What are Revit Families? ( Downloads at the bottom )
In Revit, Families are a fundamental part of the Building Information Modelling (BIM) process. A Family in Revit refers to a group of elements that share common characteristics, such as geometry, parameters, and behaviour. These elements can represent a wide variety of building components, such as doors, windows, furniture, structural elements, and mechanical components. Each Family is created to fit a specific role within a building model, allowing users to represent a vast array of real-world objects within their designs.
Revit Families are broadly classified into three categories:
System Families: These are families that are part of Revit by default, such as walls, floors, ceilings, roofs, and foundations. System Families are integral to the structure of the software and cannot be modified at their core level, though their instances and types can be adjusted.
Loadable Families: These families are external to the Revit project and can be created or modified by users. Examples include doors, windows, furniture, lighting fixtures, and equipment. These families are typically stored in external files (Revit Family files) and loaded into a Revit project as needed. They can be customised to meet specific design requirements and project needs.
In-Place Families: These are families that are created directly within the project, typically for custom or one-off elements that do not need to be reused. They are often used for bespoke components that do not conform to a standard family or when an element's geometry is highly unique.
REVIT Family Types and Parameters
Each Revit Family has types, which define the variations of the family element. For instance, a Family for doors could have multiple types, such as a single door, double door, or sliding door. Families also contain parameters that control various properties of the elements, such as dimensions, material properties, and performance characteristics. There are instance parameters that are specific to individual instances of the element (e.g., the height or width of a particular door), and there are type parameters that define the properties for all instances of a specific type (e.g., the material of all doors of that type).
Families help ensure that the BIM model is flexible, allowing for easy modifications, adaptations, and consistent updates across the project.
Why CADMAP Needs to Use Revit Families for Different Types of LOD Revit Models
CADMAP, likely a company or team involved in producing BIM models, must use Revit Families for their different types of Level of Development (LOD) Revit models for several important reasons. These reasons relate to the need for consistent model management, accuracy, efficiency, and collaboration across the lifecycle of a building project.
1. Standardisation and Consistency
Revit Families ensure standardisation across the entire model, particularly when creating LOD models at different stages of development. Using Families allows CADMAP to maintain consistent and predictable representations of elements at each LOD. This is crucial for ensuring that every part of the project conforms to the required design specifications, ensuring uniformity in all project deliverables.
- For example, a door Family might represent a generic door at LOD 100 (conceptual stage), but as the project progresses to LOD 300 (detailed design), the Family will evolve to include precise dimensions, materials, and performance data that define the door more specifically for construction and fabrication.
2. LOD (Level of Development) Requirements
Level of Development (LOD) describes the amount of detail and accuracy of a model element at various stages in the project lifecycle. Different LODs are defined as follows:
- LOD 100: Conceptual or massing stage. Elements are represented as simple, generic volumes or placeholders.
- LOD 200: Approximate geometry. Elements are represented with approximate sizes and locations.
- LOD 300: Detailed geometry. The elements are represented with precise geometry, dimensions, and relationships, suitable for construction documentation.
- LOD 400: Fabrication stage. Elements are fully detailed, showing how they will be fabricated and installed.
- LOD 500: As-built. Elements reflect the actual conditions after construction.
Using Revit Families allows CADMAP to manage the evolution of these elements through the different LODs. As the project progresses, the Families can be updated with more detailed and accurate information to meet the necessary LOD standards. This ensures that the model provides the right level of detail at the right stage of the project, avoiding the risk of over- or under-representing elements.
3. Efficiency in Data Management
Revit Families allow data management at the object level, making it easier to control the parameters, geometry, and properties of components as the model evolves. This efficiency is particularly important when CADMAP is tasked with creating models at multiple LODs.
- For instance, at LOD 100, a Family might contain only basic parameters such as size and location. As the project moves to LOD 300, the Family will contain detailed parameters such as material types, structural properties, and specific installation requirements. This allows CADMAP to efficiently modify and update these elements without reworking the entire model.
4. Flexibility and Parametric Design
Revit’s parametric design functionality means that once a Family is created or loaded into the project, it can be easily modified, and these changes will propagate across all instances of the Family. This is particularly useful for projects that require frequent updates and modifications as they progress through different LOD stages.
For example, if the size of a window changes at the LOD 200 stage, CADMAP can modify the window Family, and all instances of that window across the project will automatically update. This parametric flexibility ensures that any design changes are easily managed and maintain the accuracy of the model.
5. Collaboration and Interoperability
BIM models are used by a variety of teams, including architects, engineers, contractors, and fabricators. The use of Revit Families ensures that the model remains interoperable between different disciplines and software tools. CADMAP can load standard Families into the project, ensuring that each discipline works with the same component representations, reducing errors and improving coordination.
- For example, a door Family might be used by the architect to create the basic layout, by the structural engineer to check for load-bearing requirements, and by the contractor to verify that the door fits into the space. Having a common Family across all stages of development ensures that all teams are working with the same data.
6. Reusability and Consistency Across Projects
Revit Families can be reused across different projects, which helps CADMAP maintain consistency. For example, if CADMAP has created a standard door Family for one project, they can reuse the same Family in another project, ensuring the same geometry, properties, and parameters are applied across multiple models. This also saves time and reduces the risk of errors when starting new projects.
7. Accuracy in Construction and Fabrication
At higher LODs (e.g., LOD 400 or LOD 500), Revit Families become critical for the construction and fabrication process. For instance, when a Family reaches LOD 400, it may contain detailed information about how an element is to be fabricated, installed, and assembled. CADMAP’s use of Families ensures that each component has the precise information needed to be correctly fabricated or installed in the real world, helping to reduce the risk of mistakes and ensuring accurate construction outcomes.
