Wall best practices.

[dennisng]

Hi All,

I'm new here and have been using revit for about 2 years now. I'm still having trouble understanding and creating wall types for exterior walls. Let me explain.

Exterior walls are made up, if you will, of the structure (drywall, 2x6 studs, insulation and sheathing) and the finish (EIFS, board and batten). I've tried building a wall with both the structure and the finish together, and modelling a 2 storey building where the wall would run from foundation to top of parapet. At times, if i have a material change say in the middle of the wall, it becomes problematic.

I've also tried building the "structure" (drywall, 2x6 studs, insulation and sheathing) from floor to floor and applying the finish from foundation to top of parapet and if there are any material changes i can cut out the finish and replace with new material without interupting the basic frame structure. But the problem with this method is if the building expands or contracts I would have to go around and change each wall. I makes it more cumbersom and I believe it doesn't exploit the power of a BIM 3D modeler. I might be doing something wrong here though (not constraining walls or should be building structure from foundation to top of parapet, etc)

Can I get a best practice or experience from others on how to tackle this issue? I basically construct the model as though I was physically "building" the building, i may be wrong though.

I welcome other peoples opinions on this.

Cheers,
Dennis.

[Revitaoist]

Are you doing the material change in the structure of the wall, or manually changing it in the project environment? There's a few tricks to change the behavior of walls when you're in the edit structure: change the preview to section, modify, unlock the finish layer, so you can adjust it separate from the structure, and split the finish layers to apply different materials at different heights.

[Norton_cad]

Do it separately. Model the wall excluding the framing, and do the framing separately as a railing/framing. You have to associate the swept path manually to the slab though, via a locked dimension. Very BIM I think. Also doing the framing separately means you can associate it to any slab perimtre beam soffit and/or bund upstands.

[jbayne]

Just to be clear.

We have a CMU wall from footing to a parapet that slopes two feet above roof. On the interior side we have different conditions of gypsum board (from 6" stud in some areas and 7/8" furring in others).
Should we put in the CMU as one component so that it can be one slope and then put in Gyp Bd as another to the height and type it needs to be?
What about openings in the wall does this cause issues with that?

[david_peterson]

Hi Jim,
As a person that works on the structural side, I can give you my answer. CMU wall should ALWAYS be separated from everything else. If you are working with a structural consultant this is kind of a required practice. Generally speaking, when it comes to CMU walls, they should always show up on the structural drawings so the contractor knows where the dowels need to go. But at the same time we don't like to clutter our drawings to show every partition wall that's there. Since you can't separate them via V/G or any other way, structurally we'd have to trace all of your cmu wall and adjust them every time they move. If you set all of the CMU walls to bearing and have them separated from the gyp and studs and such, I can link in your model and set the discipline to structural and any wall that you have set to bearing will show up. This way you have total control over where you walls are located.
Now this would be a different story if you're talking about load bearing cmu structures. In that case it's a little more difficult. I've done them both ways. While I don't like to do it, in one case Structural owned the cmu walls, and was responsible for them. This was a very difficult and challenging task trying to keep up with the Archies. On the next project, the Archies owned the walls, and we simply showed their locations and relationships to the rest of the structural framing. There the problem was the archies forgot that once our structural drawings went out the door, that they couldn't change anything. But they did anyway and it was kind of a cluster.
Just my 2 cents.

[jbayne]

Dave,
Thank you for the reply that is helpful. We are in a unique situation where we have all disciplines in house and we will all be using the same model with worksets handling the ownership of items.

We are trying to move from Microstation to Revit. That, by itself, is daunting and then any issues like sloping walls when there are different wall types causes concerns.
If we model the two components (CMU and interior finish) separately how do we handle the openings in the walls (doors, windows) do we have to create opening in finish wall manually?
If we have different wall types going up to and attaching to sloped roof can we still modify interior finishes by keeping the finishes unlocked in the wall creator?

We are just starting out in this so any and all help is appreciated.

[david_peterson]

Hi Jim
That's kind of the kicker. Multiple walls = multiple openings. I know it sounds like more work, but in the end it depends on what you want your drawings to look like.
Our Archies work just 2 cubes down, but we always have separate structural drawings.
If you turn on all the walls and doors and windows and such, our drawings get very cluttered.
We have yet to be able to work all in one model (project & file size hinders the process) but even if we did, I'd still tell them to separate them. By separating them it gives you the flexibility to do what every you want to each wall individually. So I would tend to say that the window or door gets assigned to the finish and the opening goes in the CMU wall. Reason is that you can always an "Air Space" layer to the finish wall so your door and window jabs with pass through. I would also tend to use the "Door Opening" family. which I believe is a door with now panel or jamb. But allows you to match the RO for the window or door with one object vs trying to just drag a generic wall opening.
For that matter, studs would be the same way. Think of it this way, model it how its going to get built. If you're studs stop at the floor slab but the cladding continue past, you may not want to model them in the same wall. A lot of this also comes down to detailing. If you are trying to use your model for the details, you'll spend more time making the model perfect. If you're not, then you can make the detail perfect. It's a really fine line. But as a general practice, if one component of your wall need to stop or be interrupted, you'll have to model that as separated. As far as I know you can't get different components (layers) of your wall to stop at different elevations. So you can either model it correctly and try to use the model for your details and overall sections, or you can try to model it down and dirty and turn the model off in your sections. But if you go with option 2, you're kind of taking the usefulness out of revit.
Again I'm on the structural side, so that's what I look out for. To be honest, I tend to model everything that's in the model, but I use drafting views for most of my details due to how much stuff I would need to modify. ie there's not need to model copes and connections, but gusset plates need to be modeled to avoid conflicts. I also tend to cut duplicate "Coordination" sections to check my model against the archies model. So I'm still in the stone age when it comes to detailing in revit. But what kills me is when my archies tell me that they can't see something that should be there and I know is there, only to find out that they've hidden the objects or my model entirely.

[JohnCAVogt]

Re the duplicated openings: in limited cases, smaller buildings, I suppose, you can sometimes take advantage of joining the geometry of parallel walls and they take on the same cut opening from windows and doors.