My post seems to have vanished so I''ll try again.
My kitchen sink connects into the foul drain via a gulley (if that's the right word - it's an open square hole with brick surround at ground level with a U bend below ground). I want to change this gulley connection to one that is sealed. (There will be a conservatory over this area).
To do this properly will I need to have a new stack (venting up high) connected to the foul drain and then connect the sink into the stack? I presume I cannot just make a sealed connection into the drain becuase the sink trap might "bubble" up sewer gas.
Many thanks for your help,
Robert amateur