Revit is well known BIM Software. Revit uses .RVT files for compiling BIM Models. Several 3D Objects like walls, floors, ceiling, staircases, rooftops, windows, doors, and many more are crucial for construction of building. These objects are known as families and are saved in files with .RFA extension. These .RFA files are then imported to the .RVT ones. These families are the pre- built reusable elements integrated within a Revit model.
Revit Families or Components work in the same manner as blocks in AutoCAD. In AutoCAD only the distance between two entities is determined while in Revit if the dimensions are modified than the dimensions of the component linked to it are also altered.
Revit families are created externally, stored separately and then may be loaded into various projects as per the use. Majority of the families are built as 3D objects but there are several uses for 2D families also like tags and symbols.
Revit Families are of three types:
It is possible to create or delete system families. They are already defined in Revit. System families constitute views, dimensions, texts, etc and objects like ducts and pipes.
Component families such as devices, equipment, fixtures, etc can be created and stored in external library.
It is built within the project only. These cannot be re-used or shared between objects.
A Revit Model is considered best for Parametric Modeling. A Revit model consists of single database file containing plans, section, elevation and schedules. Thus, Revit model objects or component are coordinated. Revit Families are built in such a way that the dimensions are governed by parameters. Component Families enables this feature.
Component Families are controlled by various parameters which enables significant amount of flexibility. These are also known as Parametric Families. Parametric describes relationship between the components of model that allows fundamental coordination i.e. if anything in the project is changed than Revit architecture incorporates that change throughout the project.
Parametric Families provides an open graphical interface for design planning and forming and provides opportunity to design with minute details. Most importantly no coding or programming language is needed.
Examples to illustrate the functioning of Parametric Families:
- If the location of window is altered or it is removed or modified in Revit then with the help of Window family this modification is incorporated in complete project including plan, section, elevation, walkthrough etc.
- Edge of roof is connected to exterior wall in such a way that if the exterior wall is shifted then dimensions of roof are modified accordingly.
- If the partition between hinge and the door frame is altered, then using door family the partition is retained.
Parametric Families have become important tool in Revit Architecture as it is user friendly and provides significant customization and saves a lot of time. It provides flexibility while dimensioning thus minimizing manual work. Revit Families enables rapid work allowing Engineers to make changes quickly thus enabling them to upgrade model with minimal errors.