Forums >> Community >> Newbies >> New Member-flat/sloped roof problems.

JsBach

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Joined: Wed, Jul 1, 2009
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 Hello All,

 I am new to Revit and these forums. I have decided to teach myself Revit during my unemployment. So far I have been able to figure out most things or find workarounds. One big problem I am having is with a flat roof. We all know that the roof isn't really flat, it has to slope for drainage. The built-up roofs I have done slope 1/4" per foot. This is achieved by sloping the underlying structure, with decking, insulation, and coverboard as needed all laying on sloped joists.

 I am able to get that far but I am having trouble when I try and slope the roof to drains. There is an option to modify sub elements when you draw the roof totally flat, but that option goes away when the roof slopes with the structue. From what I know, this additional sloping is achieved by building additional layers of insulation as required. Revit is not letting me do this when the roof has a built in slope to it. Hopefully most of you will understand the dilema.

 I have thought of just modeling the basic roof and adding detail lines on the roof plan to indicate the built up layers, but when I go to do spot elevations these seem to be unchangable and only read what the model is showing. I have also thought about building up seperate masses of insulation but this seems difficult and a work around as well.

 So has anyone else encountered this pretty common way of building a roof and what have you done to resolve this in Revit.

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Mr Spot

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Joined: Mon, Jan 12, 2004
2889 Posts

If you could provide a sketch section through the roof I would be clearer on what you are after. But it sounds like what you want is the soffit of the roof is on a slope to match your rafters and then the decking has a different slope to floors.

This could be achieved with 2 overlapping roofs and joining geometry.  The base roof would not have a variable layer (then use modify sub-elements to get the required slope) and the top roof would only have the required variable layer to achieve the slopes to drainage.

I hope I'm understanding what you want correctly.  If not let me know...

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Chris.

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JsBach

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Joined: Wed, Jul 1, 2009
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 Thanks for the reply Mr. Spot. I am attaching some sketches of the building in question. The 3D drawing barely indicates the slope from front to back of 1/4" per foot and also shows the roof scuppers/drains. The section shows how the whole roof slopes. The roof plan shows the lines of where I would like to build up insulaion to taper water to the drains. Again, if the roof was flat, you can use the modify roof tools to add split lines and raise specific points. This whole series of commands does not come up with the sloping roof.

  Almost every commercial or retail building I have done has been a variation on this type of roof, surely Revit must have a simple solution.

 Thanks

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Mr Spot

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Joined: Mon, Jan 12, 2004
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Apologies for the delay.  I've had difficult accessing RevitCity during the upgrade.

Similar to my first thoughts I'd model them as two roofs and then join geometry.

1 Roof is the whole roof at the main slope.  The other is the remaining triangles with the modified sub elements.  Its structure would only be the decking and insulation...

HTH.

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

Regards,

Chris.

Co-Founder | BIM Consultant | Software Designer  B. Arch)

Xrev Revit API Addins | Revit Rants

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