Variable Layer Thickness - Down instead of Up

[Brockway]

Is it possible to set one of the lower layers of the structure of a slab to variable then utilize sub-elements to adjust the shape and maintain a level upper plane?

[patricks]

Go to the floor's assembly dialog and check which layers are set to "variable" on the far right.

[Brockway]

Yes, I did that. I made the lowest layer variable but when I modify sub-elements I see the shape modifications in the upper most layer. I want the shape to be variable down and show a truly level layer at the upper most layer. Like the above attached jpg.

[patricks]

Can you isolate out that element and post a small Revit file?

[Brockway]

Well...hmmm. I don't think I'm asking this question properly.

Let me try again.

When editing slab sub-elements, it seems that the sub-elements are always placed from the top face. Therefore, one could have a flat/level bottom face of slab but could never have a flat/level top face of slab. I wish to have a slab object that has a flat/level top face and a variable/pitched/tapered bottom face. Think of it as if I were to take a level metal deck with tapered insulation and EPDM assembly and turned it upside down.

I've attached a slab element where I've bent it around a bit with sub-elements and attempted to make the portions variable that would be but since the sub-element adjustment plain is at the top, it doesn't do what I want.

[patricks]

I see what you're saying now. I'm not sure how to make that happen, actually.

[alessandro.m]

I'm looking at exactly the same issue at the minute. I don't have a solution so make sure it gets posted if you do find one!

[cliff collins]

Use the "turn gravity upside down tool"?

Seriously, why would we want to have a slab sloping on the bottom side?

I suppose you could create a Mass and convert it to a floor?

Or model in-place family?

The "host" slabs are made to slope from the "top" face, to provide gravity-drainage, etc.

cheers.......

[Brockway]

OH! I know that button. It's right next to my "VE" button which is similar to the "Panic" button.
Well, I realize that I could play the Mass game or the In Place Family game but the sub-elements seem pretty intuitive and and easy to manipulate. So, I was hoping to use them to create some canopy shapes in the -Z direction then use a seperate slab to create some different shapes in the +Z direction: join the two slabs together and you get a graphic that looks decent. I'll just stick to what I'm doing by having a thin slab that's not variable at the top and bottom and air between.

[alessandro.m]

In my case I have some horse shoe shaped balconies looking onto a courtyard. Each of the balconies tapers from 325mm thk to 200mm thk at their tip.

With the complex profile of the balcony it would be much easier if I could just adjust the offset of the lower plane of the balcony slab to create the profile. I ran through the process tapering the upper surface of the slab and it was very straightforward. I was hoping it would be just as easy to taper the underside!

[cliff collins]

OK,

Some real-world applications of upside-down sloping slabs!

Sounds like a Wishlist item....

perhaps one of you good chaps could place a wishlist request......


cheers......

[wmullett]

Why not just use a void sweep along the edge of the slab to create this bottom slope?

[patricks]

Why not just use a void sweep along the edge of the slab to create this bottom slope?

Then it would not have the bottom layer sloping while maintaining thickness and the middle layer having variable thickness in section.

[wmullett]

With the void sweep everything will look correct in 3D views and elevations. You would only need to show the layer changes in a sectional viw and that is what the edit cut profile tool is meant to be used for.

[alessandro.m]

In my case the width of the section I'm trying to get to taper varies so I don't think the void sweep would work quite so well - I want to maintain the depth of the slab along each edge. I've attached an image to explain the profile. Is just a bit annoying that to create exactly the same form inverted is very straightforward but becomes more of an issue when the other way up!