Manual roof questions... and best practices....


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Hi all, in my area I have a lot of odd roof designs with hips, gables, and both, mixed with flat roofs. Most of these are covered porches with all sorts of oddities, that want to become fully closed in rooms, or have additions put on top of them. These were all conventionally framed houses back then.


I have a plan here that is very close to a real job. I got it all to work pretty well overall. It was actually harder to do than the real job because I used the original CA generated roof to start with and it did not have favorable ridges in comparison to the real job. I wound up making custom roof planes for the flat roof and others to tie it all in.


Couple of questions:


  1. I tried to get this to generate using many combinations of wall types on the porch, roof groups, etc., is where any chance this could ever be autogenerated?  Update: I did not try baseline manipulations however.
  2. I got stumped on trying to create roof planes for the gable end of the main ridge. I was thinking of some sort of hip planes to form a ridge, or a (nearly) vertical roof section to form a gable.  I had too much trouble with the thickness, facia, etc. The area is outlined in the attached pics and plan. I wound up using a polyline solid that I left as concrete to make it easily visible.


Any advice is appreciated in advance. Update: I guess it is really a reverse cricket, or a reverse hip? I have done crickets, not sure why my brain can not process this one.



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  • PMMully changed the title to Manual roof questions... and best practices....
22 minutes ago, M-Reed said:

In Texas the roofs built are almost ridiculous in their complexity, height, and sheer size compared to the actual living spaces. This includes multiple pitches as well. That said, I am going to agree to disagree with David on the Auto Generate of every roof first, then edit manually. With a good understanding of geometry a complex roof can actually be modeled faster than the time it takes to edit each exterior wall for roof type, and pitch. After generating an auto roof, many times its so off base that I end up deleting most of it and starting from scratch. 


This is much like the time my two daughters, elementary school age, came home with instructions from their teacher to buy a calculator for them to use in math. These are 2nd and third graders. Of course I objected and went to the school insisting they learn the basics and understanding of why 2+2=4. Then go for the short cuts. 


This applies in most learned things, roof building too. 

I understand the point, sometimes you just gotta cut and run, but you need to know the core well in order to do that. In this case, it was a partial roof-gen, which I used just to see how well the automagical stuff will do and testing the boundaries. It's my way of doing what David preached... fail-fail-succeed. I do the same thing with my golf swing :lol:


One thing I "think" I learned, is the autogen will rarely, if ever, work on these old Florida 50-70's homes that were pre-truss. The ridges and valleys are always completely off. I imagine it was due to what lumber was readily available back then (does anyone balloon frame these days?). When I model the exact specs of this project as-built, I believe I will wind up deleting or modifying every roof plane. To David's point, I might gain a small amount or productivity just by the fact the planes were there in the first place.

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Case in point, this most recent project I did of a 1910 fire damaged house in Gonzales, Texas (West of San Antonio), I did completely manually. It was too complex to try to set up for "auto-roofs". My point is that you do what is necessary to get a project done. The method is NOT important, the result IS.




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Point, counterpoint,...


I went back to the plan, deleted the roof, and started from scratch via auto-gen. The trick I learned just today for the settings was setting the exterior two walls on the porch to "High Shed", and then clicking "Expand Downward" right after. It then generated an excellent rendition of a "modern flat roof", which actually has a small pitch via foam boards under EPDM per our new code. It generated just a slight hip, which is exactly how it would be built.


Since this was an old flat roof, I had to lose the hip and went manual. But it was a snap and turned out well. These old roofs typically have the shingles overlap the EPDM, so I played around with the planes a bit with some success, or may just use a polyline solid to make that connection look better.


Why CA wants two radio buttons, which are normally mutually exclusive to be selected in sequence, to control this is beyond me. But without that sequence the other autogen options were way off outside of starting with hips.


@DavidJPotter so in this instance your motto held :-)

Screenshot 2022-09-14 232820.png

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