Forums >> Community >> Newbies >> Newbie - Roof trusses and overhangs

rltennal

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Joined: Wed, Jul 13, 2011
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Hello folks,

I have been working with Revit Architecture and Structure for about a month now.  In my current model I have a simple residence where I am trying to model the roof trusses.  What is the bet strategie, model the roof without the structure or with the structure?  What I am asking here is should I include the depth of the top chord of the truss in the roof defination.  I would think i would be wiser to model just the sheathing and finish material and come back with the trusses to model the remainder.  Especially for those case where I want to show the explosed trails... Geting the tails on the truss is another issue. 

When I first started modeling truss I was using the double slope trusses that came with the program.  Research here on RivitCity suggest that we use a Flat Chord Trusss and attach it to the roof.... this works great, except I loose my overhangs (truss tails).  Do you all have some suggestions how I can do both, have an overhange and attached the truss to the roof?  I tryied this with the Sloped trusses but the angel of the top chord differs from the actural roof.  It appears as this attachment has occured at the ridge.  Once I started using the Flat chord truss it all makes sense.  But is those curse trails.... kicking my butt.

Thanks for the help

-----------------------------------

Raymond Tennal Jr.

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nastyclown

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Joined: Mon, Jul 13, 2009
273 Posts

Well, you can always unpin some element in that truss and move it where you need, but i dont know how its going to behave when you bring it to revit structure.

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itsmyalterego

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Joined: Thu, May 28, 2009
829 Posts

It really depends on the size of the project, and the stage of design you're in.

When I start out, I use thick roofs.  A roof that's thick enough to include the top chord of a truss and the insulation.  For a long time I'm satisfied with, say, default 8" or 12" roof.  Eventually, as trusses are put in and it becomes more clear if we're going with a cold roof or a hot roof, I start thinking about thinning down the roof thickness, defining materials and layers, and placing this on top of the trusses, as it would be built. 

We don't work on particularly small projects in our office, so we're almost always working with out-of-office structural engineers.  Often, we turn off their work, and we use non-parametric trusses in the architectural model that are simple sweeps, with a truss-shaped profile.  Allows us to have exactly what we want to see, and also show structural what we expect.  

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