Building Information Modeling

Traditionally, the building industry delivered the building projects with manually created drawings on which the information was added by using notes and specifications. With the advance of CAD (Computer Aided Design and Drafting), this process was made more efficient. However, the methodology remained the same. Drawings became computer-based and the information was added on using paper-based pile of specifications and notes. These methods often resulted into uncoordinated, inaccurate and missing set of documentation.

Now, developments in Building Information Modeling (BIM) methods have brought a new perspective on how projects can be managed in the building industry. Here, the information plays a central role in developing 2D and 3D representations of the building model. Both information and the building model are interconnected. As the project progresses from concept towards execution and then operations, information keeps updating and so does the building model. This way, the BIM model becomes a repository of integrated and coordinated set of documentation for the project at the given stage of the project life cycle.


Image Courtesy: wikimedia commons

Thus, Building Information Modeling can be understood as a building design and documentation methodology that integrates coordinated, reliable information about a project from design through operations. The Autodesk® Revit® platform is purpose-built software for building information modeling.

Learn more about Building Information Modeling, HERE.



Create a project file

Project files in Revit have “.RVT” extensions. To create a RVT file, you may either choose to use an existing project template (RTE) file or start a project with no template file. Template files have pre-defined settings which assist the project to get started faster. For example, project units are predefined, basic families commonly used are pre loaded, materials are preset, etc. If you choose not to use any templates, you will have to start your project by defining all settings and load your required library elements. If you are a beginner, it is recommended that you choose a default template file that is provided along with your software library.

1. Create a new project file with a template

  • Open Revit software.
  • Click on New under the projects (OR go to File Tab -> New -> Projects) and choose an ‘Architectural Template’from the default list.

(Note: If you do not see a list of templates, click on Browse and go to the Program Data folder on the drive where Revit is installed. For example: C:\ProgramData\Autodesk\RVT 2019\Templates OR Alternatively, check the Autodesk folder under your User profile in the computer %ALLUSERSPROFILE%\Autodesk\RVT 2019\Templates)

M1 New project

2. Set up Project Units

Now, once your project file is open, next step would be to set up project units.

  • Go to Manage tab on the Ribbon -> Setting Panel -> Project Units M1 Project Units
  • In the Project Units dialog box, Under discipline -> select Common
  • Change the Length units to the unit of your choice(Ex: Meters)
  • Select required Rounding values (Ex: 1 decimal place) and Unit symbols to be displayed (Ex: m)M1 Units
  • Click OK for Format dialog box.
  • Click OK for the Project Units dialog box.
  • Units for the length has been successfully changed.

(For further practice: Change the Area, Volume and Angle units to Square Meters, Cubic Meters and Decimal Degrees respectively)

3. Update Project Information

After setting up project units, add some project information to your project.

  • Go to Manage tab on the Ribbon -> Setting Panel -> Project InformationM1 Project Info
  • Project Information dialog box will appear. Add the details about your project in this dialog box such as Project name, Client name, Project Address, etc.
  • Click OK when you are finished adding required information. If you do not know some of the information at this stage, it is okay. You can come back to this dialog box later and add information when you have it with you.

4. Specify Geographic Location for your project

To set your project to a real world site location,

  • Click Manage tab -> Project Location panel -> Location
  • On the Location Weather and Site dialog box, under Define location by -> choose default city list.
  • Under City, choose the city your project is located at.
    • If you do not find the city in the default list, you can also enter the Latitude and Longitude of the exact project site location.
  • Click OK to the location and weather site dialog box.

5. Save the project file

  • Go to File Tab -> Save
  • Give file name and Choose the file type as *.RVT (Ex: Learning Revit Online_Sample Project.rvt)
  • Click Options -> File Save Options dialog box will appear -> Choose the maximum number of backups you would like to have for this file.
    • Every time you will save, a previous version of the file would be saved as a backup till the maximum number of backups specified here is reached. After that, it will keep removing the oldest revisions and add a newer version of the backup file. Each backup file will get a suffix of “000n”(n=number of the backup version) with the project name.  (Ex: Learning Revit Online_Sample Project.0001.rvt)M1 save
  • Click Save. Now, you have successfully created a Revit project file.
  • To know more about File Save Options, click here.

Understanding Revit File Formats

Let’s understand different types of file formats in REVIT with following extensions:

M1 file formats

RVT – ReViT project file
The project file (RVT) contains your Revit model with its information. By using a single project file, Revit makes it easier to alter the design and have changes reflected in all associated views (plan views, elevation views, section views, schedules and so on). Having only one project file also makes it easier to manage the project (Although, typically increases the file size compared to CAD applications.)

RTE – Revit project TEmplate file
These are starting point for creating a new project. You may use one of the project templates (RTE) provided in your library as basis to create your project. Later, you may also customise these templates as per your office standards so that it saves you time and effort to make the settings from project to project. Learn more about project templates here.

RFT – Revit Family Template file
Revit family templates serve as starting point for creating a family (elements of Revit). It contains the information that you need for that particular type of family you would like to create. Learn more about family templates here.

RFA – Revit FAmily file
Revit family is the file that contains the model geometry and information of a revit element. You can learn more about Revit families by understanding REVIT elements.

