In AutoCAD when working in 3D you can check if there is an interference areas where 3D solids intersect, overlap, or occupy the same space or volume. For example you might use it to make sure the fireplace chimney does not interfere with the roof truss framing or that the piping is not going through the HVAC as that is not a good thing to find during construction.

Menu: 3D Operations » Interference Checking
Commandline: INTERFERE

You can use the INTERFERE command to check for interferences within a solid model by comparing two sets of objects or by checking all the solids against one another.

You can also use the INTERFERE command with blocks that contain 3D solids and with nested solids within blocks.

When you use the INTERFERE command, temporary solids are created and highlighted where solids intersect.

If you define a single selection set (one set of objects), INTERFERE checks all the solids in the set against one another. If you define two selection sets (two sets of objects), INTERFERE checks the solids in the first selection set against those in the second selection set.

Once you start checking for interferences, you can use the Interference Checking dialog box to cycle through and zoom to interference objects. You can also specify that the temporary interference objects that are created during interference checking are deleted when you close the dialog box.