Can Not Add Sloe to Floor with Slope Arrow

[turner756103]

I need to be able to apply a consistent slope (1/4" per foot) to a floor assembly with a complex shape in plan. I am able to accomplish this by modifying sub-elements and manually setting the elevation of each point around the edge of the floor. I should be able to achieve the same goal - in much less time - using a slope arrow, but have not been able to do so. Ideally, the bottom of the floor would remain flat.

I am designing sloped crickets for a drainage system over a sub-grade concrete roof slab. Each section of sloped cricket is modeled as a floor type. The assembly of this floor type is a single layer of polyurethane foam with variable thickness (min. 1-3/4"). When I try to add a 1/4" per foot positive slope to the roof crickets using a slope arrow, I receive this mystifying error (mystifying because what else would you want to do with a slope arrow other than make something NOT be horizontal?):

"Slab Shape Edit failed. The Roof or Floor is no longer horizontal."

The base thickness of the floor is 1-3/4" and I am trying to add a positive slope of 1/4" per foot (away from through-slab drains). After I have attempted to apply the slope arrow, when the error message pops up, I can zoom in and see that the correct slope has been applied (the edge of the cricket lines up with adjacent elements which have been sloped using another, more tedious method), so I know that it is attempting to behave as I have intended.

I can also see that the bottom of the floor has been sloped, which is not intended. I am confused about why this is happening, as I have checked the 'variable' box for the relevant layer of the floor assembly in the 'Edit Type > Structure: Edit' dialogue. My understanding is that, when there is a variable layer in the floor assembly, the bottom will remain flat when a slope is applied and the change in thickness will happen in that layer. But, even if that is not the case, I still don't understand why Revit throws an error when I try to add this gentle slope to the cricket. I could live with a slope on the bottom of the cricket if I needed to.

Things I have tried:

• Adding an additional, non-variable layer to the floor type assembly
• Increasing the overall thickness of the floor to something well in excess of the total change in thickness
• Changing the Function from Exterior to Interior (I'm flailing here, I don't know what else to try)
• Reviewing knowledge.autodesk which says that you should only be getting this error if you are trying to apply a slope arrow which would result in a less-than-zero thickness floor (which I am not, thanks for nothing Autodesk)

In the end, I have never gotten the crickets to slope correctly using slope arrows, and have had to go in and modify the elevation at each point around the boundary of the cricket - point-by-point, in elevation, snapping them to a model line with the correct slope. This method, while exact, is obviously incredibly tedious and must be redone from scratch every time that I make a minor edit to the shape of one of the crickets. It is far from an ideal method. We need the exact slope modeled so that the height of the crickets can be called out with elevation markers at various points for coordination with the landscape design. I've been muddling along with the current approach for the past few months, but it is incredibly time consuming to reset all of the vertices of a roof cricket each time that I need to make a minor edit, such as shifting the location of stub wall, etc. Being able to do this with slope arrows would save me a lot of time and effort and seems like the natural way to achieve this particular goal (it's just a simple slope! This is not complicated!).

Am I doing it wrong? Is what I want to do impossible? is there another (less time-consuming) way to achieve the same results? Is there another method for modeling sloped drainage crickets that I haven't considered? Anything that means I can stop using my current, time consuming method would be a solution to this issue.

Shape Edit Failed.png

Floor Assembly.png

[Steve_Stafford]

Sorry, Slope Arrow and Boundary Edges that are Define Slope do not work with the Variable layer setting within the floor types. Shape Editing is only possible when the floor slab is flat and the shape nodes are adjusted to define the slope.

Since you're focused on crickets you might consider another approach, visit Brian Mackey's blog post on them.