Properties Generator v1.1

Object modelling guidelines

To assist with the creation of the geometric/graphical object using a BIM authoring application, such as Revit or ArchiCAD. NATSPEC recommends following the requirements of the Open BIM object standard (OBOS). 

The OBOS is available for free download from the NATSPEC BIM website, or by clicking on the following link: 


The NATSPEC BIM Properties Generator and the OBOS are mutually supportive tools for the creation of standardised BIM objects, with the content of the NATSPEC BIM Properties Generator being fully aligned with the information requirements of the OBOS.

The OBOS  therefore also includes requirements to assist object creators in regards to file naming, IFC designation and property sets for object types that are not currently included within the NATSPEC BIM Properties Generator.  

The aim of the OBOS is to standardise and rationalise an objects graphical and non-graphical content, to improve its functionality and interoperability between BIM applications, so as not to compromise the performance of the project model into which it may be placed. 


The content of the OBOS is listed below:

1.0 BIM Objects

- 1.1 BIM components and assemblies

- 1.2 Proprietary and generic BIM objects

2.0 Naming Conventions

- 2.1 General naming requirements

- 2.2 Object file naming requirements

- 2.3 Property naming requirements

- 2.4 Property set naming requirements

- 2.5 Material naming requirements

- 2.6 View control naming requirements

- 2.7 Material image file naming requirements

3.0 Object Classification

- 3.1 Object IFC designation

- 3.2 Object classification

4.0 Object Properties & Property Grouping

- 4.1 General object property requirements

- 4.2 Object type or instance properties

- 4.3 IFC properties

- 4.4 Administration properties

- 4.5 Proprietary object properties

- 4.6 Classification properties

- 4.7 Construction specification properties

- 4.8 Asset/Facilities management properties

- 4.9 Product performance properties

- 4.10 Property grouping (Property sets)

5.0 Graphical/Geometric Object Modelling

- 5.1 Object graphical detail

- 5.2 Geometric modelling requirements

- 5.3 What to model

6.0 Object Functionality

- 6.1 Object performance

- 6.2 Object relationships

- 6.3 Visibility/Views

- 6.4 Parametric behaviour

7.0 Import, Export and Linking

- 7.1 Importing information

- 7.2 Exporting BIM objects

8.0 Definitions & Glossary