All In the (Revit) Family

The elements in Revit that you will interact with are organized in a hierarchy that is pretty straightforward:

• Category - the highest level of grouping and are usually easily identified logical ways so you know what is what. Categories are things like Walls, Door Tags, Pipes, etc.
  • Family - this a the next level (and the one we will focus on in this blog post). It groups objects by the similar geometry and parameters. Often the rule for what is one family vs another depends on the category and the use.
    • Type - further drilling down, types are a specific geometry and parameters. For example, Inset Door might be a family, but 36" x 48" will be a type.
      • Instance - the last stop on our element structure, this is a single element you have placed in a view.

As you work your way down, different parameters get associated to the elements and can be controlled at different levels impacting all the associated elements down the hierarchy. Most items in your model let you see the entire hierarchy. Some, like Rooms and Spaces, will hide steps from the UI because there is nothing for users to manipulate.

Let's Talk About Families

Beyond simply having different families (Inset Door vs Wrapped Door) there are also different kinds of families to understand. Some are controlled by Revit when you use them and some you get to choose. Each has very specific uses so understanding what they are and when they show up can really help keep your model in good shape.

System Families

When talking about building components, meaning stuff you can "kick," System Families are usually things that are built or assembled. Things like walls, roofs, piping systems are all System Families.

There are also some System Families that are not "kickable" but are significant to the design and documentation of a project: grids, levels, and sheets (not a sheet border) among others.

An important thing to know about these is that they must live in a Revit project file or project template. You cannot have a "wall file" that you load into a project from a library. Now, you can certainly have a project file with a bunch of walls in it that you can copy into another project, but that is through the Transfer Project Standards tool.

Sometimes, System Families are referred to as Host Families, especially the physical building-related ones, because you often host other elements to them.

Loadable Families

For building-related items, these are things that generally are bought and installed in a project: doors, windows, furniture, joists, pumps, etc.

For documentation, these are things like tags and the afore mentioned sheet border.

Unlike System Families, Loadable Families are created in a file outside the project file and then loaded in (hence the very clever name). If you are told to "load in a component" you are most likely pulling in a Loadable Family. Your company's family library is going to be filled with a bunch of these RFA files. Some already live in your Revit project file, but you can actually save them out to their own file if you need to.

The majority of content that you will be dealing with will be Loadable Families. Revit has specific geometry modeling tools and a specific UI to facilitate making these.

In-Place Families

In-Place Families are the wildcard of the family bunch. These are modeled like Loadable Families, but they live in a Revit project like System Families. The idea is if you have a unique one-off element that you either:

• Cannot be made with the default System Family tools
• Has to rely on complicated building elements and geometry

Then you want to consider an In-Place Family. The key to remember is that it should be unique - there should be only one of them in your project. The reason for this comes down to model file size.

Let's say I use a door that is a Loadable Family and it's 2MB (probably too big, but it's easy for the math). When I load it into my model I have added 2MB to the overall size. Then when I place instances of that door, the extra size that is added is negligible, because each instance is looking at that loaded family for its geometry and a lot of its rules. So even if I place 100 of them, it's only going to make my Revit project file a tiny bit bigger.

Now, if I create an In-Place door and it's 2MB, the first one I make will add 2MB to my project file. Unlike the loadable component, every time I make a copy of it I am not pointing back to the original. So if I add 100 of them I have now added 200MB to my Revit project file.

So while they are useful, In-Place Families should be considered a last resort.