Wood or steel beam to support a roof ceiling or floor?

There are two criteria for making the decision.

1) How much weight is the beam carrying. Wood beams look great and can carry most residential loads. Commercial buildings often use steel beams to carry the snow wind and floor loads, but heavy timber can also do the trick.

2) How should the wood or steel beam look? If the building is prettier using wood, that might be the way to go. If steel looks better - use steel. Sometimes a combination of wood and steel is perfect.