I believe that modern rustic style is actually becoming a classic style. It's simple, natural and eco-friendly, so will always have an innate appeal. Reclaimed barn boards are a popular and beautiful way to achieve that style.
Reclaimed barn boards are amazingly textured and inherently interesting, and when used in high traffic rooms in our homes - like a bathroom - add an organic element that makes you feel more connected to the earth.
Barn boards on a bathroom vanity, as flooring or in a feature wall in the bathroom can warm up otherwise typically cold and hard finishes like marble, ceramic. glass and chrome, making the room feel more like part of the rest of the house.
Of course, the sustainability benefits of using reclaimed barn boards are also great, since you won't be consuming new materials. If you can find a local builder or maker to provide the vanity or the boards and labour, so much the better. And many times, barn boards are an inexpensive alternative to other vanity or flooring options.
My brother - carpenter, furniture maker and builder extraordinaire - suggests that wood is an overlooked and viable option for the bathroom, but should be used with some simple precautions. "Water and steam in the bathroom can take its toll on wood, so you'll want to protect it. But that's pretty easy using a water-based polyurethane of 2-3 coats all over. Sealing it will do a good job of protecting it from rot. Swelling and contracting may also be an issue, but if you leave a small gap between boards and use flexible silicone caulking around edges where sinks or tubs may connect you'll be fine."
Here are some lovely and simple examples of modern-rustic bathrooms that use reclaimed barn boards. It's really worth considering this option when trying to design sustainably and naturally, instead of purchasing "new" materials.