BIM and Revit: an introduction

This content is adapted from BIMuzer.

If you’re in the construction or building industry, you may occasionally be required to talk about building information modeling (BIM) and Revit®, a software package used to create BIM models. This guide will help you confidently dive in regardless of your experience.

What are the differences between BIM and Revit?

BIM is the overall process of creating a three-dimensional database in the form of a model of information that pertains to the design of a building. Revit is just one of many software applications under the BIM umbrella that lead to an efficient design of space. Revit is the main application that falls under BIM, but there are other applications designed to perform certain functions that Revit cannot achieve or is ineffective at tackling. The following are just a few examples of other BIM applications:

• Ecotect™ and Green Building Studio, both of which are designed to test the efficiency of a design with regards to its impact on the environment and how the environment impacts it
• Navisworks®, which merges building information models from various disciplines in a single environment to see how they physically interact, allowing designers to make necessary adjustments before construction begins

Is there more than one version of Revit?

There are three different discipline versions of Revit. Each one has tools geared to that particular discipline. Fortunately, all three are designed to speak the same language. Therefore, a model created in one version of Revit can be inserted into the modeling space of another. The following is how multiple disciplines typically work together in Revit:

• An architect will begin building the design model in Revit Architecture.
• At an agreed upon point, the architect will send the model to the structural and MEP engineers.
• Each discipline will link the architecture into their workspaces within their chosen version of Revit, e.g. Revit MEP or Revit Structure. In other words, they will instruct their own discipline versions of Revit to connect to the model provided by the architect and show it graphically within the same space.
• Once linked, experts from each discipline will begin inserting their own work including beams, trusses and columns for the structural engineers, and ducts, pipes and electrical connections for the MEP engineers.
• Next, the engineers will send their individual models back to the architect, minus the original model provided by the architect.
• The architect will link each model into his or her architectural model, and the individual models will appear in their correct locations. Additionally, all objects created by the engineers will contain all of the original information inserted within them.

How often are the various versions of Revit updated?

You’ll see multiple versions of Revit as Autodesk, the makers of Revit, releases updates. Each time an update is released, a build number is added to the end of the version name. If you’re collaborating with someone, you’ll need to use the same year and build version of Revit. These numbers are consistent from Revit Architecture to Structure and MEP. This is also important because once a model is saved in the current version, it cannot be saved in an earlier version.

Can I use Revit to create drawings?

There is no such thing as a Revit drawing. When a project is AutoCAD-based, each individual file is a drawing file. You can ask someone to provide drawings in AutoCAD format. When using Revit, you should ask for the Revit model if you require comprehensive project information. If you need individual drawing sheets, you can still ask for AutoCAD drawings. You can also ask for PDFs of the drawing sheets. If you’re working in Revit and are asked for drawing files, you can extract them from the model individually or as a complete set of drawing sheets in AutoCAD or PDF format.

Does Revit use multiple files?

While AutoCAD-based projects typically use many files, a Revit-based project relies on, in most cases, a single file. AutoCAD-based projects have individual files that represent individual drawing types (e.g. plans, sections and elevations) inserted into single files, representing individual drawing sheets. If you extrapolate that information for a large project, you will have many files.

In contrast, Revit-based projects tend to be a single-model file within which specific drawing types are set up as views of that model. Additionally, that same file includes sheets with those views. Since all of these sheets and views come from the single model, you can make changes to the model in a view (or sheet), and the change will be applied universally. With all information in a single Revit model, Revit project files tend to be large. Thus, more powerful computers are typically needed to use Revit efficiently.

Does Revit provide 2-D or 3-D views of a project?

When working in Revit, you’re working in two dimensions and three dimensions simultaneously. Even if you’ve created the wall in a plan view, if you switch to a three-dimensional, section or elevation view, you will see that the height is also represented. This is the case for all objects in Revit. Remember that “working in 3-D” isn’t limited to creating renderings or animations; if you’re creating plans, sections and elevations, you’re working in 3-D.

What are BIM standards, and what do they have to do with Revit?

When an office selects Revit as its standard platform, they also choose various graphical settings, known as standards. These dictate how drawings will look. Examples of settings include:

• Line thicknesses (or line weights).
• Text fonts and font sizes.
• Title blocks and scales (e.g. 1/8”=1’0” for plans, and 3”=1’0” for details). When a new project is kicked off in Revit, the person responsible for BIM efforts will use a file that contains all of these settings; this file is known as a template file. You might be asked for your office’s BIM standards. If you do not have these documented, you can instead provide your template file, as it contains 99 percent of your BIM standards.

What are questions I should ask prior to the start of a Revit-based project?

Whether you’re an architect, consultant, contractor or subcontractor, asking these questions will be helpful when a Revit-based project is proposed or about to begin.

• What year and build version of Revit will be used for this project?
  • Remember, all parties must use the same year and build version so that data can be easily exchanged.
• Should everyone conform to a specific template file and BIM standards?
  • If you are not coordinating all efforts and/or don’t have a template file containing BIM standards, it is likely that the coordinator has a template file. Make sure to obtain and use this template as a starting point for your Revit model.
• Has a Revit model been started? If so, can we use it as a basis for our work?
  • An existing model will give you a head start, because you can bring it into Revit and use it as a host for your task, from additional design work (e.g. a curtain wall) to an HVAC system or structural system.
• If a Revit model has not been built, can I send AutoCAD drawings?
  • AutoCAD drawings can be inserted into your Revit model and used as a basis for your work.
• What is the schedule for uploading and downloading BIM data?
  • Establishing a schedule for the exchange of data will allow you to establish more realistic deadlines.
• How often will BIM coordination meetings be scheduled?
  • Regularly scheduled meetings will allow all interested parties to continually ensure that their portion of the design physically complements the rest of the design.
• Will Navisworks be used for 3-D coordination?
  • Navisworks is a software application that can bring together 3-D models from multiple applications; it will analyze how the models physically interact and specifically look for unintended conflicts.

These tips should give you a basic understanding of BIM and Revit, and the questions you should ask as you begin your work. Revit Essentials and Project Manager training will only improve your knowledge and ability to make decisions regarding staffing, budgeting and scheduling of a Revit-based project.