Building Envelope

Building Envelope


In this lesson, students will explore how to use the Autodesk® Revit® Architecture software to place and work with the elements that compose a building envelope. They will learn how to:

  • Model wall types and design features.
  • Create new wall types and edit their structure.
  • Place and adjust the properties of doors, windows, and wall openings.
  • Create roofs with different shapes and slopes.

Modeling Walls Types, Structures, and Design Features

All walls placed in a building model have a wall type associated with them. The wall type includes a definition of the layers and materials that determine the thickness of the wall, so choosing the correct type for every wall is very important for creating accurate building models.

As you place new walls in your model, Autodesk® Revit® software automatically chooses the same type as the last wall created. You can accept this type or choose a different wall type using the Type Selector. You can also change the wall type after walls have been placed, but it is typically more efficient and better practice to choose the proper wall type as you place new walls.

You can create new wall types to model materials and wall assemblies that are needed for your design. And you can specify settings that determine the height of the top and bottom of the wall in the Properties palette.

Placing Doors, Windows, and Wall Openings

In Revit, doors, windows, and wall openings are modeled as components that are hosted by walls. You place these elements by opening the Door tool, Window tool, or Wall Opening tool, and then placing the component in a wall that has already been modeled.

While they are similar in many ways, the specific pieces contained in each type of component differ slightly because they include unique parts needed to perform their architectural functions:

  • Door components cut an opening in a wall, which is filled by a door frame and one or more swinging, sliding, or folding door panels. Many door types also include interior and exterior trim.
  • Window components cut an opening in a wall, which is filled by a window frame and one or more swinging or sliding sash panels. Many window types also include interior and exterior trim.
  • Wall openings cut an opening in a wall, but include no panels or other parts to fill the openings. Wall opening components are also available in the Revit Library to create nonrectangular shapes, and some components include trim.

You can change the sizes of doors and windows by choosing different types in the Type Selector or duplicating an existing type and changing its dimension properties to create a new size.

Doors and windows can be placed individually, or you can use arrays to quickly place many components using an even spacing. All of the elements in the array will be identical to the first and be spaced evenly along the length of the array.

After placing a door, window, or opening, you can adjust its:

  • Horizontal placement—by dragging the element along the wall or adjusting the temporary dimensions to precisely place it.
  • Vertical placement—by adjusting the Header or Sill height properties.
  • Orientation—by selecting the element and clicking its control arrows to flip the exterior and interior sides.
  • Hinge side (for doors only) and swing—by selecting the element and clicking its control arrows to change the location of the hinge and the direction that the panels swing.

Creating Roof with Different Shapes and Slopes

The Roof by Footprint tool in Revit enables you to create roofs with many different shapes and forms by sketching or picking the roof boundary and specifying which edges of the roof should create sloping roof planes. Using this tool, you can create model the common roof shapes typical of most architectural styles, for example:

  • Hip roofs—all roofs edges are slope-defining.
  • Gable roofs—some roof edges are not slope-defining, and gable end walls appear at these edges.
  • Shed roofs—one roof edge is slope-defining.
  • Flat roofs—no roof edges are slope-defining.

You can also build up more complex roof shapes by creating several independent roof elements to model gambrel roofs, mansard roofs, clerestory roofs, and dormer roofs. Where the edge of one roof intersects the face of another roof, you can join them to automatically determine the geometry of the intersection.

Revit also provides a Roof by Extrusion tool that enables you to create roof surfaces by extruding a surface from a sketched roof profile. This tool provides great flexibility for creating roofs that cannot be defined using simple sloped planes, for example a curving roof or barrel vault.

Learning Objectives

After completing this lesson, you will be able to:

  • Understand the methods for changing wall types and for creating new wall types with specific structures and design features.
  • Appreciate the techniques of placing doors and windows both in regular patterns and with appropriate height properties.
  • Explore methods for creating simple and complex roof elements modeling a variety of roof shapes and forms.


Modeling Wall Types, Structures, and Design Features

In this exercise, you will learn how to:

  • Edit a wall's constraints and instance properties.
  • Define a wall's structure and adjust the material wrapping settings.
  • Add design features to a wall, such as sweeps and reveals.
  • Use and modify stacked wall types.
  • Edit wall boundaries to create custom shapes.
Figure 1.2.1 -
Figure 1.2.1 - Regular walls and stacked walls with edited boundaries
Video Tutorial
Student Exercise
  • Select and Change the type from Generic – 8" to Exterior – Brick.
  • Create a new wall Type called Wood Panel Wall and specify the following structure starting from the exterior side:
    • Finish 2 [5] layer of Horizontal Panel Wood with 1/2" thickness. This layer wraps.
    • Structure [1] layer of Stud Layer Wood with 1 5/8" thickness.
    • Finish 2 [5] layer of Horizontal Panel Wood with 1/2" thickness. This layer wraps.
  • Change all the interior walls to this new wall type Wood Panel Wall.
  • Also change the exterior living room walls indicated on the Ground Floor plan view with the text annotation Panel to the Wood Panel Wall.
  • Open the default 3D view, and select the interior walls that protrude through the roof. Attach these walls to the base of the roof
Figure 1.2.2 -
Figure 1.2.2 - Residence with newly specified interior and exterior wall types

Adding Doors, Windows, and Wall Openings

In this exercise, you will learn how to:

