Cut with unattached family instance voids

In Revit 2012, unattached voids in families can be used to cut objects in the project. Here is an example:

Suppose there is an in-place component “counter-top” in the project. You load and place a kitchen sink family on the counter-top. In previous versions of Revit, you can edit the component “counter-top” to create a void geometry and make the sink show well. But if there is another counter-top component of a different shape in this project or in another project, you have to edit the counter-top every time when placing the sink on it. In Revit 2012, there is an easier method to do that.

1. Open “Sink Kitchen-Single.rfa” (or another sink family in the library).
2. Create a new void extrusion. See the image below. (If the existing solid is cut by this void, use Modify tab > Geometry panel > Cut > Uncut Geometry to prevent the newly created void from cutting the solid.)

3.Click Home tab > Properties panel > Family Category and Parameters,and  check “Cut with voids when Loaded”. (See the image below.)

4.Load this family into the project, and adjust its elevation offset to the correct position (you can use the Align tool). See the image below.

5.Click Modify tab > Geometry panel > Cut > Cut Geometry, select the counter-top first, then select the sink. The sink shows well now. See image below. You can load this sink family to other projects, and follow similar steps.

In other cases, for example, you need to hollow the concrete model to lay out the equipment, and schedule the concrete volume. Now in Revit 2012, you can create an equipment void family, and follow the steps above; then the concrete model will be hollowed somehow, and you can get accurate concrete volume when creating a material takeoff. 

Note: The objects that can be cut are: Walls, Floors, Roofs, Ceilings, and family instances of these categories: Structural Framing, Structural Column, Structural Foundation, and Generic Model.