Revit: Model Groups Best Practices

Model Groups are a great tool to quickly layout components that repeat throughout the Revit model. However, misused of this tool can result in many model errors, delays and loss of work.

To minimize errors caused by groups, follow these guidelines for best practices:

• Use model groups sparingly as needed. An overloaded model with groups may experience reduced model performance and slowness.

• Use the kit of parts approach when creating groups. For example, an Apartment Unit would have the following independent groups:

  • Unit walls and doors, room separation lines (no rooms or rooms tags).

  • Unit ceilings, lights, and other ceiling elements (be sure no family is hosted to a wall or surface that is not part of the group, such families should be level hosted).

  • Bathroom and kitchen families.

  • Furniture (be sure no family is hosted to a wall or surface that is not part of the group, such families should be level hosted).

  • Area Lines (not areas). Do not use area groups for different area schemes.

• Be consistent when naming groups, keep an organized and easy to identify system.

  • Example: Unit 2A_Ceilings & Fixtures, Unit 2A_Interior wall & doors

• Remember to set walls to unconnected if they are part of the group. If the top constraint is set to a specific level, when you copy that group or if you move the level, it may result in “fix group” warning. You can use the attach to/base tool when instances are needed.

• Avoid constraining elements in a group to objects in the model.

• Verify that all elements within the group are hosted or constrained to the same level.

• DO NOT HOST GROUPS WITHIN GROUPS. This will likely result in the error to “ungroup” or “fix” the group.

• If you want to attach 2D detail groups to 3D groups, keep it a consistent naming convention and limit to only one per group.

• When adding a hosted element into the group, the host and all hosted elements also need to be part of that group.

  • Example: to add a door to a group, you must also add the wall.

• If a warning is prompted asking to “fix the groups”, cancel the command. Choosing to fix the group option does not fix the group. It creates a new group that is no longer referenced to the original group. Unfortunately, there is no way around this, this is the likely error if one of the steps above was not followed properly. The choice to create a new group or to ungroup will need to be made. If the project is closer to completing construction documents, consider ungrouping, if not, creating a new group may be the right step and replace the old groups to avoid future errors. Sometimes copying the group to clipboard and pasting to align view works (fingers crossed).

• Edit Groups in the phase they are used in, if placed in multiple phases, edit in the earliest phase it is used in.

Avoid the following:

• Do not mirror groups, it is best to copy a group and use a consistent insertion point. Placing a new group is also a good option, it typically follows the position of the original group. You can also drag and drop from the project browser under the group category. If necessary, create a right and left version of the group for proper positioning.  

• Try avoiding using the “exclude element” as this can result in confusing behavior or handling of the group, specially as the project progresses and new team member may be involved. 

• Try to keep all elements inside the group within the same workset if possible (must be done before becoming a group).

What not to include in model groups:

• Demising, corridor and core walls, circulation (elevators, stairs). Use Reference planes to align and lock and coordinate the placement of these elements..

• If working in a building typology with repeated floors, such as an Apartment building or a Hotel, do not include the entry doors, use Reference Planes.

• Façade elements - these elements should be coordinated using reference planes.

• Rooms and tags. (Note: when grouping rooms, the room name does not change per group instance, but the room number varies, avoid rooms in groups, if possible).

• Areas and tags.

• Datum elements such as levels, grids, reference planes and scope boxes.

• In-place families.

Our final thoughts are; plan ahead, discuss the project needs with the BIM lead (if available) and document the project model groups set up. Following these steps and guidelines can help reduce errors and maintain better model performance.