New soil stack - not as easy as I thought...

[Hugh Jaleak]

Keep it simple, you're getting over complicated with that setup. Take that junction off, and rotate the adjustable bend so it points upward. Fit a rodding access into that, (https://www.screwfix.com/p/floplast-push-fit-2-boss-single-socket-access-pipe-black-110mm/82593), then head upwards. It is very unlikely to block in that downward section, but better to have the access and not need it.

I would really advise against fitting that junction there. It is likely to cause you issues with noise and possible blockages, the falling waste will hit that, and splatter everywhere, you want to be directing it towards the sewer! Otherwise, good job done.

 

[ChrisKingston]

Thanks Hugh I've just had another go at it:

I will fit an access point just above the adjustable bend.

I tried to get out the concrete to get right down for a rest bend but it was really hard and grotty and kept nearly pinging the water pipe. Might leave trench open and have another go if I can get rid of the lead pipe.

Thanks for all the help, I'll post a few more pics even it's finished in case any other DIYers taking on something similar. But hoping now out of ground it will be easy!

 

[Hugh Jaleak]

I think given the proximity of the pipe to the footing, you'd struggle to get a Rest bend in anyway, without chopping out a tonne of concrete and coming into the main on an angle as you suggested previously. My only concern with that setup would be, sufficient flow coming from behind the junction to wash any solids that collect, downstream and away.

 

[ChrisKingston]

I put plenty of clips on. Does the pipe or bottom joint need any more support? should I cement them in?

When I fill in the trench again, how much pea shingle should I put over the top of the new pipes?

Only other thing that didn't seem quite right was the final piece with the vent, just push fit doesn't feel very secure.

Would I recommend doing your own drainage to other DIYers? Just about. No bit was really difficult but it's a big dirty job. The trickiest bits were probably:

- cutting into the old pipe, definitely need a grinder with a diamond blade. I had to take guard off the grinder too, although if you have better access you might not need to. As mentioned above, cut a rectangle out of the top section of the pipe

- if you don't have any pipe detector kit then you have to dig the trench very gently without power tools, which takes forever. I did put the spade on a lead water main but was going gently enough not to burst it.

- fitting the top of the vent pipe up an old ladder on a windy day. Lot to carry up there til you get the top clip in. I taped the spirit level to the big top section of pipe before I went up so one less thing to carry.

- if you need to get pipe out of a joint (if you cut wrong length say) you can use mole grips (two pairs roughly opposite each other) tight on the pipe, then hit the end of the mole grips with a big hammer to get the pipe out (though this will probably make this bit of pipe unusable).

Very many thanks for all the advice!