Curtain wall / mullion corners in Revit

NOTE: This workflow no longer works in Revit 2014+ – refer to the comment section on this post for a method which works in Revit 2014. 

Curtain walls are one of the first major hurdles users face when creating simple projects in Revit Architecture for the first time. An example of one of the problems you could face would be that when you create joining curtain walls through an angle, Revit does not automatically generate the best design option for you. Instead it will give you a default option as seen in the image below.

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In the above image you can see that Revit has automatically generated a faulty construction. Instead of creating a corner mullion  / join, it has simply added the 2 walls together with the standard curtain wall endings, resulting in a clash. I assume the reason for this is to allow the user the freedom to design and modify the join as they feel suitable. I will now demonstrate the very simple solution to this problem.

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Following the instructions from the image above, select one of the corner mullions, at this point lets assume it doesn’t matter which one you select (certain join options work in different ways). Once you have one selected, you can click in the properties dialogue and change the element type from the drop down menu. As you can see there are various options which you can choose from; play around with them and find out what fits your design. Once you have decided, click “apply”.

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You will receive an error from message as shown in the image above. It is just warning you that at present the new corner mullion is overlapping the neighbouring curtain region. Simply click “Delete Element(s)”. You have now removed the other mullion which was automatically generated from Revit and replaced it with your new corner connecting mullion. (Note: You will have to change the mullion type on each level)

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In a plan view, you will now see that the join is a lot cleaner and the clash has been solved. As I said above, there are a lot of different design options, so if the “L join” doesn’t fit your design then play around and find one that does. You can always create a custom family if you don’t find what you are looking for!

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Finally shown in a 3D view, the new mullions (top) and the original model (bottom) generated by Revit. As you can see the join has been cornered off and no longer clashes with the joining wall. This is a very simple design option in Revit, but it is very important to understand the basics of curtain walls before you try and create large projects with custom systems. If you are trying to create curved curtain walls but it is showing up as a straight wall in 3D view, make sure you have defined rules and standards for vertical grids on the walls, alternatively, use the “storefront” style of wall which is already pre-defined.


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About Ben Malone

Information Manager for BIM.Technologies in London

7 responses to “Curtain wall / mullion corners in Revit”

  1. Jon McFarland says :

    Hi Ben,

    Thanks for the blog.

    wrote a related post on our curtainwallBIM blog showing how to use a custom split mullion at the corners: All comments are appreciated.


  2. Jaysyn says :

    Any idea why this wouldnt work in 2014?

    • Ben Malone says :

      Hi Jaysyn,

      Thanks for the comment.

      Autodesk have changed the way curtain walls work in 2014. You can now go into ‘Edit Type’ on your wall and add corner mullions via the Vertical Mullions ‘Border Type’ parameter.

      Have a play with it – If it adds mullions you don’t need, you will have to unpin them before you’re able to delete them.

      Good luck,


      • Jaysyn Quarry says :

        Yes. My problem is that I cannot get the two perpendicular curtain walls to fully cut out the wall at the corner like your image shows. Any idea why? I swear it did it automatically in 2013.

      • Ben Malone says :

        Works fine for me. I’ve just tested it out now – If you want me to have a look at your file, send it over to me benmalone86 @ gmail dot com – I’ll have a look what the issue is.

  3. Jaysyn Quarry says :

    Any updates to this that would help? I am still having the same problem….

    • Eli Chiasson says :

      I’m not sure what test Ben did, but I have had this issue as well. The only time I have found it to completely cut out the corner of the host walls is if the curtain wall and host wall are the same width, or if the exterior faces of the curtain wall and host walls are aligned. For conceptual work this is easy to achieve, but for models that are based on real-world wall sections, it’s rare that the curtain wall is as wide as the host wall, or at least that’s my experience.

      I have resorted to editing the profile of the host wall to match the inset piece of curtain wall.

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