Creating Revit Families for Architectural Projects

by Kuldeep Bwail Director, XS CAD Limited

Architectural projects embody the marriage of design and functionality. Fundamental to architectural integrity is a structure’s design. An effective and aesthetically appealing design requires extensive planning, and part of this planning can be done in 2D or 3D. Increasingly, architectural design is executed in 3D for improved accuracy and ease of communication for industry outsiders. Just as every great building begins with a single brick or plank, architectural design in software such as Revit begins with a Revit family. Revit family creation is a specialised field of expertise that is used for Revit family modelling in architectural design drafting.

So, what are Revit families?

A family is a group unit, much like real families, but a Revit family is a group of elements. These elements have a common set of properties, or parameters, and they are represented graphically. Again, similar to a real family, elements in a family may have different values for a few, or all, of their parameters. These elements with different parameters are known as family types or types. The Family Editor tool is used to change elements or create new elements to suit project requirements. The Family Editor helps in creating Revit families with parameters.

Every element added to a project developed using Revit uses families. Examples include structural elements, such as walls, roofs, doors and windows and callouts, fixtures, tags and other components that are used for documentation. Preinstalled and created families allow the placement of standard and customised elements in a model, respectively. Design changes become easier using families, because they allow control over similar elements.

Besides doors, windows, walls, roofs, slabs, stairs, curtain walls and ceilings, other categories of elements can be created using Revit families. The Furniture Category has families and family types that help create different kinds of furniture, such as desks, chairs and cabinets. The Structural Column category has families and types that create columns that are wide-flanged, precast, angle and others. Similarly, the Sprinkler Category helps create different kinds of sprinklers. These families within a category may have different functions and may ultimately use different materials, but they are related. Each type of a family has a graphical representation. An element that has been created using a particular family and a specific family type is known as an instance of the element. Every instance has properties. Element parameters can be modified without changing family type parameters. The change only affects the instance, the single element. Modifications made to the family type parameters, however, result in alterations to all element instances within the family type.

Customising Families

Revit has different kinds of families, such as system, loadable and in-place families. System families are preinstalled families and create basic elements, such as walls, roofs, ducts and pipes. System families are neither loaded into projects from external files nor can they be saved in external files. The settings on system families include types for levels, grids and drawing sheets.

Loadable families are created and then uploaded into the project. They are used to create doors, windows, fixtures, furniture, plants and any other elements that be bought, transported or fixed in and around a building. Loadable families are commonly created and altered in Revit, as they are customisable. They are created in external RFA files and loaded into the project. When a loadable family contains many types, type catalogs can be used so that only the selected type of family can be differentiated and can be loaded into the project without loading all the types. Loadable families can create specific kinds of families known as nested and shared families.

In-place families can create customised elements. When a project requires a unique element, in-place families are developed with a specific geometry. In-place geometry will then reference other project geometry and will modify itself according to the changes in the referenced geometry. To create an in-place element, Revit creates a family with a single-family type.

In the area of Revit MEP family creation, Revit family modelling is useful to help analyse lighting in a space, room or larger project. Light sources have their own properties when they are used in a modelling environment. Families can be created with multiple light sources using nested families, which are families within other families. The host geometry of the principal family is used and various lighting fixtures can be embedded.

Using the modelling capabilities in Revit’s stable, light can be analysed in multiple ways.

Revit family creation is required to complete BIM models and to operate them. A parametric 3D model has family objects added to it. The model then has all the data within the inserted object and this data can be modified. Interior design objects, such as tables, chairs, armchairs and sofas, are also part of the architectural design gamut. Besides graphically representing furniture, the Revit family has data and functions, which are defined parameters, that enable interaction with the model that hosts it, because each Revit family has parameters specific to it.

Space management is another area where Revit family creation is useful. Space management or room management can be managed well with Revit family modelling. The function and form of a building is primarily dependent on the size, shape, function and closeness between rooms or spaces. These spaces can be organised, positioned and assigned data using the Revit BIM platform. Room shapes can be set up with customised Revit family creation. For example, Space Planning families help create coloured bubble diagrams, where 2D and 3D families can be converted to wall objects.

The application known as Dynamo is a useful plug-in for Revit, which enables users to connect elements to use room and area data to automatically create Space Planning Revit families. Details of an individual room or space are fed into an Excel sheet. Name, quantity and dimensions can be set as parameters in Revit. Dynamo can mass families in Revit from the Excel sheet, making it possible for users to work on, modify and develop objects. Layouts can be documented for planning, as elevations or for rendering purposes. Changes in objects can be documented by using Dynamo to export to Excel.

Both exterior and interior walls can be created by using Wall by Face, picking any side of the Space Planning families. Perimeter boundary lines can be drawn around families to add floors. Similarly, rooms, doors, windows and other elements can be added.

Heights of rooms or spaces in the model are important to know while planning. Room or space heights must be tall enough to accommodate light fixtures or sensors on the ceiling. When a model has a space element, a ceiling and a single light fixture, the Layout Assistant can add other light fixtures depending on how much illuminance is wanted.

Lighting analysis, furniture and space analysis are just a few of the many functions that can be performed with Revit family creation. Creating Revit families with parameters in a Revit BIM environment has innumerable applications. Experienced professionals who are proficient in Revit family modelling and related services can help increase the scope and accuracy of architectural design drafting, at home or overseas.