I am remodeling a bathroom on the top story of my house, where the bathroom overhangs the first level by 18". The floor joists in house run east and west, but they installed 4 2x8s (east/west) to support the joists (running north and south) for a portion of the bathroom. I am wondering if I can drill a hole through the 4 2x8 for an 1.5" drain line? The hole would be within the first 1/3 of the overall span of the 2x8s.

Thanks in advance.