Wall Quirks

Got very busy around here, hence my extended silence. To make matters worse, there’s Euro 2012 now so…while Zach Kron continues to chirp away at funky forms, nodes, divided surfaces and adaptive component families, I think I’m going to continue pointing out the Quirks of Revit Walls^{TM .}

When you unlock the bottom of a wall layer, you can extend it past its bottom constraint (and vice versa for the top). This functionality has been in Revit for as long as I remember. Nowadays we get a lot more control through Parts functionality if we want to fine-tune for panel joints, thickness, extents, etc. Layer unlocking is very handy when trying to rest the base of masonry veneer on a brick ledge or when you want the gypsum board layer to stop below the top of the stud layer for example.

However there is a peculiar condition that we’re presented with when we edit the profile of a wall to create an opening. I totally understand the programming logic of why, but from an architect/builder perspective, this does not make any sense at all. When the profile is edited, the bottom-most horizontal line is still recognized as the base of the wall, so if you edit the Base Extension Distance, you end up with that same extension happening at the “opening head”. And as you might have guessed, the programmer and I just don’t see eye to eye on this one as I don’t believe it should behave this way. Anyone else agree?

So in an effort to outsmart Revit, I inserted an opening instead. As you can see in the middle example above, it seems to solve the issue. However this only works if there is a positive offset value for the opening and as you can see on the right example with the opening having a negative or no base offset, the opening head is messed up once again…#fail3.

By now you’re ready to stop using the unlocked layer functionality; but wait a minute, there is a way (as always!): start an in-place wall family and create an opening in there (Revit will ask you to pick a host).

I know, it shouldn’t be this hard. We see eye to eye on that one.

When working on my first Revit project, I dealt with this same issue only to have it resurface years later while helping another team. It was actually the same exact design scenario: an exterior wall with varying “panel” finishes and continuous stud backup. The team edited the profile of one wall and nested the other in. However when the layers were subsequently unlocked and the masonry lowered to rest on the brick ledge, all head conditions messed up and started overlapping the layers of the nested wall. In such a case, your best option is to not even mess with openings and just embed one wall within another using the Cut tool in plan view, since it’s easier there.

Now when you need to adjust the size and location of the embedded walls, you won’t have to chase around the project correcting the openings as well. And the unlocked layers won’t give you any heartburn either.

Wall Quirks

Beams with sloped edges

Steven Debooy, a fellow blog reader, recently asked me if it was possible to add a parameterized void at the end of a beam to cut it at a slope. That question prompted me to write this post about how one can achieve that result.

a) Adding a void to the beam is a possible solution. I posted a family in the Structural AUGI forums in 2007. Feel free to reverse engineer it and find out how it works. My example has 2 voids instead: one handles positive angles and the other handles negative angles. The user inputs an angle in one parameter, and 2 calculated parameters evaluate that input and return the correct result.

b) In the 2009 Revit family of products, one can use the Opening by Face tool to achieve the same result. Using this tool to cut the end of a beam, one will get a warning stating that "Opening partially cuts its host". It's not a serious warning (I guess), but it is meant to inform the user that something could potentially be wrong, as usually an opening is meant to have beam material surrounding the entire sketch perimeter! This is the best option if you want to create custom shaped cuts on the fly.

c) This method makes me mad. Why? Because it's only available in Revit Structure (come on people!). NOTE: As of the Subscription Advantage Pack, this functionality is also available in RAC2010. Thanks Factory!  Aaaanyway, You can sketch a reference plane and then use the Cut Geometry tool to trim the beam against the reference plane (actually you can also trim against a grid). Non-linear cuts are not possible with this technique.

Beams with sloped edges

Oh, that Options Bar

The Options Bar catches all of us by surprise. No matter how many times we glance at it, there's always something new to discover, regardless of the number of years or months you've been using Revit.

I've been slowly modeling our house in Revit. Slowly, because you know how it works: the last thing you want to do on your weekend is more Revit and Architecture haha. Plus you realize that what you'd like to do to your house is probably not something you can afford! But now I have other reasons for needing floor plans, so I have a good incentive to get it done. As I was working, I needed to edit a window, so away I go into the familiar family editor. Inadvertently, I selected the opening and something caught my eye. Now you might have been aware of this, but I have to confess that it was the first time I saw it! And no need to check whether it's a new feature...it was there in 2008 and 9.1! Sheesh.


You can set an opening cut in hosted families to be transparent in 3D and/or Elevation. Above you can see the default settings. The reason I wasn't aware of it was possibly because material transparency is not respected in elevations. A common technique to get window glazing to show transparent in elevation is to use a 3D view oriented to an elevation, and thus the opening shows transparent due to the setting above. That's my excuse and I'm sticking to it!

So hopefully you'll learn two things from this post:

1. Opening transparency in hosted families can be controlled for 3D views and Elevations;


2. Keep an inquisitive eye on that Options Bar because you never know what could be hiding in plain sight!

Oh, that Options Bar