The simple answer: Create a location over the buildings, but uncheck the boxes that apply the location to high ground, low ground, etc... Then just preserve a trigger that kills all buildings at that location.
The better answer: Often times when players lift buildings they do so in error, or just to see if they can -- it isn't clear that they shouldn't lift the buildings. Therefore, it's unfair to destroy that building for the player, because it puts them at a disadvantage they might not have anticipated when they lifted the building. To eliminate this disadvantage, do the following: Follow my first answer, but create an additional location with the same elevation properties. Now, the triggers for the two locations should look like this:
Location 1: If a player brings a building to location 1, then center location 2 on all buildings owned by that player at location 1.
Location 2: If a player brings an engineering bay to location 2, kill all engineering bays for that player at location 2 and then create an engineering bay for that player at location 2.
Repeat the second trigger for all liftable buildings. This essentially recreates the building that was lifted and destroyed.