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Revit for structural engineering & design
10 December 2018
Kuldeep Bwail

Widening Opportunities with Revit Family Models

Construction design practices have come a long way. Tasks enabled by updated software have contributed significantly to the progress of design practices. Increasingly seen as best suited for construction design, Revit presents several useful features, such as the use of Revit family models.

Though the models are not detailed enough to use for manufacture, its usefulness lies in its ability to create uniformity, accurate sizing and depict aesthetics that are precise, all while using small models to create larger, more complex ones.

Firstly, what are Revit family models?

Revit enables the creation of object-based models. In Revit, everything is part of a family, all elements. This family, similar to biological families, have an established hierarchy. Right on top are categories, which are pre-defined in the software and cannot be changed, removed or created. Many categories exist in Revit, including model and annotation categories. Model categories consist of elements in the building model, such as walls, doors, floors, stairs or beams. Annotation categories consist of text, dimensions and tags.

Categories, such as walls or doors, come in a variety of shapes, sizes and other features. To organize elements of a category, the next level is the family. So, Revit families are groups of like items with the same look and behavior. For example, the ‘wall’ category may have a ‘basic wall’ family and the ‘door’ category may have a ‘single-flush door’ family. Revit families include views of floor plans and sections.

The two main kinds of families are the system family and the loadable family. System families are built into the software and cannot be changed in the interface. They cannot be created or deleted, and their properties are pre-defined. A family may have several ‘types’. A ‘type’ is a group of variables, such as sizes, materials, etc. A family can have many types, each with editable settings. System families that have model elements are known as ‘host’ families, which are families that can provide support for other model elements. Component families need hosts, such as doors that need wall hosts and light fixtures that need ceiling hosts.

Loadable families are developed as external RFA files and imported, or loaded, in projects.

They are typically used to create:

  • Components usually bought, transported and installed, such as windows, doors, casework, fixtures, furniture
  • System components, such as boilers, water heaters, air handlers and plumbing fixtures in Revit MEP family creation
  • Customised annotation elements, such as symbols and title blocks

Due to its ability to be customised, loadable families are more commonly created and modified. When many types exist in a Revit family, type catalogs can be created, which enables the user to load only those types required.

A third type of family is called the ‘in-place’ family, which is similar to a loadable family, but is created in a project, for that project alone, and cannot be used in other projects. In-place families of walls, roofs and floors facilitate customisation for unique elements in a project. In-place families can depict special conditions or special design scenes.

Key Revit Family Terms

Model Element- An element that represents actual building geometry

Host Element- An element that provides structure for other model elements

Host-based Loadable Element- An element inserted into a host

Freestanding Loadable Element- An element that can be added without a host

Annotation Element- An element with text, dimension tags and symbols

It may not be feasible for everyone to start project design on Revit models. For those who have an abundance of CAD drawings that need to be converted to Revit models, a few options exist.

CAD Conversion

At times, a project’s initial phase has been designed with 2D CAD. Project managers may want to bring Revit models into the next phase. With similar details, drawings can be converted to 2D Revit families, making it possible to add further details to the project. When properly developed, BIM and CAD can be combined, since details are already drawn in 2D, making them efficient. They can be reused in Revit.

With the flexibility of creating Revit models, it’s worth looking at some of the features of Revit modelling.

Object-based modelling involves the development of objects using a variety of objects with stored values of the instance variables in an object. These values are other objects. Modelling methods support object-based model with analysis, design and execution during the design stage. The initial model is abstract, since external details are focused on. During further evolution, the model develops a greater amount of details. This results in understanding the system’s construction and its function.

The small individual models available as Revit families placed in the larger project model are important for several reasons. If the building’s side needs to be stretched, the walls, floors, roof and ceilings are adjusted accordingly. If a window is removed from a single view, it is removed from every view. Models of pipes can be checked for clashes and easily rectified. There is less rework due to errors. Overall costs are reduced in construction. Projects created in BIM are increasingly popular and more professionals will be using BIM technology down the line.

As many firms struggle with making the move to Revit modelling, outsourcing is emerging as a viable alternative.

Why Outsource Revit Modelling

Revit 3D modelling developed from 2D CAD drafting. The new ideas and benefits that 3D modelling brought with it are the 3D depiction of engineering drawings, floor plan designs, 2D CAD drawing services, architectural plans, Revit conversions, etc. Simple 2D drawings may not accurately convey the details of a structure, whereas 3D modelling is easy to comprehend, clear and help further develop design concepts.

Overseas CAD services offer a host of solutions to firms struggling with catching up to the Revit BIM revolution, such as converting 2D to 3D modelling with Revit, Solidworks and Inventor software. Models can be prepared from sketches and software migration from 2D to 3D modelling using Revit.

Offshore Revit modelling helps provide customised services at affordable rates, with the expertise of experienced Revit professionals. Some of the services delivered include:

  • Architectural 3D modelling
  • 3D architectural rendering
  • Structural 3D modelling
  • 3D mechanical modelling
  • Building 3D modelling
  • Prototype modelling
  • 3D product modelling
  • BIM modelling
  • AutoCAD MEP models
2D to 3D conversion

From hand-drawn sketches, pictures or scans to 3D models, the CAD services journey reaches a pivotal point. At this point, Revit outsourcing companies are poised for effective contributions. They are proficient in the required software application, use Revit architecture and MEP, Solidworks, Inventor and 3D Max software to deliver 3D models and realise concepts. Realistic views are provided quickly and efficiently. With the versatility offered by Revit family models and the vast availability of experienced and expert technical support, many firms can concentrate on a wider array of potential projects to be involved with.