The new tub I'm installing in my bathroom will be perpendicular to floor joists. The original tub was installed in the same location, but the notch that was cut for the drain and overflow in the floor joist was about 1 1/2" deep. My understanding is that I can't notch any deeper than a little less than 1" (1/6 the depth of the 2x6 joist). What's the best way to approach this situation? I read something about heading off the joist, which would be a pain, since I've already sistered the joist. See included pic.