Gaining access to soil stack embedded in concrete

[Toilet Duck]

Evening all

I'm looking to convert a smallish downstairs room with a toilet into a wet room. The toilet and sink waste currently exit through a solid wall and immediately join the main soil stack in the kitchen. In order for my plan to work, I need to gain access to the soil stack around 6 - 8 inches below the concrete floor that it disappears into so that I can get enough fall on the proposed wet room waste and join it to the soil stack. The toilet will be re-positioned but use the existing waste pipe as I can hide that in one of those basin/bog units with a cupboard, something like this (first one to come up in a search):



Is there a "best" method of breaking up the concrete around a soil stack to minimise the chances of damaging the actual stack? I was planning on drilling some vertical holes using an SDS drill and once the concrete was weakened switching to a chisel bit. I don't know how far down below the level of the concrete that the stack goes, but I think it must be a reasonable distance.

This is the offending bd now that I have removed the boxing in etc:





Assuming I can remove enough concrete, do I need to fix a proper stack waste t piece or can I use a suitable sized hole saw to cut a hole for the new wet room waste? My concern is that the existing arrangement looks like they joined all the soil stack components (90 degree bend, t piece, main stack etc) and then poured the concrete, so it's now impossible to seperate the existing components, if that makes sense??

Any help/advice etc gratefully received!

[CubanPete]

What about a small pump for the shower waste?

[Toilet Duck]

CubanPete said:

What about a small pump for the shower waste?

I did think about that and did a bit of googling, the majority of what I read suggested they can be problematic but I don't have any experience myself so happy to be proved wrong. They also seem quite pricey for what they are, I seem to recall they were in the £2/300+ range if I am remembering correctly (which I may not be as it was a while ago when I read up). I don't mind going for a pump if it will be the "best" option given the hassle of getting access to the soil stack, but I just thought if I can get a direct waste feed to it then that can't really go wrong, whereas a pump opens up all sorts of possible future issues? If I did go with a pump, I had also planned to hide that in the bog/sink combo cupboard thing as well.

Cheers

[RATATTAK]

From what I can see, I think you have two alternatives. Either raise the floor in the wet room or drain to the foul sewer outside.

[Little Lofty]

You could remove the concrete, cut the soil pipe and fit one of these to take the new waste pipe.

https://www.screwfix.com/p/floplast-sp583g-short-b...

[Toilet Duck]

RATATTAK said:

From what I can see, I think you have two alternatives. Either raise the floor in the wet room or drain to the foul sewer outside.

I can't raise the floor in the wet room unfortunately. I was going to break out the current concrete floor in there to fit the waste etc and then reinstate so that it would end up back at the same level it is now, it needs to stay at the same level for various reasons.

Another issue is there isn't a foul sewer outside, the house has private drainage ie a sceptic tank. The soil stack that disappears into the concrete (I believe) travels under the length of the kitchen floor and eventually reaches the sceptic tank. There is nowhere else suitable to tap into the waste system, it has to be that poxy soil stack.

Nothing is ever simple

[Toilet Duck]

Little Lofty said:

You could remove the concrete, cut the soil pipe and fit one of these to take the new waste pipe.

https://www.screwfix.com/p/floplast-sp583g-short-b...

That's the sort of thing I was thinking about! My only concern is whether or not I'm likely to damage the soil stack by trying to remove the concrete. I know it's a "how long is a piece of string" type question, I just didn't know if it was something that can be done or is best left well alone. If it's a viable option, I wondered if there is a certain way to go about it or just get the SDS chisel on it (carefully!). I have a concrete breaker as well but strongly suspect that would be overkill and more likely than not damage the stack due to the small area in which to work. If the existing stack does break I will be in a bit of bother as it runs under the length of the kitchen floor...

[Little Lofty]

SDS chisel bit on a hammer drill should be ok, soil pipe is pretty tough stuff.

[Spurry]

As you are not on Mains Drainage, make sure that you can still get enough fall on your waste pipe if you wish to put a junction underneath the visible one.

[TA14]

Toilet Duck said:

Evening all Is there a "best" method of breaking up the concrete around a soil stack to minimise the chances of damaging the actual stack? I was planning on drilling some vertical holes using an SDS drill and once the concrete was weakened switching to a chisel bit. I don't know how far down below the level of the concrete that the stack goes, but I think it must be a reasonable distance.

Is that the shuttering on the LHS? If so, dig that out with a wood chisel and then SDS hammer chisel to break out the concrete into the gap. Otherwise start with a 1/4" drill and pepper the narrow part with holes - then open up using larger drills up to about an inch before creating a hole with the SDS and then as before, remove the concrete into the hole.

[pquinn]

You won't hurt the pipe and that sort of screed is usually quite soft compared to a proper concrete and chips out quite nicely. I'd be tempted to have a go at it by hand though to start with (hammer & chisel) rather than jump to the SDS. The risk is you over do it, not so much a risk to the pipe as putting cracks through the floor or drilling in too far.

I've had to chip out around a soil pipe before and the plastic ones are really hard to damage, short of drilling into them.

Then as suggested you can add a 40mm boss.

[Drumroll]

My concern would be that by using the soil pipe you are in danger of getting "toilet" smells coming up from the shower waste pipe.

[pquinn]

Drumroll said:

My concern would be that by using the soil pipe you are in danger of getting "toilet" smells coming up from the shower waste pipe.

Surely you use a trap under the shower? The smells thing is always a risk unless you run the drain straight out to air or have a break in it.

All my drains run into stacks.

[Little Lofty]

Yes, nothing wrong with running it into a soil, that’s what they are for, and that’s why you have a trap.

[Toilet Duck]

Drumroll said:

My concern would be that by using the soil pipe you are in danger of getting "toilet" smells coming up from the shower waste pipe.

My poo doesn't smell

But like others posted, I would use a trap on the wetroom (or any other) waste to stop smells.

Anyway, an update for you all. I went ahead with breaking out the concrete, pictures show the steps I took better than words:

















It actually broke up/came out much easier than I expected. I used a hammer and chisel near the pipe and broke that bit up manually just in case. What has transpired though is the waste doesn't run under the kitchen floor as I was expecting, the soil stack goes into a 90 degree elbow and exits out the back wall, it must then run parallel with the kitchen towards the sceptic tank. This actually works in my favour, as I think it will be much easier to dig up the ground outside and access the soil pipe out there. I can then connect the waste from the wetroom there, I will just run it out the same wall as its in the next room (if that makes sense?). I won't be able to dig it up yet as I have a wild duck nesting in a plant pot immediately outside ( thread here if anyone interested)

Anyway, thanks for all the help!

[RATATTAK]

RATATTAK said:

From what I can see, I think you have two alternatives. Either raise the floor in the wet room or drain to the foul sewer outside.

So essentially it's option 2 above ?

[Toilet Duck]

RATATTAK said:

RATATTAK said:

From what I can see, I think you have two alternatives. Either raise the floor in the wet room or drain to the foul sewer outside.

So essentially it's option 2 above ?

Yes, now that I know it actually runs outside. Gold star for you

[RATATTAK]

Glad you got it sorted