Revit categories and classification systems

Standards for classifying building elements have been around for some times, but building information modeling gives us new perspectives for using them.

There is a handful of these classifications currently in use. The Construction Specifications Institute produce the MasterFormat and UniFormat, used in United States and Canada. The Construction Project Information Committee in the United Kingdom provides Uniclass and Uniclass 2. And the “Catalogue des articles normalisés” was used in Switzerland even before computers were able to manage it.

Revit provides two built-in type parameters to manage such classification systems, the Assembly Code and the Assembly Description. These parameters allow us to link any Revit type to an existing classification system.

This classification system can be loaded in Revit through the Assembly Code interface.

Autodesk provides us with the Uniformat classification, through the UniformatClassifications.txt. This tab-separated values text file define the classification structure with four columns:

• The Classification Code is the number associated with each item in a given classification. It is linked to the Assembly Code in Revit.
• The Description is the text associated with each item of the classification. Once we add an Assembly Code to a Revit type, this description appears in the Assembly Desciption.
• The Rank define the hierarchy of the item in the classification. This allows Revit to display any linked classification in a tree view.
• Finally, the Revit category Id allows us to create a first mapping between classification items and Revit categories. This allow us to filter by Revit category while assigning Assembly Code.

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