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Starting with a CAD File in SketchUp

Like many SketchUp users, you may want to use your CAD files to create excellent, useful, and lightweight SketchUp models. Importing and exporting common CAD file formats has always been part of SketchUp's DNA, but CAD files imported into SketchUp do have a few known quirks that you can sidestep if you know the tips explained in this article.

Here are the known issues that you may find after you import a CAD file into SketchUp:

  • The size or scale may not import correctly. This is especially true if you weren’t sure what unit of measurement was used to create the CAD file. (See Importing and Exporting CAD Files for details about matching the units.)
  • The lines in an imported CAD file often don’t connect to form SketchUp faces. Hunting down all these little gaps can be tedious — unless you know a few tricks explained in this article.

Whether you’ve never worked with a CAD file imported into SketchUp before or have lots of experience importing CAD files, the tips and examples in the following sections can help you start modeling with your file in SketchUp lickety-split.

Tip: To import CAD files into SketchUp, you need a SketchUp Pro license.
Table of Contents
  1. Preparing an imported CAD file for modeling in SketchUp
  2. Building a model from a CAD floor plan
  3. Adding doors and windows to the model

Preparing an imported CAD file for modeling in SketchUp

After you import a CAD file, following these steps can help you make sure the CAD file is ready for modeling. These steps assume that you don’t create a 3D model directly from the CAD geometry, but instead, use the CAD geometry as a reference for creating a SketchUp model.

Tip: Why use the CAD file as a reference? The main reason is because CAD geometry is often way too complicated to create a useful SketchUp model. When in doubt, re-creating the model with SketchUp's native drawing tools typically produces better and more consistent results than trying to manipulate the imported CAD geometry. Also, imported CAD geometry is likely full of gaps that need to be closed to create faces. If you’ve imported a floor plan, for example, drawing over a floor plan to create a new model is easier than hunting and pecking to find and fix all those gaps. If you need to use your CAD geometry, however, check out the Edge Tools 2 extension by user ThomThom. This extension can clean up terrain and CAD files for you by simplifying curves and closing gaps. To install the extension, select Window > Extensions Warehouse, search for the extension by name, click the Download button (if needed), and click the Install button.

Here’s a recommended workflow for getting an imported CAD file ready for modeling in SketchUp:

  1. Check the size of the imported CAD geometry. Choose an entity with a measurement you know and check its size with the Tape Measure tool (). If the size is incorrect, the Tape Measure tool also enables you to scale the entire model so that the dimensions are correct.
  2. Make sure the CAD geometry is a single group. If your SketchUp model contained any geometry before the import, the imported CAD geometry is grouped automatically. If not, you need to select all the CAD geometry and turn it into a group. Selecting Geometry offers tips on making selections, and Grouping Geometry explains how SketchUp groups work.
  3. Line up the floor plan with SketchUp’s drawing axes using the Rotate tool () or the Axes tool (). For example, you want the right angles in a floor plan to line up with the red and green axes, so that the SketchUp inference engine makes drawing over your floor plan easy.
  4. Delete extra layers and place the CAD group on a new layer.

    Tip: In Controlling Visibility with Layers, you find an introduction to SketchUp’s layers feature and a video with tips for cleaning up layers in imported CAD files.
  5. Lock the group by context-clicking it and selecting Lock. You lock the group because you don’t want to edit it, but use it as a reference for creating a model in SketchUp.
  6. Adjust the edge styles. This step depends on your preferences, but you might want to turn off profiles in the Styles browser so that all the lines are same width.
  7. Create scenes to toggle layer visibility. Basically, create two scenes where visibility is the only attribute saved in each scene. In the first scene, make the CAD group’s layer visible. In the second scene, hide the group’s layer. See Creating Scenes for details about creating and customizing scene tabs.

    Tip: Although you can also toggle layer visibility with the Layers manager, creating scenes enables you to toggle the views with tabs at the top and close the Layers manager so it’s out of the way.

Building a model from a CAD floor plan

In the following video, you see one workflow for creating a floor plan from an imported CAD drawing. The basic process works as follows:

  1. With the Rectangle tool (), draw rectangles to fill the outline of the building.
  2. With the Eraser tool (), delete any interior rectangle lines, so you have one face in the shape of the building’s outline.
  3. To create an exterior only, use the Push/Pull tool () to create a volume in the shape of the building. Or use the Offset tool () to create exterior walls, and then trace inside each room with the Rectangle tool or other shapes tools to model faces for the interior walls.

The technique shown in the following video illustrates how to use the CAD geometry as a reference for creating a new 3D model of a building, but the basic process is helpful whether you’re creating a new model or fine-tuning imported CAD geometry of a floor plan.

Adding doors and windows to the model

To add doors to a floor plan, you can create one door at the desired height and copy it wherever you need other doors.

For windows, create guides to set the first window at the correct height. After you place one window, copy it, and let the SketchUp inference engine help you place other windows at the correct height as well.

In the following video, you see both of these techniques in action.


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