I am nearing the end of a bathroom remodel, and just got my new double vanity in the bathroom. The new vanity is 4-6" higher than the old one, and the waste pipe for the two sinks are sitting pretty low in the new vanity. The only way to fit them would be to notch out the back of the vanity and into the drawer below. I know this is common practice, whether it's "correct" or not, but in my case there's a board running along the back of the vanity that would have to be cut out in order to notch it. This board is one of two boards running across the backside that appear to serve a structural purpose. I'd hate to cut them and compromise the structural integrity of the vanity. On the other hand, I really don't want to open up the wall at this point to raise the waste pipes either. What do you think... safe to notch through that board and into the drawer below?