Waste pipes etc

[Olivias Grumpy]

Hi
Advice please?
I’ve had a continual problem with a bath to soil stack leak

40mm Waste is running beneath floor to an internal stack and connected via a strap on boss. Despite best efforts it leaks between adapter flange and soil pipe
I’ve now damaged soil pipe and will replace the section from bathroom vertically down into kitchen and then into the ground
At the bottom of the soil is another strap boss which takes the kitchen sink and matching machine Waste. No problems at the bottom end.

Because all bath Waste pipes in bathroom are below floor I’m limited for where I can connect to soil to maintain a decent fall.

Therefore I’m concerned if I replace like for like with anothe strap boss I may end up with a similar issue in the future

My question is could I run 40mm Waste down alongside soil pipe inside and tee into 40mm kitchen Waste ?
Or would that give a different problem back through kitchen/washing machine waste?

Cheers

 

[Newboy]

If you're replacing the stack pipe then add a boss connection rather than using a strap boss.

https://www.screwfix.com/p/floplast-sp581-boss-pipe-black-110mm/97309

 

[Olivias Grumpy]

Cheers for reply

I’ll measure up etc
The position of the connection is important above ceiling is important obviously for the fall
I can try and use boss as suggested but it has to connect directly to the branch above for the toilet. This in turn puts the boss connection in a fixed height.
That was why I used a strap on as I could position the 40mm connection at correct height

I must admit I’d rather use the boss connector you’ve suggested as the only possible leak then is the rubber adapter itself

One way or another it’ll be done today

Cheers

 

[John D v2.0]

My question is could I run 40mm Waste down alongside soil pipe inside and tee into 40mm kitchen Waste ?

No because stack/vertical pipes must be 50mm
You could take it down in 50mm then into the stack as 50mm, and connect the 40mm washing machine into thet. But it seems a bit overkill 2 stacks in parallel unless there's no other option.

 

[Olivias Grumpy]

Thanks John D
I did think that may be the case
I’ll get around it from within the bathroom.

 

[Olivias Grumpy]

If you're replacing the stack pipe then add a boss connection rather than using a strap boss.

https://www.screwfix.com/p/floplast-sp581-boss-pipe-black-110mm/97309

Re worked the pipes
I used the boss pipe as suggested although I had to lower it by 110mm
I cut down the removed stack pipe and made a short extension
I inserted it between the toilet branch and the new boss stack

Much better job and peace of mind

Cheers

 

[Newboy]

Thanks for the feedback - good to know it worked out ok