Max distance of soil pipe to stack

[Magrah]

Hi all

I have a toilet going straight to the stack. I am fitting a new toilet but the new toilet (on the same wall) is 4.3m's centre of the outlet pipe to centre of the soil pipe. Is this to far? What would be the solution if it is?

Building control have signed of on this already which makes me think its ok but I recall it was 3m.

Also what rake should be used still 1/4" per foot?

Many thanks

 

[doitall]

1-40 ish and you should consider a stub stack and AAAV.

 

[Magrah]

Thanks, its on the first floor so Stub Stack not an option?

Fitting a AAV would not be an issue though.

 

[muggles]

6m is the max building regs will allow, so you're well within that. Fall should ideally be 44mm per metre (2.5º), but it's permissible to go down to 18mm per metre as a minimum. I really wouldn't recommend it on a long run though, you are increasing your changes of blockages

 

[Magrah]

Thanks happy to run 44mm and will use a rodding eye before the run starts. So no AAV needed you think?

 

[doitall]

Thanks happy to run 44mm and will use a rodding eye before the run starts. So no AAV needed you think?

Not in my opinion.

If there's anything else on the pipe it stands a good chance of taking the trap out every time the wc is flushed.

Saying that modern short flushes are less likely to be a problem.

 

[Magrah]

Thanks its only the toilet, toilet is on the wall comes out 90 degree bend then 4.3 meter run to main soil pipe. Another toilet with a very short run connects just above. Not fitted a AAV before but heard a lot about them. assume could be fitted afterwards if there is a problem?

 

[doitall]

Try it you can always add a small AAAV later

 

[DeltaT2]

Thanks happy to run 44mm and will use a rodding eye before the run starts. So no AAV needed you think?

Not in my opinion.

If there's anything else on the pipe it stands a good chance of taking the trap out every time the wc is flushed.

Saying that modern short flushes are less likely to be a problem.

I agree with thescruff, a 'Durgo' type valve or a Stub Stack would be wise & run your horizontal pipe @ 25mm per 1M gradiant. I always try to get the Durgo/Stub Stack at the end of the line. Golden Rule; air behind water when venting soil or waste systems.

 

[Magrah]

Thanks all

So I should continue the run past the toilet put a 90 degree bend in to switch the pipe to vertical and fit an external AAV above the toilet flood line?

On a related note I did not realise that the pipe on the existing toilet (not the 4.3m run) veers down in the external wall so the joint is right where I was going to cut in the new joint for the new toilet. This means two new T's (one on top of another) and replacing the cast pipe for the existing toilet and a much larger section of the cast pipe being taken out (about a 1M whereas before just the size of a T) then before.

The cast pipe is in good condition and does not show signs of any decay. Is it worth it while doing all this just cutting it say 1 ft above where it goes into the ground and changing the whole thing to plastic all the way above the roof line? Or am I just making more work for myself!

Thanks

 

[doitall]

Vent through the roof or AAAV, it can anywhere in the pipe and be boxed in if necessary.

 

[Magrah]

I can't put the pipe in the roof as it comes out of the external wall. But just read you can get external AAV's which is handy and they need to be fitted above the flood line. Only issue this causes is extending the pipe past the toilet externally then diverting it up.

What's your view on replacing the cast or should I not bother?

 

[doitall]

If it's outside why not just stick an 80mm pipe up the wall as a vent pipe.

Why do you need to replace or alter the cast, I certainly wouldn't change it if I didn't have too, and it may be subject to building control.

 

[Magrah]

Thanks a lot, I think that is what I will do. Put a AAV above the flood line run a pipe vertically down which then connects to the soil coming out of the wall and then runs 4.3m to the main soil pipe.

These jobs are never as simple as they seem!

Will leave the cast and just cut in two new T's for the old and new toilets.

By the way all this is through building regs, but must confess mentioned nothing about taking out the whole soil pipe. The building inspector has signed off the work (before its completly complete!) bar an electrical cert. But the point is bar the venting complications the 4.3 run was shown on the plans.

Thanks again all.

 

[doitall]

If you have to cut into the CI a couple of times it may be cheaper to replace, worth costing first.

Can you post a sketch of the proposed pipework.