Forums >> Revit Building >> Technical Support >> How to model a warped roof?

Devonshire

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Joined: Wed, Nov 28, 2007
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Fairly routinely, I need to model a panelized wood roof in a classic tilt-up building.  In the real world what they do is camber some of the girders and usually change the heights of the end of the girders and purlins to create a slope to drains or scuppers.  This geometry is actually a warped or "potato chip" kind of surface in areas. 

Another challenge is the simple acrylic domed skylights which are a "stretched bubble shape".... it looks simple when standing there looking at one, but an accurate model representation of the compound curves is actually very difficult right?

I ask these question because I need to have an accurate real-world version rather than the classic 2D drawing strategy of just showing a representative likeness that is "close enough"... 

I haven't experimented with the massing tools that appear to allow a warped shape, but

1. is it possible to model a warped shape?

2. Will a section show any layers of material?

3. Is the warped shape a uniform thickness?  I.e. the top and bottom are parallel at any one point (not flat on the bottom).

One approach is to carfully model the roof's framing, then try to model just the plywood and roofing over that as closely as possible with lots and lots of faceted surfaces.  The roof girders, beams and joists tend to be "rational" solids so are easy enough to model, the difficulty is really in placing all the similar components at slightly different slopes and positions.  That sounds painful from a time required standpoint. 

I have the Revit Structural 2012, but don't know to what extent this is more automated and useful to model the sloped and cambered framing .... If it is, then I need to fire it up and figure it out.

Any help from the master modelers is appreciated in advance!

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Typhoon

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Joined: Tue, May 22, 2007
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Some screen shots of what you want to do will help but you can create that with mass then apply roof by face or with "Create-in-place" in roof category, use the "Solid Blend", you can create differents blends with different materials and dif. thickness, so when you create a section view you'll see dif. layers.

Hope this help

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Devonshire

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That is interesting....

There are no screen shots to be had as I haven't tried modeling it yet.

I will investigate using the massing tool and then how to apply a roof to a mass's faces to see what is possible.

If you could do a step by step, that would be enourmously helpful, not just to me but to many.

The geometry of the roof.

It appears to be a barrell vault with a shallow curve.

The long edges of the barrel vault go up and down in straight lines against the parapet to create cross slope to various scuppers.

The curved ends of the shallow barrell vault transitions to a variably curving roof that slopes both down to the axial end at the parapet and also to the outside corners.

All the intersections with the rectangular parapet are straight lines.

Those are the geometric elements.  Easy to draw in 2D in AutoCAD!  Hard to model, especially with a constant uniform thickness.

I am also investigating if Revit Structure can handle (automate) the Girders (big cambered [i.e. curved] glulams), purlins (4x14's @ 8'-0" OC) and the numerous 2x4 joists @ 2'-0" OC.  The modeling challenge is that all the indivisual members are slightly different slopes and heights.... then how to tightly marry the plywood and roofing over that?

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Typhoon

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Joined: Tue, May 22, 2007
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First you said you want "This geometry is actually a warped or "potato chip" kind of surface in areas" roof, now you want "The geometry of the roof. It appears to be a barrell vault with a shallow curve."

Ok, watch this:  http://screencast.com/t/9Y0VvA3CEh , I create this video to other person many months ago and this is not a "Barrel Vault" it's a "Rib Vault" but the process is the same...

Hope this help

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I Hope and I Wish to LEARN  more, and more, and more.... REVIT

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