Join Paul F. Aubin for an in-depth discussion in this video Understanding families, groups, and blocks, part of Migrating from AutoCAD to Revit.
Nearly all graphic software has some methods to take a collection of primitive objects and assemble them into a meaningful object that we wish to reuse across one or more projects. Such items go by various names, we've got Symbols or References, Collections, Blocks or Groups, and many others. In AutoCAD, we have Blocks. In Revit, the closest equivalent to a Block would be either a Family or a Group, but neither is completely synonymous. So, what I'd like to do here is kind of talk about what the differences are between Families and Groups and kind of equate those as best as I can to how they may or may not match up to the functionality you're used to with Blocks in AutoCAD.
So, I'm in a file here called Families, and it is a version of our Condo Plan that we've seen before, but, as you can see, it's been expanded a little to include four units. I'm going to zoom in over here in this Utility room area, and let's start with some really basic notions. If you are working in AutoCAD and drawing a similar plan like this, when it came time to add the door or the hot water heater or the furnace, you'd add those items typically with the Block, because, you would not want to draw all the individual lines in the art to make up the door and then draw it again and again.
For other instances, you'd simply draw it once, and then use that Block over and over again. And some of the advantages you'd gain from doing it that way would be that later if you decided to make a change to that door block, you could update that change, and it would update across the project. And we could actually do the same thing here with the Family. So, if I'd have opened this Family and make a change to the single flush door family, that change would actually propagate throughout the project here and all single flush doors would update. So, in that respect, there is a similarity between Families and Blocks.
And we have some other examples here, we've got a Hot Water Heater, this is also a Family. We've got this Furnace here, this is also a Family. Another similarity we have here is the blocks are often stored externally to the project up on a network server somewhere. We will see the same kind of strategy being employed with Family. So, you would probably go out to a network server to find this Hot Water Heater and the Furnace and the Wash Room and the Dryer. So, those are the similarities. However, in Revit, Families are much more fundamental to the structure of the program.
So, in the previous movie we talked about Categories and those being the fundamental characteristic that defines the behavior of each object. Well, Category by itself isn't enough to define that behavior. The behavior is actually a multistep hierarchical relationship and what we find is that each category in Revit actually is broken down into one or more Families. So, Families aren't limited to just these things that are convenient to place as single objects.
Every element in Revit is part of a Family. So, if I select this wall right here, what we see is Basic Wall is the name of the Family. And if I select the door, Single Flush is the name of the Family. There is no difference as far as Revit's concerned, between having a family that defines this door and having a family that defines this wall. If I select this stair element over here, Stair is the name of the Family. If I select this floor slab over here, Floor is the name of the Family.
In other words, every element in Revit is part of a Family. This is not the case in AutoCAD. When you draw walls or floors or stairs in AutoCAD, typically those items are drawn from a collection of individual lines. They are not Blocks. They could be Blocks, but they typically wouldn't be. So that's where the analogy starts to break down a little bit. Now, the one thing that is similar typically is that a Family will be a discrete element. In other words, there is a Family for this wall and another Family for this door but you wouldn't typically have a Family for this entire Utility room.
If I zoom out a little bit, that is typically the domain of groups. So, I'm going to highlight one of these pieces of furniture, and what you'll notice is that the individual chair doesn't highlight, instead, there is a dashed box around all of the furniture in this floor plan, and when I click, you can see that all of the furniture in this Condominium unit is highlighted together. If you look at the tooltip that appears on the status bar, you see that that's all part of a Model Group. So, a group is actually a lot closer to being directly synonymous to a Block than a Family is because, with a group element, it's completely user-defined.
I can put any elements I like in a group, and then if I make a change to that group, it will change everywhere. So, for example, if I'd to select this Group and choose Edit Group and take this nightstand and delete it and perhaps take this chair over here and move it like so, and maybe rotate it, what we will see is that when I choose to Finish the group right here, not only did that change apply to this instance of the group, but it applied to this one as well. Notice the chair is moved.
Notice the nightstand is removed, this one as well, this one as well and the one over here. Because, all of those groups were instances of that same group definition. And so, the process I just went through would be very similar to editing a Block in AutoCAD. So, it really is like that old cliche of apples and oranges, in a lot of ways, Families, Groups, and Blocks are basically apples, oranges, and bananas. There are some similarities, but there're a lot of differences as well.
- Comparing AutoCAD and Revit
- Customizing Revit settings
- Exploring the Revit interface
- Organizing with categories versus layers
- Understanding families and groups versus blocks
- Using links instead of Xrefs
- Tracing, nesting, and exploding CAD files