Do I need to treat my wooden beams?

Yes. It's always a good idea to treat all wood, especially in high moisture environments like kitchens and bathrooms. Moisture can get into the grain of the wood, make it swell or contract and at the very worst cause fungal episodes such as mould. Even central heating can make wood dry out which leads to cracking and warping. Application of an oil or wax every 2-3 years can maintain a seal and keep your wood looking it's best.