Placing & Swapping Families — Load families and place instances; swap types

Historical Context & Motivation

Before parametric Building Information Modeling (BIM) tools arrived, architects and designers relied on drafted symbols—blocks in AutoCAD or hand-drawn legends—to represent real-world building components such as doors, windows, and furniture. Every unique object required its own drawing, and substituting one fixture for another meant erasing geometry and redrawing from scratch, a labor-intensive process that scaled poorly as projects grew in complexity. The concept of a reusable, data-rich family emerged from the recognition that most building elements share structural logic—a door is always a door, even when its width, material, or panel style varies—and that encoding that logic once should let designers produce infinite variations without redundant work.

Autodesk's development of Revit in the late 1990s crystallized this idea into a family-based parametric system in which every element placed in a model is an instance of a family type, governed by parameters that control its geometry, materiality, and metadata. This paradigm shift paralleled broader trends in object-oriented design thinking across software engineering and product design, where encapsulation and reusability became cardinal principles. For Visual Arts students accustomed to thinking about iterative form-making—swapping palettes, adjusting proportions, or testing alternative compositions—the family system offers an analogous digital toolkit: load once, place many, swap freely.

The central question this lesson addresses is deceptively practical: how do you bring external family files into a Revit project, place instances in your model, and then swap those instances to different types when your design direction shifts? Answering that question well means understanding the hierarchical relationship between families, types, and instances—a relationship that underpins nearly every operation you will perform in Revit.

Core Principles & Definitions

Every element you see in a Revit model—from structural columns to custom art installations—belongs to a family. A family is essentially a template that defines an element's geometry, behavior, and available parameters. Within each family live one or more types (sometimes called family types), which are specific size-and-property presets—think of them as stylistic variations on a theme. When you place an element in a view, you create an instance, a concrete occurrence of that type at a particular location, elevation, and host. This three-tier hierarchy—family → type → instance—governs how data flows through a Revit project and determines what you can change globally versus locally.

Visual Explanation — The Family Hierarchy

The diagram above visualizes the core data model you interact with every time you use Revit. Notice that the family occupies the top tier, acting as the structural container for all geometric and parametric logic. The types beneath it are essentially named configurations—each one locks a particular set of type parameters (dimensions, material assignments, visual overrides) while inheriting the shared logic of the parent family. At the lowest tier, instances are the tangible objects placed in your model views. They carry instance parameters—values unique to that specific placement, like orientation and elevation offset. The swap panel at the bottom demonstrates the key insight: reassigning an instance's type changes its inherited properties without disrupting its spatial position or host relationship, which makes type swapping an extraordinarily efficient design iteration tool.

How It Works — The Load, Place, and Swap Workflow

Step 1: Loading a Family into the Project

Loading a family begins with navigating to Insert → Load Family on the Ribbon, or by using the keyboard shortcut. A file browser opens, pointing by default to the Revit content library installed with your software. You can also browse to manufacturer libraries downloaded from sites like BIMobject, NBS Source, or Autodesk's own content delivery network. When you select a .rfa file and click Open, Revit reads the family definition—its parametric skeleton, embedded types, and metadata—and copies it into the current project's internal database. From this point forward, the loaded family and its types appear in the Project Browser under the corresponding category node (e.g., Doors, Furniture, Generic Models). Importantly, loading does not automatically place any instances; it simply makes the family available for future placement.

Step 2: Placing Instances

Once a family is loaded, you place instances through the Architecture (or Structure / Systems) tab, or more commonly by selecting Component → Place a Component for generic model families. The Type Selector dropdown in the Properties palette lets you choose which type within the loaded family you want to place. As you move your cursor into a plan, section, or 3-D view, Revit shows a preview of the element snapping to relevant hosts—walls for doors and windows, floors or ceilings for face-based families, and open space for freestanding components. A single click (or click-and-drag for hosted elements) creates the instance. Repeated clicks create additional instances, each independent in position but sharing the same type definition.

Step 3: Swapping Types

Swapping types is the operation that makes family-based modeling genuinely iterative. Select one or more instances in any view (use Ctrl+click for multi-selection, or filter selections by category). With the selection active, open the Type Selector dropdown in the Properties palette. It will display every type belonging to the same Revit category that is currently loaded in the project. Choose a different type, and Revit instantly reassigns the selected instances. Their positions, host associations, and instance-parameter values remain intact; only the type-level parameters—dimensions, materials, subcategory visibility—update to match the new type. This workflow is non-destructive and fully undoable, making it ideal for exploring design alternatives quickly during schematic and design development phases.

Detailed Breakdown — Family Categories & Swap Compatibility

Not all families can be swapped with one another freely. Revit enforces swap compatibility through its category system. Every family belongs to exactly one category—Doors, Windows, Furniture, Generic Models, Lighting Fixtures, and so on—and the Type Selector only presents types from families within the same category. A door instance can be swapped to any loaded door type (even from a completely different door family), but it cannot be swapped to a window type because Windows is a separate category. Understanding categories is therefore essential when you plan which families to load: if you want maximum swappability, ensure all related design options are authored under the same Revit category.

For Visual Arts students, the Generic Models category is particularly valuable. If you are modeling custom installation pieces, sculptural elements, or exhibition display systems, authoring all related components under Generic Models ensures you can swap freely between them. This is analogous to working within a single material family in sculpture: bronze castings can be swapped with other bronze castings of different form, but you cannot swap a bronze piece into a ceramic slot without fundamental process changes. In Revit, the category acts as that material-class constraint.

Worked Example — Gallery Lighting Redesign

Imagine you are designing a university gallery space and have initially placed pendant light fixtures throughout. The curator requests you explore track lighting as an alternative to better illuminate moveable exhibition walls. This worked example walks through the complete load → place → swap cycle.

Strengths, Limitations, and Common Pitfalls

Connection to Advanced Family Authoring & Dynamo Automation

The load-place-swap workflow you have learned represents the foundational interaction with Revit families, but advanced practice extends each stage significantly. Family authoring—the process of creating or modifying .rfa files in the Family Editor—lets you define entirely new parametric geometry, set up custom type catalogs with dozens of presets, and embed formulas that constrain proportions mathematically. This is where Visual Arts students with an interest in computational or parametric design will find the deepest creative leverage: rather than relying on manufacturer-provided families, you author bespoke components whose parameters map to your specific aesthetic and conceptual vocabulary.

As you move into advanced coursework or professional practice, the principle remains the same: the family system is designed so that intelligence lives in the definition, not in the instance. Every enhancement—whether it is a Dynamo-driven mass placement routine or a formula-driven type catalog with fifty glazing variations—simply extends the depth of that definition. The swap operation, in turn, becomes exponentially more powerful as the range of available types grows, enabling design exploration at a scale impossible with manual modeling.

Practice Problems

Lesson Summary