  • Add doors and windows to a building model by choosing their type and placing components in host walls.
  • Change door and window placement.
  • Change door and window height properties.
Figure 1.2.3
Figure 1.2.3 - Placing windows and setting their properties
Video Tutorial
Student Exercise
  • Open the plan view of the project model and zoom in to focus on the living room area, which features a row of doors on the east side and a row of windows on the west side.
  • Change the view’s display style to wireframe so you can easily see the underlay drawing indicating the locations of the doors and windows to be placed.
  • Place a Double-Glass type door at one end of the east wall, and then array it to create three instances as shown in Figure 1.2.4. Use the underlay drawing to determine the position of the first door you are placing, and use the width of the door as the distance between elements of the array.
  • Create a similar array of Casement Dbl with Trim type windows in the dining and bedroom areas as shown in Figure 1.2.5. Use the underlay drawing to determine the position of the first window and use the width of the window as the distance between elements of the array.
Figure 1.2.4
Figure 1.2.4 - Arrayed doors in the living room area

Figure 1.2.5 - Arrayed windows in the dining area

Creating Roof Shapes

In this exercise, you will learn how to:

  • Create roofs by specifying their footprint and adjusting their properties.
  • Modify a roof footprint and slope-defining edges to fine-tune the shape and create various roof shapes and forms.
  • Create a custom roof form by extruding a roof surface from a sketched profile.
Figure 1.2.6
Figure 1.2.6 - A roof created by extruding a surface from a sketched profile
Video Tutorial
Student Exercise
  • Create a new roof by footprint over the triangular main living area of the project model. Trace the red model lines in the Roof – Living & Bedrooms plan view as the boundary of the roof and specify that all edges will be slope-defining. The slopes to use are indicated in the text annotations on the view.
  • Create another roof by footprint over the southeast bedroom wing by tracing the green and blue model lines in the plan view. All edges of this roof should be specified as slope-defining, except for the green boundary (as this edge will be joined with the living area roof). The slopes to use for each edge are indicated in the text annotations.
  • Join the non-sloping edge of this bedroom area roof to the closest face of the living area roof to create a single roof as shown in Figure1.2.7.

Figure 1.2.7. Roof composed of several joined roof elements


Modeling Wall Types, Structures, and Design Features

  • How is the total thickness of a wall type computed?

The total wall thickness is determined by adding thickness to each of the different layers that make up the wall assembly.

  • How can changing a wall’s type affect the clear space between adjacent walls?

Changing a wall’s type typically changes the wall thickness, and this can change the space available between adjacent walls. Where the thickness will be added depends on the location line setting of the wall.

  • In a typical residence, what locations are most critically affected by the wall thickness?

Narrow hallways, closets, bathrooms, or anywhere where the space provided is close to the minimum clearances required.

Adding Doors, Windows, and Wall Openings

  • Do the doors and windows move with the walls?

Doors and windows will automatically move when their hosting wall moves.

They can also move within a wall if constraints have been set up that link their position to other objects (for example, intersecting walls or nearby doors or windows).

Windows do not change location if the wall length or height is resized.

  • Do doors and windows automatically adapt to the thickness of the host wall?

Yes. The elements (frames, jambs, sills, and so forth) of the door and window components typically resize themselves based on the thickness of the hosting wall.

  • What happens if the boundary of the door or window exceeds the extents of the wall?

Generally, Revit will allow you to place doors and windows as long as the placement point―typically at the center of the window―is within a wall.

If a wall is a resized such that the placement point falls outside the new boundary of the wall, Revit will report an error saying that it cannot cut the wall opening and will remove the window.

  • Can you place a door at a height above or below the associated floor level?

Most doors offer a sill height instance property that enables you to specify an offset above or below a floor level.

Creating Roof Shapes

  • What would be the method for creating a barrel vault roof?

Barrel vaults are best modeled using a roof by extrusion. The profile can be sketched as an arc or semicircle, and then extruded to form the length of the roof.

  • How about a dome?

Dome roofs are more difficult to create. One strategy is to create an in-place component that revolves an arc segment around a vertical axis. Unlike roof by extrusion, the profile to be revolved must be a closed loop indicating the thickness of the roof.

  • How would you model a sloping roof surface surrounding a lower flat roof—a strategy often used to conceal utilities and mechanical equipment?

This sloping roof form could be generated using roof by footprint, specifying two boundaries―the outer and inner edges of the roof. The outer boundary is typically specified as slope-defining, whereas the inner boundary is not, to create roof planes that slope up from the exterior.

  • What can you do if Revit reports that it cannot create a roof by footprint using the boundary sketched?

When Revit reports that it cannot create the roof by footprint, this indicates that geometry specified in the sketch and slope configuration is physically impossible to create. First create a simpler shape (with fewer slope-defining edges and equal eave widths) and then iteratively edit the boundary sketch to add in complexity and details.

Key Terms

Key Term
Stacked Wall
A wall that has two or more horizontal layers, each consisting of different materials and surfaces.
Wall Sweep
A horizontal or vertical projection from a wall, often decorative in nature. Examples of wall sweeps include baseboards and crown molding.
Solid geometry that turns (revolves) around an axis. For example, you can use the Revolve tool to design a dome roof, a column, or door knobs.
A decorative cutout in a wall.
Slope Defining
Characteristic referring to a roof edge’s role in defining the roof slope.