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Monday, 2 March 2015

Revit OmniClass: A Complete Bill of Quantities

Revit’s OmniClass Name and and -Numbering functionality is an extremely useful tool to create a bill of quantities which includes all relevant Revit categories in one schedule. This functionality is not used often enough, as it will take a bit of time to set up (It is however worth it in the end!)

The most important thing to remember, not only for this Bill of Quantities example, but for all of your Revit families, templates and projects, is to use Revit Best Practices. If you do things properly right from the start, you will reap the rewards not only for your current project, but also for all existing and future projects.

To use the OmniClass functionality, take the following points into consideration:

  • Proper Revit family and type naming conventions
  • Company specific, or custom, OmniClass Taxonomy file
  • Correct OmniClass Name and –Number assigned to families
  • Properly set up Bill of Quantities schedule
An OOTB mechanical Variable Air Volume unit was placed in a project. The type properties of this unit contains the OmniClass Number, and respective OmniClass Title that has been assigned to the unit. These properties are greyed out, and thus not editable.

To access and modify the above mentioned properties, one has to enter the VAV unit family environment. The OmniClass Number can be created or modified from the instance properties. A list of OmniClass Numbers and Titles will show (Extracted from an external OmniClass Table 23 Product Classification text file)

The OmniClass Taxonomy text file can be found in the following location:
C:\Users\<USER NAME>\AppData\Roaming\Autodesk\Revit\Autodesk Revit 2015

The text file will contain the OmniClass Number in the first column and the OmniClass Title in the second column. Should you require to edit the Omniclass Titles and Numbers, remember to create a backup file, to ensure that you will be able to restore the file should something go wrong.

We can now create a Multi-Category schedule, where we can extract various common parameters from, such as the Count, Omniclass Number, Omniclass Title, Family and Type, and Cost. This is where the family naming conventions come in handy to ensure that you have consistency in your schedule, and that the schedule looks like a MEP Bill of Quantities should look like.

With some minimal editing being made to the schedule, such as changing the Sorting and Grouping options, as well as the Formatting, you should be able to extract a graphical representation as per the image below.

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