DIY Doctor UK DIY Forums

I’m currently in the process of converting outbuildings (workshop, toilet, wood store) into a dining room, utility and toilet. I did full plans and got them passed by building control. However the assumed drain line was wrong. The assumption was that the drain went down the backyard which would mean an inspection chamber in the yard. However the drain actually goes under the outbuilding (quite a distance from where the toilet is going – drawings not to scale!) and it would appear carry on that same line into my neighbours (outbuildings were built after the drains).

I think the pictures shows the drain line (Although unless I have actually seen the drain I have called it assumed).

This is the plan I have come up with. Have a stack to the right of the toilet, with an air admittance valve. Plumb the toilet and sinks into the stack. Then connect to the old toilet drain using long radius bends for the two changes in direction. (Unfortunately the old toilet drain is right under where the new toilet wall is going to be, otherwise I could have had my stack there and just one change in direction)

Then if there is ever a blockage I can remove the air admittance valve and rod around the long radius bends? Does that seem sensible? Any help appreciated!

you can install a manhole in the floor for drain access, and fit a recessed airtight manhole cover incase of blockage, rodding will be very difficult from the soil stack.

Thanks for the help. I was hoping I would get away without an internal manhole, but doesn't look like there is any other option. Thanks again.