Roof by foor print with defined slope wrong geometry?

[Anonymous]

Hi,

I want to create flat roof with slope (1:50) defined by slope edges (edges around gutter area marked in blue clouds below) . It does it quite well aside one place where the slope is not toward outlet but the wall (marked in yellow). From what knowledge I have from geometry standpoint you could just extend the edges (along red lines drawn below)to get rid of the slope toward the wall and by vertical adjustment still keep 1:50 slope. Alas - there's no way of editing this way roof I've created and I would like not use subelement editing as it is very tedious if you want to keep constant slope everywhere. Can anyone tell me why Revit does it? Obviously with steeper slope thing is resolved as is with additional gutter but it is geometrically possible with current setup so why Revit makes it impossible? Am I missing something here?

[ToanDN]

Before getting into solving what you have, normally for such gently slope, we use a true flat roof and modify subelements to add points snd crickets, same as if it would be built: flat structure with sloped insulation.

[Anonymous]

I do agree but problem with subelements is that creating a set slope is a guesswork really if you haven't done your drafting and calculations the old school way (which is silly taking into account that it should be fairly easy to do it with computers and is mostly done). Not to mention it's hardly possible to avoid triangulation of faces. I'd love for the sloped roof to let us use varied thickness of selected layers as with subelements modification unfortunately for reasons unknown to me it is not possible. But I can accept lack of varied thickness for the sake of proper surface topology of such roof.

[barthbradley]

...your roof dilemma reminds me of Penrose Stairs. hehe.  

[tino.freitas]

Hi @Anonymous,

It seems like you are having a problem with your roof. Can you please reply to the following questions:

• What version of Revit are you using?
• Is it fully updated?
• Can you share your file with us so we can try to reproduce it in our system?

[Anonymous]

Hi Tino,

Thanks for looking into it. I'm attaching the roof in this post. As to your questions - here is info about my build: 

I don't know if it has the latest update as I am not taking care for such things but I'd assume it should be pretty up to date.

I don't have the feeling that Revit has done something wrong here rather that's the way it works. What worries me is that the automatic roof option does totally ignore any holes in the roof thus also creating a geometry that wouldn't be working properly.

[tino.freitas]

Hi @Anonymous

thank you for sharing the files with us. We will try to reproduce the issue on our system and we will let you know if we have the same results. As for your Revit version it seems to be the last update. We will keep you posted.

[Anonymous]

Hi Tino, 

Any luck finding the reason why Revit doesn't do the job right?

[tino.freitas]

Hi @Anonymous 

We are still looking into it. We are hoping to give you an answer tomorrow.

[tino.freitas · Accepted solution]

Hi @Anonymous 

one of our developers has taken a look at your roof and we have come up with a solution for you. It seems the issue is related to very small portions of a roof determining the slope over large swaths and can be resolved by splitting the roof at the offending ridge or valley as you can see from image below:

this may not be ideal but it takes little time and all you have to do is copy/paste aligned to the same place and edit the sketches on both roofs.

[barthbradley]

@tino.freitas: I'd love to examine your RVT. Could you possibly share it?

[Anonymous]

Hi Tino,

Thanks for your time you took to look into it. It looks like my assumptions that Revit didn't handle it properly were correct - is there a way to convey this to Revit team to fix it? This roof isn't especially complex and this shows that you cannot rely on this tool to produce a roof without checking it. I'm also wondering why Revit ignores the openings withing roof while creating the geometry?

Generally your method is a workaround for one problem I have here but there's more to it. 

[tino.freitas]

Hi @Anonymous 

can you let us know if you have tried the suggestion on previous post? If you could also send us a sketch of what the intent of the roof is, perhaps we can help you with a different solution.

[Anonymous]

Hi Tino,

The problem with slope going wrong way is solved by dividing the roof but it's a pity that Revit doesn't do the original job properly. Nonetheless I thank you for helping.

My other question was referring to the fact that Revit ignores the openings in the roof (marked in yellow previously) and generates slopes as if the openings were not there.

[Anonymous]

I tried to make roof in other place and you really can't go much simpler than that and Revit really goes wild here. Escher's reference before makes here even more sense as I can't process what I see... It plainly shows that roof tool hasn't been really tested and fails the most simple tasks. But please do tell me that I miss something obious here (file attached).

[Anonymous]

Ok, here is another example of how using roof by footprint doesn't do the job (or again, I don't know how to do it properly). Edges marked in red define the slope. Thing worth mentioning that this is a roof surrounded by parapet wall (as previous were) - which should give some idea why this is such a problem for me. But I shouldn't even think it might be a problem because I selected which edges are to define slopes, right? And what I'd assume is that end point for all slopes should be on the red edges. Unfortunately I think Revit assumes it is a simple roof and no matter what it sets slope to a long parapet wall (marked in yellow below). So either I have too high expectations for this tool or it is simply not the tool for the job and I have to use subelement modifications (which won't give me exactly the right slopes I need).

[tino.freitas]

Hi @Anonymous

I will check with the development team on your latest posts and we will inform you if there are workarounds or if it's something we need to improve on.

[Anonymous]

Hi Tino,

Thank you very much for looking into it. Currently as I couldn't wait no more I simply had to take a few steps back and simply calculate everything by hand and use subelements modifications setting everything out as in the old days because relying on automatic roof generator proved to failed me too often and conversion from automatic roof to subelement-able roof is not an option (maybe a thing to think about as it is possible with stairs to convert). So using my geometry knowledge I managed to create roof as I wanted it but Revit helped me very little with it. There were places where automatic roofs gave me a hint but I had to create small portions as with larger and more complicated areas it simply didn't work. I see a lot of room for improvement in Revit's roof department . 

[tino.freitas]

Hi @Anonymous 

according the information we have from our developers it is not recommended to have small segments of roof defining the slope for a large area since this may cause inaccuracies of this type.

Please take a look at how your second roof example was resolved by our team:

Let us know if this helps you resolve this issue and if you need any more help.