To add reference planes to a model, follow these steps.

1- Open Revit.

2- Open your architectural model.

3- Go to a 3D view.

4- Zoom in on the garden roof.

5- Go to the Massing and Site tab.

6- Click Roof by Face.

7- Select Basic Roof Canopy Roofing.

8- Click Edit Type.

9- For Structure Click Edit. See below.

10- In the Material cell in where it says click the […] button.

11- Find Red Fabric.

12- Set the graphics shading to Use Render Appearance.

13- See the image on the next page.

14- Hit OK.

15- Hit OK again.

16- Hit OK one more time.

17- Select the mass.

18- Click Create Roof. 

Your roof should look similar to this!