Before we get into this, I want to make sure I give credit to Daniel Hurtubise of Revit It! and Katherine Meeder, BIM Specialist at HNTB Architecture for all their work in putting together this document.
What is a Family?
A Revit Family is the most basic building block or component in a Revit Architecture model. Families are reusable and can be transferred from project to project. You can use System Families from existing Revit projects or templates by using the File > Transfer Project Standards. Component Families can be loaded from family libraries using the File > Load from Library > Load Family.
Families can be either 2D or 3D. Families are easily swappable as the project progresses from schematic design quality into the construction document phase. Properly created Revit families can minimize the size of the BIM model file while providing a high level of detail that can be viewed in the schedules, tags and labels.
Revit uses 4 types of families:
Systems Families (walls, text, ceilings, etc.)
Component Families (doors, windows, plumbing fixture, equipment, furniture, etc.)
Mixed-Use Families (grids, levels and stairs)
In-Place Families (Families that are created within the context of the project. The family exists only in the project and cannot be loaded into other projects easily) They have limited categories. They add a lot of geometry.
Where to Start?
Before creating a family in Revit, users should consider the following questions regarding their intended use of a family. A properly created family can provide a wealth of data and graphical benefits with minimal impact on performance, but it all starts with planning.
1. Sketch the Family’s end result.
This helps you gather your thoughts and every view and level of detail that you will require.
2. Does this family require a host (or does it attach to another object)?
Is this family typically attached to another design element - a wall, or maybe a ceiling? Possibly it is a roof mounted mechanical unit or skylight. How this family is hosted (or what it does or does not attach to) will determine which template file should be used to start the family. If it is hosted, is it face based?