Plumbing & Drains For New Extension - Advice Needed Please

[HHHamsta]

Hi All, I'm due to start building a new side extension on a 3 bed semi, it's across the driveway up to the boundary. We're adding a downstairs toilet and utility room. The existing soil stack will be retained and boxed in with added rodding eye as it's well positioned for the existing 1st floor bathroom and a new on-suite on the 1st floor will also back onto this. As we are going up to the boundary we don't have an option to move this externally.

We have build over agreements and planning etc. I need advice if there are any possible issues or considerations with the below layout please, plumbing for the utility and bathroom will be above ground feeding into a 110mm adaptor behind the toilet with AAV hidden in the wall (with ventilation).

Also, do you have any suggestions for how best to detail the connections behind the toilet please? The floor will be block and beam, insulation, concrete.

Thanks in advance.

 

[ShaunCorbs]

I would want another 110mm point by the washing machine / sink eg utility

 

[Ben-gee]

Are you having a sealed internal manhole for where your 4” joins the main sewer run?
I presume there is an external one currently?

 

[HHHamsta]

Are you having a sealed internal manhole for where your 4” joins the main sewer run?
I presume there is an external one currently?

There is an external manhole currently which we're removing and piping straight through, any external access will be from the adjoining property, the water company are happy with it as issued the build over agreement. I don't think they allow internal access covers any more and from some of the stories I've heard when they back-fill I'd rather avoid!

In the rare event of a blockage, the rodding points would be via the AAV or rodding eye on the existing stack.

 

[HHHamsta]

I would want another 110mm point by the washing machine / sink eg utility

Thanks Shaun, what's the reason for this please? I could swap the toilet and sink around to share the same drain connection as the utility, would this provide a benefit?

 

[ShaunCorbs]

That would be better as you have max runs on waste pipes etc

And I would pipe in separate eg one pipe from toilet sink 11/4 and an 12/2 from the washing machine and sink etc

 

[Murdoch]

Just bear in mind the LABC officer will have their views ….

 

[HHHamsta]

Just bear in mind the LABC officer will have their views …

Whats the science behind a Y junction being harder to clear if it has rodding access, is it because you only have access from one end?

 

[Murdoch]

Whats the science behind a Y junction being harder to clear if it has rodding access, is it because you only have access from one end?

the inspector will want to see the runs along with the foundations before they are poured ….