Can't do Mansard roof with void extrusion

[rickowilmath]

I am doing the Mansard roof example from the "Residential Roof Design" by Mark

Sadler. This roof is constructed by creating a tall hip roof and then using a 

void extrusion to clip off much of the top and then creating another hip roof with

a different pitch on top of that roof.

I am able to create the extrusion which then lops off most of the roof but when I 

go to click the green check mark it says it can't make the roof. The warning suggests

I use the cut geometry tool but I try that I get another error notice saying it can't 

make the foot print roof. 

Any ideas?

Thanks

Rick

[barthbradley]

I don't know what technique Mark Sadler is using, but you can do a Mansard using Roof Cutoff Level.  FWIW. 

...I think waht going on in your case is that you are not cutting the roof with the In-Place Modeled Void before hitting "Finished".  The Void needs to be "attached" (e.g. cutting something) before exiting In-Place Modeling.  

[rickowilmath]

Mark Sadler mentioned the roof cutoff tool but said that the sections aren't as realistic. 

Here's a screenshot of what is going on with the void. I am able to lop off the roof with

the void but when I hit the green checkmark I get this warning

[barthbradley · Accepted solution]

Why don't you do it this way then: 

Note the Roof Sketch.  No cutting required. 

[ToanDN]

Like this?

[constantin.stroescu]

in order to be able to have a constant Roof thickness and to have a layered structure , I'd use a Mass Element created by Sweep and then Roof by Face.....something similar to what is shown in my screencast:

https://knowledge.autodesk.com/support/revit-products/learn-explore/caas/screencast/Main/Details/522...

[constantin.stroescu · Accepted solution]

the same method as in my previous post , but this video is more simplified...

https://knowledge.autodesk.com/community/screencast/1d05b733-6dfe-4414-b3e5-a53a32103624

[rickowilmath]

Barthbradley, is this an extrusion or series of extrusions?

[Anonymous · Accepted solution]

Here is an easy way. You want to create two roofs (bottom and top). For the bottom when you sketch the roof add a rectangular shape in the middle to create an opening for the top one. Then create another roof to fill in the void. Now click on "add split line" and create the border lines between the slopes for both roofs (same step for each roof). Now use modify sub-elements to change the elevations for each point. 

[barthbradley]

---

@rickowilmath wrote:

Barthbradley, is this an extrusion or series of extrusions?

---

I created a Hip Roof by Footprint and then lopped off the top of it with an In-Place Modeled Void.  

The other method I showed, was a Roof by Footprint created with two closed-loop sketch boundaries; offset from each other. The outside sketch boundary defines slopes; the inside sketch boundary does not. The end result is a Mansard. 

[rickowilmath]

Thanks everyone for the help.