end we have steered away from using any of the Revit builtin system family types such as Walls, Roofs & Curtain walls. We have instead gone down the Generic model route, with all of the items broken down into generic model sub-categories. Using generic models hosted, on reference planes or other items within the model, has given our families greater flexibility and allows them to be constructed in such a way so that they report all of the information required to fill in the order schedule which is sent to the component supplier. Try achieving this with a non-rectangular curtain wall panel or rainscreen panel.
    Contractors need to take BIM beyond the consultants model to more reflect the way in which the building is constructed, see my article about this at, sorry for hijacking your excellent post, it is great to see other building envelope specialists pushing Revit to meet our needs, we now just need Autodesk to provide us with more suitable tools, or just fix the ones we have so that they work the way things are constructed.



  2. Hi Darren,

    Thanks for the comment. I agree that the Curtain Wall tools in Revit could use an overhaul to better model the curtain walls that architects often envision. In presentations and classes, I sometimes show one image of a rectangular building with straight, consistent walls as a representation of what Autodesk thinks CW’s look like, followed by a real-world project with tapered walls, pop-outs, overhangs, sun shades, integrated handrails and penetrations as a contrast.
    We’ve also created models using generic objects with components that can be scheduled but we still use the curtain wall as a base object and model flexible, parameter-driven units as the infill panels (see the images appended to the post). This allows us to build units that can change should the architect or project requirements require a revision to the design. While this can fulfill a scheduling and LOD requirement for the project, it also significantly increases the file size and project time.
    If there is anything that you would like covered in our blog, please let me know.

  3. Hi,

    First of all, congratulations on the blog. It's very helpful.

    I have a doubt: what about corner mullions? I've searching around and found that we can insert detail items on profile families for higher detail level, but we can't edit corner mullions.

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