We're having the kitchen done soon and we'll be moving the washing machine into the utility room. Actually, it's a downstairs loo/cloakroom/boiler room which we've knocked through into one single room. We are planning on moving the loo and partitioning it off. The plan is to use the existing connection to the soil stack and just extend the soil pipe inside the house. I'll also need to install a waste pipe for the washing machine. I'd rather not have to drill another hole through the wall as it's over 2 foot thick. Is there any reason why I can't tap this into the top of the soil pipe? If It's OK, then what should I be using, is there a specific boss for this? Obviously I'll need to install some kind of trap to prevent smells coming back up but do I need a non-syphon trap or just a standard U bend? Does it matter what size waste pipe I use (32mm or 40mm)? Finally how long should the vertical pipe be for the washing machine tube?
Thanks.