Now that we have our reference planes all set, we can add our massing. Yes, you can add massing without reference planes, but they just make it much more accurate.
To add reference planes to a model, follow these steps.
1- Open Revit.
2- Open your architectural model.
3- Go to the GARDEN SECTION.
4- On the Massing and Site tab click the In-Place Mass button as shown below.
5- Revit will enable the Show Mass mode. That is fine. Click Close.
6- Call it Garden Roof at the next dialog.
7- On the Draw Panel click the Spline button.
8- Set the Reference Plane to Garden-01.
9- Draw a spline similar to shown.
10- Hit esc.
11- Click the Spline button again.
12- In the Placement Plane menu, select Garden-02 as shown below.
13- Draw another spline.
14- Keep doing this, stepping back through the reference planes.
15- Go to a 3D view. Your splines should look similar.
16- Hold down your ctrl key and select all six splines.
17- On the Form Panel, click Create Form.
18- Click Finish Mass.
19- Your form should look similar to below.
20- If you get a warning that says Mass contains only mesh geometry, which can’t be used to compute Mass Floors, volume, or surface area. That’s OK.