Wall Functions

[Sweetshelby]

I have read the help on the wall layer function but I was wondering what people do when they have 2 structure components in one wall, say like double studs. We use a lot of these types of walls and seem to be having more and more issues with wall cleanups because of them.

See image

Here is one of the wall types we have. What would anyone recommend doing for this issue with a double structure. Right now we have them both inside the core boundaries but I dont know if this is the best way.

Would we be better off only having one structure and making the other one substrate?

Thank for any advice!

[patricks]

hmm for that particular type that you attached in the image, I would say that you should make whatever component if the STRUCTURAL bearing component of the wall be in the core. I'm guessing it's probably the masonry. I'm guessing the studs are probably just furring inside the masonry. If so then put that ouside the core.

If it is furring, however, you might consider doing the furring as a separate wall, since in essence it is actually a separate wall when it's built.

[Sweetshelby]

So do you think having the 2 structural components is not how the developers intended the walls to be used? And this is why we are having so many issues.

Would you recommend only having one say structure (inside core) and the other say substrate?

[neb1998]

Can you post a screenshot (image) of the cleanup problem? I use this type of wall and dont seem to have any cleanup problems.

[Melarch]

There are several ways to handle wall types with multiple structural layers between the core boundaries.

The first question is what structural or bearing purpose the dual layers of structurally assigned materials have in the walls construction and bearing for other building elements such as floors and roofs. If the two materail layers do not serve to provide bearing for these other building elements than they should not be included between the core boundaries in the first place. Example: You Wall Type construction shows CMU and metal stud as the material layers between the core boundaries implying that both contribute to the support of other building elements such as floors and roofs. Do they in fact or is just the CMU layer providing structural/bearing for these building elements.

A good way to understand this bearing issue is to decide if the wall is a bearing wall in the first place and structural used (in the Element Properties for the Wall Type is Bearing/Shearor structural combined selected under Structural>Structural Usage. If not then the engineer or architect has not deemed this a structural wall and it will not display as a structural element or schedule as such either.

Not withstanding the dualality of the two material layers in this Wall Type are not both subject to supporting floors or roofs. A case where two material layers in a wall type are acting in combination to support the supporting buidling elements is two layers of CMU or two layers of studs. Multiple layers of studs or masonry are often used to create structural fire breaks between spaces requirig different fire rated wall types such as corridors to elevators or mechanical rooms. But often in these fire separations conditions only one of the material wall layers is acting as a support or bearing wall.

In answer to the real question at hand, should there be two or more structural material layers between the core boundaries, probably not for many reasons then I referred to above. Placing multiple layers between the core boundary layers makes it more difficult to clean up wall connections, but not impossible. Several tools to learn to use are "Edit Wall Joins" and "Edit Cut Profile" and "Cut Geometry" on the Tool bar. Another method of managing better wall cleanup conditions is if you have to plae multiple material layers between the core boundary, but one is not really a supporting element, make one of the material layers a finish 4 or 5 priority layer this will hel with the cleanup. Also, Splitting the intersecting or "T" wall where two walls meet will enable more options or conditions when using the "Edit Wall Join" tool.

Mel Persin, AIA

[kpaxton]

The CMU and studs are for fire ratings and sound attenuation only. So what do you put inside the "core"? Would you do any structure in the wall at all? NOTE: You can't have 'nothing' in the Core layer. Revit will give you an error saying if it's zero thickness, it has to be a membrane layer. IF you change the core to a membrane... it gives you an error that the core can't be a membrane. SIGH. :banghead:

My suggestion is that if you're using masonry, or studs for infil, go ahead and make them part of the core of a different wall type. Place your wall with the justification as necessary (centerline, face of core, face of finish, etc). Make all of your joins of these which are next to your frame as Butt-joints. Cycle through as required to get the look you need.

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I do have to agree with the statements that Mel has mentioned (above) and I may end up reiterating a lot of what he's already said. I almost have to wonder, however, if this is complicating matters a bit more than they need to be. We have a tendency (in Revit) to take the most simplistic aspects and make them difficult. :D

As I look at your example, there are a few things that stand out to me. The first is what is this wall? Is it a structural masonry wall with an internal metal furring layer? Or is it a structural stud wall that will be behind and supporting masonry? (which is not typical..) WHY would you have both of these elements as the structure?

If it is the masonry that is indeed the structural aspect (and what the structural engineer is going to base his calcs on), then that is your 'Structure [1]' layer. Everything else is added to after and incidental to this. Think about how this wall is to be built in the "Real World". Can you build the masonry and have it sit there without anything else? Then this is your Core.

The other materials and aspects get added to, and outside of, this core; The "Finish 1 [4]" layer, (3/4" stucco) at the exterior is in the correct position. Elements on lines 4, 5 & 6 however, should be moved down to be outside the Core. Again, these are incidental to the main structure of the wall.

I have to ask why is there a "Substrate [2]" layer (finishes-interior ?) between the stud and masonry?? Typically (and I'm speaking of North American construction) there isn't one, unless... the masonry is not the structure... and the 6" metal stud IS. The structure would then transfer to the stud layer and the others are veneers.

Now, to your question if there is a double stud layer wall (party walls, tenant separations, etc.) Certainly we've done this two ways, but you'll have to decide which way works best. The simplistic way is to calculate the entire structural cavity including airspaces, and make the 'stud layer' that dimension. It's very clean in plan and you'll have to add detailing to the sections, etc. The other is to actually add the two as separate core structural stud layers (as you've done) and go from there. These will then show up as separate items in plan and in section. They do cause some wall-join headaches.

Keep in mind: It is my understanding that the separate layers that Revit defines in the walls (core [1], substrate [2], thermals [3], finish [4] & [5] ) are not just listed like that for our convenience. These numbers actually help the algorithm engine when it's doing the clean-ups at the wall joins. When you start placing multiple items in these categories, they could cause a few headaches and mishaps. I'm not saying all the time.. but they do occur. To get around that, we calculate what the entire wall thickness would be, generate our wall type, then make one wall type that is half of this thickness. Since this is typically on a gridline or centerline (between units), it makes great sense. We just draw the wall down that line, then draw up the other side, and join geometry to make the 'joint' line disappear.

I can't speak as to the 'bearing or not bearing' toggle in the Properties. We currently don't use this and haven't run into any problems not using it. As we become more involved and if any of our structural engineers use Revit, this will probably become more and more important.

I hope I didn't muddy the waters any more than they already were ;)

Kyle

[Sweetshelby]

No what you said really helped thank you so much. The guy working on the project will be glad to hear it. He almost pulled all his hair out the other day trying to cleanup walls. The project he is working on is a Large custom home and he said the stud is the structure and the cmu is only for the stucco. I thinking setting the stud to be the only structure (1) will really help.

As for party walls I tend to lean more toward the one wall for each side. We have also done both but but never found one to work better than the other. About 80% of our work is Timeshares or Condos so we use Party walls a lot. Thank again for the great advice! I know it will help us and hopefully it can help many other!