Drilling through joists?
I would like to drill through a 19.5cmx7.3cm joist in my bathroom floor to take a 40mm waste pipe. I know to drill on the centre line (and its just less than 25% of depth) but this joist has 19.5cmx4.6cm joists hung from it at 38cm centres supporting the bathroom floor. I don't want to compromise the whole of the floor strength which will be taking the usual weight of a full bathroom suite. Can I safely do it or do I rethink my waste route?