Type and Instance Properties

In the previous chapter ‘Concept of Revit Elements‘, we discussed about how Revit elements are organized in a hierarchy:

Elements -> Categories -> Family -> Type -> Instance.

For many CAD users, families may sound similar to blocks or groups. However, the difference between CAD and BIM is the “information”. Thus, blocks and families are fundamentally different from each other because of the information they carry in their parameters and with which they can be controlled.

Each family is controlled by type and instance parameters within the project. Instance parameters affect individual instances only. Type parameters affect all instances of the same type in the entire project. To explain this, let’s go back to our example of chairs that we learnt in Concept of Revit Elements.

M2 Revit Elements

Now in this room, there are two types of desk chairs – blue and black. Let’s say that we want to change the color of all the blue chairs to red. If the color parameter is part of “type properties”of the family, then changing the value of the color in one chair would automatically affect all the 5 blue chairs present in the project. But, if the color parameter is part of the “Instance properties” then, changing the value of the color in one chair would affect only that particular chair. The remaining 4 chairs would remain blue.

In system families, type and instance parameters are pre-defined. For example, the thickness of the wall, by default, is a type property. Whereas, the height of the wall is an instance property.

For loadable families, you can decide which parameters to include as type and which as instance, depending on how you want to control the behavior of the family. This is typically done while you are creating a new family or editing an existing one.

Learn more about differences between type and instance parameters in a Video Tutorial by Autodesk.



What is Autodesk® REVIT®?

Autodesk® Revit® is a software product of Autodesk, Inc. It is built for “Building Information Modelling” which is one of the pioneering collaborative methods in building industry today.


  • Architects and engineers can now focus on DESIGNING, without spending much time over back office kitchen work of DRAFTING.
  • Contractors can use REVIT models to get faster quantity take-off, review interdisciplinary coordination, and efficiently manage documentation.
  • REVIT models serve as the base for many further BIM applications.
  • REVIT includes the functionality of all building disciplines – architecture, structure, mechanical, electrical and plumbing in one interface.

To know more about the software and to download the latest available version of ‘Autodesk® Revit®’ software, please use the official website of Autodesk.
If you are a student, you can download a free education version of the software from Autodesk Education Page.


Concept of Revit Elements

All elements in Revit are organized in a hierarchy of,

  • Elements
    • Categories
      • Families
        • Types
          • Instances.

Understanding Revit elements is very similar to understanding real world elements in a typical building project.

  • There are mainly three types of Elements in Revit:
    • Model Elements include categories that have 3D geometry such as Walls, Doors, Windows, etc.
    • Datum Elements include categories that are used as references for the project such as Levels, Grids, etc.
    • View-Specific Elements include categories that describe or document the project on a specific view such as Dimensions, Text, Annotations, etc.

Let’s take an example of Model Element category such as Door.

  • A specific design of a door is known as Family such as a Single Flush Door.
    • Each family of this element can have multiple types within it. For example, the Single Flush Door family with 0.8m, 0.9m and 1.0m width types.
      • Now, when you place a particular type of door at a particular location in your project, it is known as the Instance. So, if there are 4 Single Flush Doors with 0.8m type in the project, then we can count 4 instances of 0.8m Type of Single Flush Door family in the project.

To make it yet easier to understand, let’s take the following example of chairs in a room:

M2 Revit Elements

  • Element Type: Model Elements (because they contain 3D geometry)
  • Category: Furniture
  • Family: There are two different design of chairs in this example:
    1. Executive Chair
    2. Desk Chair
  • Type:
    • Executive Chair Types:
      1. Blue Chair
    • Desk Chair Types:
      1. Blue Chair
      2. Black Chair
  • Instances:
    • Executive Chair -> Blue Chair -> 6 Instances (around the table)
    • Desk Chair -> Blue Chair -> 5 Instances (in the left)
    • Desk Chair -> Black Chair -> 4 Instances (in right)

I hope these examples make it more clear for you to understand how elements are organized in Revit.  To further understand Revit elements, please review About Element Behavior in Revit

Starting a project in Revit

There are many ways to start an architectural project. The approach will depend on each designer’s preference and at which design stage you are beginning your project in Revit.

  • Approach 1: Starting with a layout

    • Most architectural projects begin by designing space layouts using lines or basic modeling tools such as walls, doors and windows. Once a layout is complete at one level, often the design develops vertically on different levels.
  • Approach 2: Starting with a reference

    • Some architects like to begin their conceptual work in CAD, SketchUp or other software tools. Once a concept is finalized, a REVIT model is then generated using the output drawings from CAD/other tools as references.
  • Approach 3: Using complex forms for conceptual design

    • Some architects like to begin their design by playing with space volumes and complex forms. Once the form is finalized, a building model is then generated based on that form. In REVIT, this is done through Massing tools. It is especially useful for complex form development during conceptual planning phase.

Please note that as this course ‘Basic 3D Modeling tools for an Architectural project‘ is focused on beginner level, the tutorials provided in this course are based on approach 1 and 2. If you are interested in learning more about approach 3, click on Massing Studies.