I have knocked our downstairs bathroom and kitchen into one. (Don't worry, I have a new upstairs bathroom!) The soil pipe from the old loo goes vertically down through the floor, and then bends to meet the drain outside - I can raise a manhole and see where it joins the drain.
I've made a temporary seal with a sort of rubber bung from B&Q shoved in the top of the pipe - it kept debris from falling down and getting into and blocking the drain. To permanently seal it (don't want any possibility of whiffs or worse coming up into the new kitchen from the drain.) I was intending to pour a bag of 'post-mix' concrete down the pipe, then add water. I'm worried the cementy water will seep through before the concrete goes off and block the drain. I'd be grateful of any advice as to the best way to block the pipe!
TIA
I've made a temporary seal with a sort of rubber bung from B&Q shoved in the top of the pipe - it kept debris from falling down and getting into and blocking the drain. To permanently seal it (don't want any possibility of whiffs or worse coming up into the new kitchen from the drain.) I was intending to pour a bag of 'post-mix' concrete down the pipe, then add water. I'm worried the cementy water will seep through before the concrete goes off and block the drain. I'd be grateful of any advice as to the best way to block the pipe!
TIA