I'm looking for some detailed info, preferrably some diagrams for the following...
House has downstairs wc, directly below upstairs bathroom, which has bath and sink but no wc. Downstairs toilet drains down into floor, out through back wall (underground) and into sewer pipe. There is no inspection chamber in the garden.
I need to add a toilet upstairs via an external stack. I'm also thinking of connecting the downstairs toilet to this new stack, out through the back wall and blocking off the current underfloor connection. This is mainly because adding new pipework (for both toilets) would be easier than trying to tap into the existing underground one that goes to the downstairs toilet (I think?).
I then intend to excavate down to the existing branch (in the garden) and install an inspection chamber, at that junction, while at the same time, renewing the branch that goes into the sewer.
So, I will renew everything from the sewer, back to the house, to supply the old and new toilets (and possibly kitchen sink and dishwasher).
Should I decomission the current branch into the sewer, from the house, and block it up with cement, making the new branch on a straight bit of the sewer (away from the current branch)? Or should I make use of the existing branch and put an IC in at that location?
Or, would it be possible to do this without using an IC and just connect the new stack onto the existing branch at the back wall, before it goes under the house and into the downstairs wc?
I'm familiar with the technique for tapping in to a sewer and adding a branch, but I could do with seeing some diagrams that depict the system, dimensions and materials etc. (Haven't yet found anything on Google... not sure on the correct search query string(s).
I'd be grateful for any advice.
cheers, deano.