Dept. of Obscure: Cutoff properties

In the next two posts I'll cover two parameters and a feature both of which can solve the same problem in different ways.  This post is on the "Cutoff Level" and "Cutoff Offset" properties we find in Roofs.

In the strata of Revit features the Cutoff properties were introduced somewhere in the cretaceous.  Like a vestigial tail you might have wondered what purpose it serves.  You may have even set some values and not seen any visible change or got an error "Cutoff Level cannot be below bottom of roof".  Scary.

Essentially what these properties do is cut back or trim (perhaps better terms) a footprint roof.

Below is a progression where a roof is created, the Cutoff properties set, and then a third roof added to create a Mansard shape.

Voila!  There are other ways to do this that may or not be less steps but perhaps easier to understand.  I'll cover that in the next post.  BTW if you are developing an in-house test to plumb the Revit knowledge of your hiring candidates this could be a devious inclusion.

_erik

Comments

[x-p]

Now draw a section through that mansard. Ew! Ugly! The only way to get mansard roof layers to go round the secondary hip properly is to create a roof by Mass.

[Erik]

Right. Mass can work. There is even another way I'll cover next.

[DoTheBIM]

Erik, This just came up in another forum but if you have a curve in your roof sketch and with one or more straight lines and the curve is slope defining... the cuttoff tool doesn't work right above a certain point on the roof. I gives an error in 2009 and cuts portions out of the middle or not at all in 2010+.

[Anthony Hauck]

Can you include a link?  Ill take a look.  An alternative to the roof cutoff is adding an interior sketch loop but it could create the same problem.  Id like to check a known problem roof.

[DoTheBIM]

Sent you a link to beta forum via email.