Solid Element Operations allow you to modify the geometry of one element using the geometry of another. You can add volume, subtract volume, get the intersection of two volumes, or subtract upwards or downwards with a volume.

SEOs make several things that used to be hard easy (true roof thicknesses with nice eaves), and some things that used to be practically impossible possible (differing materials at a slab's perimeter and a hole).

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When you put a regular hole in a slab, the hole edge material is the same as the slab outer edge. This is a problem, since the slab can't clean up to walls of different materials. Using SEOs instead makes it possible to have a different material at a hole. The key is the option for new surfaces of target to 'inherit attributes of operator.'