A bathroom is a damp environment and it won’t necessarily mix with all materials. However, wooden beams can add a lot of character and it would be a shame not to include them in the design of your bathroom if this is something you want to do.
The main thing to remember is to use the right type of wood. It should be dried rather than green, as this will prevent it from shrinking and no longer fitting into the space. Discuss the right type of wood to use with the retailer, as they will be able to give you plenty of advice about the different types of hardwood and softwood beams.
You can also treat beams to give them a different appearance. It may also help to protect the beams, depending on the type of treatment you use. If not, natural wood beams will also look lovely in a bathroom setting.