Ask your local code enforcement official.

What PPF said. Or ask your contractor. Call tomorrow. Done.

Just curious, why do you ask?

I suspect someone is swallowing hard at the cost of the steel needed and thinks that the bigger wood will be cheaper. It won't, ultimately. Done right is always cheaper than done wrong.

do you have an 8' ceiling? you want to install a decorative wood beam in the room? One?

why don't you call your city hall, (or go online) and get residential building code department. ask them.