Curtain Systems

BIM for Architecture, Engineering, and Construction Curriculum


In this lesson, students explore techniques for working with curtain walls and the elements that define a complete curtain system—panels, grids, and mullions. They will learn how to:

  • Specify the layout and spacing of the curtain wall elements for new curtain wall systems and how to modify existing ones.
  • Explore the design options available for customizing grid patterns, panel materials, and panel types.

Curtain Wall Elements

Curtain walls provide separation between spaces, but typically do not support structural loads. They are often used to create very sleek, modern exterior skins for buildings or to separate interior spaces where high visibility is desired (for example, between a lobby and a conference room).

Curtain walls are composed of:

  • Panels—often made of glass, but a wide variety of materials can be used
  • Grids—horizontal and vertical divisions that subdivide the wall
  • Mullions—members that frame the panels and provide support for the weight of the panels as well as resistance to wind and other lateral loads

Figure 1.3.1. Curtain system elements—panels, grids, and mullions

Designing Curtain Grid Patterns

Curtain walls are created using Autodesk® Revit® software’s Wall tool and placed using the same techniques as other wall types. The key difference is that you must choose one of the special curtain wall types (which are listed after the basic wall types) from the Type Selector in the Properties palette.

When creating a curtain wall, you can:

  • Create a single wall panel that you will manually subdivide by adding grids and mullions to it.
  • Use a previously defined curtain wall type that specifies the grid pattern and mullion types as part of the type definition.

Regardless of which method you use to create a curtain wall, you can easily modify (add, remove, or move) grids and change the mullions as desired to accurately model your design.

You specify a curtain wall’s horizontal and vertical grid layout (as well as the mullions to be placed at the panel and wall edges) by editing its type and instance properties. You set the pattern for each direction independently, and the layout options include:

  • None—creates no grids.
  • Fixed number—divides the wall into panels of equal size. The number of panels is set as an instance property each wall.
  • Fixed distance—places grids at the fixed distance specified. Smaller panels will be created at the beginning or end of the pattern if the total length to be divided is not an even multiple of the distance specified.
  • Maximum spacing—divides the wall into panels of equal size that are as big as possible without exceeding the maximum specified.
  • Minimum spacing—divides the wall into panels of equal size that are as small as possible but that are no smaller than the minimum specified.

Adjusting Grids and Mullions

You can edit the grid layout of existing curtain walls—adding, removing, or moving entire grids or selected segments—using the Curtain Grid tool.

With the Curtain Grid tool selected, you hover the cursor over the horizontal or vertical edges of a curtain panel, and Revit suggests potential grid locations that would divide it into even increments (for example, halves or thirds). You can also align curtain grids to other elements in your model by snapping to faces, reference planes, or levels.

When adding curtain grids to a wall, you can use placement options to:

  • Add grid lines across all segments (the entire face).
  • Add grid lines to one segment (a single panel).
  • Add grid lines across all segments except ones that you pick to exclude.

Use the Mullion tool to place mullions on any grid line segment, on an entire grid lines, or on all of the curtain wall’s grid lines and boundaries.

To make editing curtain grids and mullions easier, choose an elevation or 3D view that displays the horizontal and vertical grid layout.

Creating and Using Curtain Panel Types

When you create a curtain wall using a type-defined layout or add grids using the Curtain Grid tool, Revit subdivides the wall into curtain panels with the same type properties.

By default, curtain panels are set to a type named Glazed, which specifies a transparent glass material. You change a curtain panel’s type by selecting it and choosing another type from the Type Selector.

You can also create new curtain panel types to model panels with different properties (for example, different colors, materials, or transparencies) by duplicating an existing type and setting the material properties to create the desired effect.

Placing Doors in Curtain Systems

Curtain wall systems behave like basic walls in many ways, but one key difference is that they cannot host standard door objects.

You add doors to curtain walls in Revit by replacing curtain panel elements (which are typically stationary or fixed) with a special panel type that provides door functionality.

Before replacing a fixed curtain panel with a door panel type, you should adjust the curtain grid lines by adding or removing segments to create a panel with dimensions that match the size of the desired door panel.