Other than living at a house located at the intersection of a T junction, the other thing that most Feng Shui enthusiast are aware of is, the overhead beam.
In Feng Shui study, the overhead beam is believed to generate downwards cutting (and inauspicious) qi. If you sit or sleep underneath such beams for extended period of time, you may end up with illnesses or suffer relationship problems.
Overhead beams are however a feature of most houses. If you are sitting or sleeping underneath, one all you have to do is to reposition your chair or bed and avoid them completely.
But what if you cannot avoid them? I would recommend that you install a plasterboard (or similar) ceiling to shield the offending beam.
In addition to where you sit or sleep, watch out for overheam beams over your stove and altar. The stove is a very important component of Feng Shui and an overhead beam pressing down on it is inauspicious. The Altar on the other hand is sacred and should be protected.
Another area to look out for it the main door. In some houses I have see one end of the overbeam rest on top of the door frame. This should be avoided.
Overhead beams over locations that are infrequently used, for example the storeroom are not a problem.