"Two Cut - Square" Rafter Cut won't appear with Roof by Extrusion

[cmpaynedesign]

Hi All,
We're working on a project with a butterfly roof (see image 1) and are finding it impossible to create a roof by extrusion with square cut rafter ends. Normally I would use a roof by footprint, but since our roof pitch varies depending on the width of the building, the roof by extrusion would save us an awful lot of slope calculation and other inaccuracies. I've tried to fix this by setting the facia depth to match the roof thickness (this works perfectly in a roof by footprint) but it remains plumb cut (see image 2).
Any tips would be greatly appreciated!

Working in Revit Architecture 2011

[renogreen]

I recently ran into a similar situation with a barrel vault roof, made by extrusion. The effects of the plumb cuts didn't work the way we wanted. I decided to re-create the roof using an in-place family. By doing that I had the flexibility to create the rafter ends the way I wanted.

[contact.andrewk968454]

What if you started with a flat roof and used the modify points method with spot elevations?

[cdatechguy]

In order to create the square cut rafter effect with an extruded roof you need to create a void sweep and cut it from the roof...

Lots of good info and suggestions about this exact issue can be found here (http://www.revitforum.org/architecture-general-revit-questions/3554-help-roof.html).

[cmpaynedesign]

renogreen: an in-place roof would work perfect, but unfortunately we need the roof to contain the "layers" of structure that are associated with a standard roof types. tom my knowledge, in place roofs loose don't contain layers at all.

contact.andrewk968454: the slopes of our butterfly roofs are defined by the width of each building, with a typical height for all exterior wall top plates and a typical minimum interior ceiling height (the bottom of the "V" of each roof). This means that the slope of each roof will be varied (wider building= less slope), and will therefore never have a clean, accurate number for pitch or angle. Creating an accurate roof by spot elevation and modify points would exceedingly difficult in the case of our project, but would probably work everywhere else.

cdatechguy: this is what i was afraid of, but appears to be the best solution.

thanks for all the great suggestions!

[renogreen]

Actually, they do contain those layers. You construct a roof in-place, one extrusion or void at a time. Each extrusion is a layer of material. Create the decking extrusion, then the rigid insulation, then the roofing, just as an example, using the materials you already have in your materials library. If you need to use a void, you create one of those. You can create as many layers of materials or voids as you need before you finish the in-place family.

[cdatechguy]

Another method, similar to Renogreen's (and its one of the methods I suggested in the link I provided)...its not really an in-place model...your just using multiple roofs, walls and ceilings (soffits) to create the final product. I use this method for some creative roofs in ArchiCAD...
(Group them all together in case you have to raise or lower the plate height.

While it would be nice to have all the layers in one roof, they don't always work the way you want...separating everything helps....especially if you have a roof with outriggers of different sizes than the main roof rafters.