I am doing a loft conversion on my mid terrace, creating a bedroom plus en suite. The bathroom is under the front slope and needs to drain out of the back of the house. We can get sufficient gradient in the toilet outflow for building regs. However, I want the toilet set into the slope, as it will massively improve the bathroom layout because of ceiling height issues. My builder is strongly recommending turning the loo around to face the slope as the outflow pipe will then be heading in the right direction. Would going with an s trap toilet under the slope be silly?