Alternative to Model Groups?

[andipiper]

Hi all

My office works on a lot of multi-family residential projects that include as many as 20 unit types. We recently migrated to Revit so we are still figuring out our own best practices.

So far, we have been using model groups to create our unit types. However, these have a tendency to break or cause error unexpectedly. It's been very difficult to manage. I have seen some people suggest linking a model for each unit type, but having to open a separate file any time we have to edit a unit is not ideal (especially with clients who like to make changes late in the game).

Has anyone found a useful alternative or a way to make Model Groups work more consistently? All advice welcome.

Thanks!

[Steve_Stafford]

Groups are the tool intended for this.

Face-Based elements don't work well in groups however. If this is your primary kind of work then it will help to make sure the content you use is not face-based but "level based" or "not hosted" as some people refer to them. Everything in Revit is hosted but level based families just reference a Level (think story/floor) like things do in real life.

Also while walls can be constrained to levels, base and top groups should not be attempting to stretch (change) where floor to floor varies but the unit is the "same". Generally the unit walls should be "unconstrained", set to a specific height to avoid group warnings. It may be the same plan but technically a floor with a different floor to floor height is "different enough" for Revit to see a difference.

Also look for logical separation between the shell/core of the building and what defines a unit. For example, corridor and exterior walls could/should be separate from the units. A unit can include a demising wall or each unit can...or they can each have "half" a wall. Where each unit has both demising walls on either side you can "Exclude" one of them from the group to avoid wall's overlapping warnings.

It is a bit of an artform...but multi-family unit design and assemble is too.

[andipiper]

Thanks for the tips!

When you say Face-Based does that include wall, floor and ceiling based? Our light fixtures are all ceiling based, it wouldn't be ideal to un-host them (though certainly do-able).

We have been using unconstrained wall heights so far but I'll make sure it's on our standards list now that I know it's a factor.

Still finding the perfect strategy for separating "unit" walls from "building" walls, but I think we are getting there.

Thanks!

[Steve_Stafford]

"XXX-Base" requires "that" host (wall, ceiling etc) to be in the group too. The hosted element can't be in a group without the host. Face-based families don't care what the element is that hosts it, it just has to be a "face"...wall, floor, desk, window, glass...etc. Face-based families fail when mirroring is used or when they are rotated (might fail). Mirrored conditions should be separate units for the greatest "stability".

[andipiper]

So ceiling based should be fine as long as the host ceiling is in the group?

[Steve_Stafford]

Yes that should be fine.

[andipiper]

Awesome. Thanks so much for your help!

[Steve_Stafford]

Keep in mind that the Automatic Ceiling option (versus Sketch Ceiling) will create a "relationship" between walls. It may be safer to use Sketch if any of the boundary walls are not going to be part of the group too.