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Roof Construction


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Can someone tell me what I should keep in mind when creating a house plan in Vectorworks to avoid the error massage,

"Could not create roof, house drawing to complex to compute roof"

It seems like every time I create a plan with more then one offset room I get this message. It's frustrating because I'm force to change the plan just to comply with the program.

Please Help!

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The create roof command is fine when it works but that is all too rare, still.

It often hiccups on co-linear bearing lines.

The "middle bits" can't be adjusted except through their relationship to the bearing lines. For example, there's no way to set up a roof to have parallel ridges with a cricket between. Or, after subtracting out a hole in the roof for a smaller upper story, there's no way to adjust the upper roof lines to reflect the rational adjustments to the roof that "keeping water out" would require. (see example "Hip2Wall")

There's often odd and irrational no-go areas for bearing lines. (see example "NoGo")

The good news is you can still draw any (planar) roof shape you want with the roof face command.

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Often I use the Create Roof command, to get the major forms,

then UnGroup it. It will ask you "Are you sure you want to ungroup high level objects?"

Hit yes and then you are given a bunch of Roof Faces, which can easily be edited to get your final product.

I think that strategy would work well for you in this case.

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I agree with gmm. I suggest using the Roof Face command instead.

Start by creating discrete polygons for each roof face you want to create, then run the command on each polygon. You will have better control and are not limited to the somewhat annoying hip roofs that the Create Roof command limits one to.

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Often I use the Create Roof command, to get the major forms,

then UnGroup it. It will ask you "Are you sure you want to ungroup high level objects?"

Hit yes and then you are given a bunch of Roof Faces, which can easily be edited to get your final product.

I think that strategy would work well for you in this case.

Yes, this old chestnut helps (me) in a few percent of cases.

Except when the initial geometry chokes the command.

And, if you figure out how to adjust your initial geometry to suit the command such that "create roof" succeeds, the only useful bit left from ungrouping this roof object is (usually) the roof faces. The fascia and soffits are a mess of (#+*^&$) nurbs surfaces that defy rational stretching.

So in the end I delete the fascia and soffits and redraw my own with editable shapes (walls or extrude along paths), after readjusting the roof faces to undo the changes I made to get the create roof command to "succeed" in the first place.

Around the block to get next door?

My point in posting the examples was to show the OP that the create roof command isn't just technically deficient or buggy, but that it is also conceptually very weak. It's too easy to believe that NNA would only provide a tool if it was in fact useful, and thus spend lots of time pounding it to fit.

NNA doesn't (for obvious marketing reasons) go out of their way to disclose weaknesses. Several years ago, one of the program's paradigms (it was in a Flaherty interview, I seem to recall) was to be "self-discoverable" by a reasonable user with a manual. Now the mantra is "get training". I think a big part of this change is the roll out of ever more complex features that have very narrow applications, with serious, undisclosed, and unknowable pitfalls outside of their target range. I'd say the create roof command currently falls squarely in this category.

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Chad, I second your point & would add the stair, window & door PIOs to the list. How often have I used a PIO that has to be UNGROUPED & altered, in some cases it is faster just to draw a 3-D poly? Probably more than I care to think.

Why offer a tool that one must constantly insert metaphoric pieces of blank paper overtop to produce acceptable drawings is beyond me. For the most part PIO's are handy to find where an object is & what it intersects in three dimensions, but is quite limited in its ability to render acceptable graphics. But hey, I live in hope that one day these things will make my work easier.

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I do what Gmm18 does as well. For soffit I use the floor tool. I find it is maybe the most useful 2D/3D hybrid object along with walls, as they display great in 2D and 3D. Also it gives accurate Z heights, unlike extrudes. I use it for everything (well not everything, but certainly extensively)

This really is the rub with ever expanding requirements of CAD apps isn't it. People seem to have an idea that designing a house in 3D is easy, and many seem to think they don't need an architect to do it, except to get them through council. But designing a beautifully detailed house is like designing a car, and yet most would never consider thinking they could build one of those. And for the bog standard house, it is different the world over, which can mess with the usefulness of a PIO.

I find it is that the more we require of our CAD apps, the higher expertise we need to get the results, to the chagrin of many! I love the WinDoor tool by Julian Carr and yet even that took some learning the nonclemature at the beginning.

(What!!! Can't the computer do it for me?!! That is like saying that a person throws a film script in one end and a computer spits a full feature out the other. It ain't going to happen people! ;)

That said PIO's could be much better. I would like to know what Apple would do if it were to design a CAD app. And how far Sketchup Pro will go to bite off the space many other CAD apps sit in now?

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