BenL

Thanks @Oz07, they would have worked. Ended up chopping the end then putting the flexible coupler on. Wasn't too much bother.

Makes perfect sense, thank you both. Appreciate it.

Hi all, Hoping for some help. I need to connect a 110 pvc pipe to the original clay drainage. I cant get my head around how to fit as the internal dimensions of the clay pipe look sillmilar to the 110. I used this push fit attachment from screwfix which worked fine and did a nice seal but it reduces the internal dimensions and I ended up with a stuck draining rod as it wouldn't come back through. Nightmare. https://www.screwfix.com/p/mcalpine-push-fit-single-socket-drain-connector-black-110mm/4255v?ref=SFAppShare I cant use an external flexible adapter because of the joining lip on the clay drainage. I'm hoping I'm just missing an obvious attachment. Pictures attached with the temp fix at the moment. Temp fix is taking away the waste but doesn't form a seal.

@jntabbycat came across this thread because I'm looking to build the exact same thing and going through the same issues now I'm at a stage with BC. Curious how you ended up finishing and solving the cold bridge issue on the cross section image. Conscious you posted this a while ago but it's taken me a while to find someone going through the same motions!