Experiences using groups or nested families for standard rooms?

[BIM-Lord]

Hi fellow MEP`ers!

We are about to start detailing a hospital project with approximately 7000 rooms.

The architects are aiming at using model-groups for their standard-rooms.  

There has been some talks about trying to use model-groups or nested familys consisting of MEP objects to save some time on coordination.

Project will have about 7 buildings. Im handling plumbing (sanitary, HW,VV,HWC, water-heating, cooling) and mechanical (ventilation).

I assume you know where im headed with this. Im just looking for experiences handling this kind of workflow.

Should we avoid at all cost? Go with some of this some of that?

Worth mentioning that we split models into these three categories piping, fire/sprinkler, mechanical even if they are in the same building. 

Im interested in even the slightest anecdote about anything vaguely related to this.

Thanks for reading 🙂

[iainsavage]

Using groups is a good workflow for repeated room layouts but with a few caveats.

A big advantage, apart from the ease of copying multiple elements at the same time, is that if you edit a group all instances of the group will be changed at the same time so if, say, you had missed out a valve and already made 100 copies - you only need to add the valve to one instance of the group and it will appear in all instances (same as editing a block in Autocad).

Caveats:

• Be careful with hosting of elements and placement of the groups. Face hosted elements will seek a face to attach to and if you don't copy the groups accurately from room to room you might get a warning that elements can't find a host. Make sure rooms are actaully identical rather than similar because differences in length/width of only a few millimetres might lead to host faces not being detected.
• If mirroring groups the above can also be a problem - make sure you mirror about a wall centreline for accurate placement
• Rotating groups might generate a "Can't rotate element into this position" error due to hosting of elements within certain families in the group.
• When connecting pipes etc to the group a fitting (union or transition) will be inserted at the join. Maybe not a big deal but be aware if this upsets your quantities or details. If you don't want this then you would have to ungroup the group before connecting (only do this if you're happy that you no longer require the objects to be grouped cos there's no going back!)
• When pipe/duct sizing the elements in the group will not re-size - you'll need to size these before creating the group or edit them manually after grouping.
• Tags and annotations won't be included in the groups.

These are just my thoughts though. I suggest maybe trying a test sample first before going all in.

It would be good to get other opinions too.