Roof that slopes in 2 directions

[jedbjorn]

I am new to Revit and I got it specifically to do a project I think my current program, Chief Architect X8, is not well suited for. I need a tool by tool explanation of how to do this, and it would be greatly appreciated.

We have a "butterfly roof" which is kind of like an inverted gable. It slopes down from the outside at a 4:12, and the resulting valley, which will have to be heat matted, will slope at a perpendicular towards the building edge at a 1:12 in order to drain. I have the butterfly shape, as seen in the attached screen-shot, but I need an accurate downward slope of 1:12 and I don't know how to do that.  I am not familiar enough with families to design this without a little help in the tool department. Also, if it is relevant, I am using Revit LT. Any help you guys can give would be great, thanks. 

[samuelsanf]

You can create a mass modeled like you want and then create a roof from it.

For de mass use a Extrution with the V shape based on a reference plane with the 1:12 slope (from vertical plane, because it's the reference of the section of the roof).

[samuelsanf]

The easy way is make a Floor (not a roof), then create and modify their sub-elemnts to shape it in the way you want.

[ToanDN]

This can be done fairly easily using the system roof tool with added slope
arrow. I can do a screencast video when I get back to the computer.

Other mentioned methods work too.

[jedbjorn]

I'd really appreciate a walk through by video if you can. I have seen on
other threads it can be done with a slope arrow, but when I try to get that
I get an error message, so I am not exactly sure how that goes. I guess
technically it would have a diagonal slope? Not exactly sure how that would
be figured. thanks.

--
Jed Sanford
CAD Draftsman

[samuelsanf]

I tried with slope arrow, but thats doesn't work with roof that have sloped edges.

Another option that could work is making two roof, then merge both with join.

[samuelsanf]

Here how to modify sub elements on Floors.

I don't work with the slope you need, but in South a East (for example) you can draw a detail line temporarily with the slope you want and raise your sub-elements points to match the lines. Or do it matematically.

[samuelsanf]

Here is another method, using roof an Model In-Place:

[samuelsanf · Accepted solution]

And my last workarround, since a roof with sloped edges + slope arrow doesn't work for me, is to make two roof with the two direction slope and combine them.

Please ignore the audio, I forgot to turn it off. Somebody near me hace this audio playing.

[jedbjorn]

Thanks for taking the time to do this! I have Revit LT, and I am thinking it would take the full version to do this. I drew it up wire frame in sketchup right now, and its dead on. I can import sketchup files into Chief Architect, but I would prefer to export a DWG to Revit and then convert it to a roof. Do you have any idea how I would do that? Again, thanks a lot for the thoughts and the time. 

[samuelsanf]

Yes, you can Import a DWG into Revit, convert it to Mass then create a Roof By Mass.

Take a look here:
https://knowledge.autodesk.com/support/revit-products/learn-explore/caas/CloudHelp/cloudhelp/2015/EN...

[samuelsanf]

Any way, I think it's easier if you modeled in by floor wirh subelements or by Model In-Place Roof (like one of my first two Screencast).

[samuelsanf]

*Any way, I think it's easier if you modeled it by floor with sub-elements or by Model In-Place Roof (like one of my first two Screencast).

The two roof method (third Screencast) is more complicated way to obtain a desired slope in both directions.

[Alfredo_Medina · Accepted solution]

Because you work with Revit LT, you need to do it with simple tools. It can be done as shown below, with roof by footprint, starting with a simple rectangle, with a slope arrow from right to left, with a slope of 4/12. Then, rotate the slope arrow clockwise 2.5 degrees. Then, mirror the roof.

[ToanDN]

Here is the screencast.  I use 12 x 12 roof module to simplify the math.

[samuelsanf]

Great video! I didn't do the math, only show the way 

Since the head of Slope Arrow doesn't need to lay on edges of the roof, you can create a roof with any dimension and only draw the slope arrow with the dimenons you show (or similar proportion) 12' with x 3' lenght x 4' 3" height to get the slope we are finding.

[jedbjorn]

It was the math that was tripping me up. I realize that essentially a roof sloping one way at a 4 12 and another way at a 1 12 is actually only one diagonal slope, but my boss needs precision. It took me 15 minutes to get it in sketch up, but having it as a true roof in Revit would be better. Is there any way you could walk me through the math or geometry of it? Might be asking a lot. Is there a formula for it?

[jedbjorn]

Samuel is right, I just tried it. It maintains its proper pitch when stretched. Just leave the arrow on its grid. I really want to know the math you did to figure that toanD, that was awesome

[ToanDN]

It is quite simple:

- Slope in X axis = 4

- Slope in Y axis = 1

- True diagonal slope vector tail coordinate = 0, head coordinate = 4 units in X axis and 1 unit in Y axis, or  12' and 3' respectively, as I draw.

- The raise at the head of the slope arrow = 4' (from 4:12 of 12' run) + 3" (from 1:12 of 3' run) = 4'-3".

[jedbjorn]

I know, I got it a few minutes after I asked. Thanks A LOT man. I got this
job now because of the complexity of this project. My boss had been using a
2D guy, but he needed this modeled. You really are making me look good
here! Thanks to Samual too for all his work and for his insight that as
long as the arrow stays, the roof can be any size, so the math stays the
same. You guys are great.

--
Jed Sanford