Please could anyone help,Re-doing the bathroom.The exsisting soil pipe is on the external corner of the house which the toilet goes into at the moment all ok and this is not being moved. But the waste from sink and bath 40mm goes across the internal wall (was boxed in but ugly )to the corner and out in to same soil stack.I am unable to go under the floor as the joists are running the wrong way so!!!! can I drop straight down in 40mm pipe through the floor 2mtrs then through an internal wall then 90degrees through an external wall in to the stack at ground level about 5mtrs in total but a few turns on the way.Would this be ok with venting and the straight fall out of the trap from the bath and basin Thanks in advance Hope i explained it ok