How to Use Revit Underlay

The Revit Underlay is a helpful feature for displaying all elements from another model level in the current plan view. When working with different disciplines adding an Underlay allows you to understand the relationship of elements at different levels for MEP, construction, and coordination.

The Underlay can be set to any plan view and can be viewed from above or below the current level. By default, elements appearing in the Underlay are displayed in halftone. However, this appearance can be customized using a few options for better display.

In this article, we will look at the basics of the Revit Underlay, how to add an Underlay and customize the visibility.

Revit Underlay

When placing lighting fixtures above furniture in a reflected ceiling plan, the Revit Underlay feature is useful for placing and aligning these elements more efficiently. Vice versa, you can use the Underlay to show up the ceiling plan from within a floor plan. I also use it a lot to see the edges of a roof canopy.

In other words, the Underlay feature shows the relation between model elements placed at different levels. You can set the Underlay in any view where it is required. Revit then displays another level of the model at the view’s cut plane depending on the settings you choose.

The Underlay settings you can choose from are the Range: Base Level, Top Level, and Underlay Orientation. You can view the Underlay from above (Look down) or below (Look up). In both cases, the Underlays appear in Halftone.

revit underlay
Placing Lighting Fixtures in reflected ceiling plan with Underlay

Tip

Discover everything you need to know about the fundamentals of the View Range in Revit, by reading this article: View Range Revit – Everything you need to know.

Add Underlay

Now we know the basics of the Revit Underlay and its purpose, let’s continue by adding an Underlay to a view. In the example below, I use a reflected ceiling plan to position my lighting fixtures and add an Underlay to enhance the visibility of the furniture for better positioning of the lighting fixtures.

Follow the steps outlined below:

  1. Open a plan view
  2. Go to the Properties Browser > Parameter Group: Underlay > Range: Base Level > Select the Level you like to Underlay.
  3. Range: Top Level is automatically set to a Level above the Base Level, but you can adjust it to your requirements.
  4. Change the Underlay Orientation to Look Down (from above) or Look Up (from bottom) > Click Apply or move away the cursor from the Properties Browser.

The Underlay is visible in halftone in the current view.

add revit underlay

For better understanding, here is an image showing the difference between the Underlay Orientation: Look Down and Look Up options.

underlay orientation
Difference between the Underlay Orientation: Look Down and Look Up

Tip

You can easily switch Underlay Orientation for multiple views using View Templates. Learn more about View Templates with this comprehensive guide: View Template Revit – Everything you need to know.

Select Underlay Elements

By default, you are unable to select elements projected in the Underlay. Fortunately, you can change the selection settings to select the Underlay elements. There are two ways to enable the Select Underlay Elements setting. Follow the steps below:

Ribbon

  1. Go to the Select Panel > Click Select to open the dropdown menu
  2. In the dropdown menu, click Select underlay elements to enable
select underlay elements

Selection Toggles

  1. Go to the Selection Toggles in the bottom right corner of the Revit user interface
  2. Click Select Underlay Elements


If the red cross icon is missing from the Select Underlay Elements icon, it indicates the feature is enabled. You can now hover over elements visible in the Underlay to highlight and select them easily.

selection toggles

Revit Underlay Visibility

There are a few options to adjust the appearance and visibility of the Underlay elements. To change the overall visibility settings of the Underlay, follow the steps outlined below:

  1. Open the Manage tab > Settings panel
  2. Click Additional Settings to open the dropdown menu
  3. From the dropdown menu, select Halftone/Underlay > Halftone/Underlay dialog opens
  4. In the Halftone/Underlay dialog, change the settings for Weight, Pattern, Apply halftone, and adjust the Brightness > Click OK when finished.
halftone/underlay settings

By default, Revit applies the halftone setting and shows the Underlay elements in grey. The slider/amount of Brightness makes the lines lighter or darker. To reset your settings to the default configuration in Revit, click on the Reset button in the Halftone/Underlay dialog.

halftone/underlay
Changing the Halftone/Underlay settings

Extra Tips for Revit Underlay

Here are some additional tips for working with the Revit Underlay feature.

  • You can use the Linework tool on Underlay Elements to make them part of the current view. Additionally, if you have an overhanging roof or canopy, use the Underlay and Linework tool to produce projection lines on the current level.
underlay with linework
Linework tool
  • If you are using Phases in Revit in combination with the Revit Underlay, please note that the Underlay elements are not visible in the phases before the element’s completion phase.
  • When creating a PDF or print with the Underlay active, the Underlay elements are printed with grey lines (halftone). You can change the print settings to Replace halftone with thin lines, to make the lines print black.
print settings halftone
Print setting: Replace halftone with thin lines

Wrapping Up

Revit’s Underlay feature helps display all elements from another level in the current plan view. This makes it easy to understand the relationship between elements at different levels for different disciplines. For example, you can effectively position lighting fixtures in a ceiling plan above furniture by using an Underlay.

It is possible to apply the Underlay to any plan view and adjust the orientation to display elements in halftone. Furthermore, the Halftone/Underlay settings allow you to change the Weight, Pattern, and Apply Halftone for enhanced visibility settings. Overall, the Revit Underlay allows you to work more efficiently.

I hope this article helped you understand the basics of using the Revit Underlay feature and how to apply it in your projects effectively. Feel free to leave a comment if you have any questions, tips, or tricks I did not mention.

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