Leaking Cast Iron Soil Stack

[Alz0r]

Hi all,

I'm dealing with a CI stack which is leaking in 2 places

1) is where a builder has used a 110mm strap on boss on a 3 inch soil stack (he packed it out with laminate flooring wedges) for a 40mm bath / sink run

2) at a collar connection further down the stack.

I've just been and wrapped denso tape around the offending areas but I'm still getting water penetrating the tape in tiny droplets (never had that before!) and also it's traveling up the tape and coming out of the top of the wrap.

I'm obviously wary about just cutting away the offending length of CI and replacing with PVC in case the rest of the stack (sited above a shiny brand new conservatory roof) comes down when the weight of the pipe shifts to the rusted pins holding it against the wall.

Can anyone offer some guidance on a remedy that doesn't involve taking the conservatory roof off and cutting the CI down section by section !

Cheers

 

[doitall]

The obvious thing is change the strap-on boss for a 3" CI one and do the job properly.

 

[Alz0r]

Thanks for the reply,

It will still leave the leak further down the pipe tho :/

 

[kevplumb]

take a pic of both leaks

let the dog see the rabbit

 

[Alz0r]

I'm not near the property at the moment, I'm going back this afternoon for round 2.

I will rip off the Denso and replace the bodged PVC strap on with a proper CI one.

This leaves me with the problem of a leaking CI collar. There's a wall bracket on the collar too. Would a rubber sleeve (with jubilees on each end) do the trick? Only problem I can see with that is if the wall bracket is welded to the collar

 

[bathstyle]

It will be if it's an eared coupling.

I'm not too concerned about the Strap on boss leak as any plumber worth his salt can sort than but where on the collar is it leaking?

 

[Alz0r]

On the top -

I was originally greeted by a sticky rubber substance wrapped around the collar, with another strip of lead sheet below that!

 

[doitall]

They don't leak on the top, unless the pipe is blocked.

I would suspect a problem higher up and running down.

 

[Alz0r]

Well just got back from a thrilling day working with cast iron.

Bought a £34 CI strap on boss from Plumbase. But it's too big! 100mm.

I think I'm dealing with 3.5" or possibly 3 inch cast iron. Can't find a supplier anywhere?

Also the builder-come-plumber decided it wasn't worth cutting a proper hole in the side of the stack for his PVC boss, instead he elected to hammer a small triangular shard of cast iron out and then just stick his boss over that with some silicone. If I do manage to source the correct strap on boss, can someone suggest a decent way of turning this mess into a proper hole (there's obviously no anchor point for the drill when using a hole saw)

It's looking more and more likely I will have to cut the whole thing down which just seems excessive just for 1 little connection!

Appreciate any advice,
Alex

 

[Hugh Jaleak]

In veiw of the general condition of the stack from your description id be inclined to talk to your customer regarding replacing the lot. If the top section were to topple and someone was in the conservatory, I think a new roof would be the least of their problems...... The only option I can see to sorting out the current mess, is replacing the offending section with a Timesaver fitting or similar, which means cutting a section from the stack anyway.

 

[JayJay1978]

I'm curious, if you hit a cast iron soil stack with a hammer with the aim to create a hole for a strap-on boss, would it knock out a small peice or would it crack it?

I know cast iron is brittle etc.

Obviously is this case it worked but was he just lucky?

 

[picasso]

he was very lucky

 

[bathstyle]

Cast iron actually drills very easily, I tend to just use a bog standard hole saw.

don't think they do strap on bosses for 3" pipe, it's not listed in my catalogue, only a 50mm Boss pipe which is understandable.

 

[kevplumb]

If I do manage to source the correct strap on boss, can someone suggest a decent way of turning this mess into a proper hole (there's obviously no anchor point for the drill when using a hole saw)

wrap some 1/4 ply over it and mark the centre for the holesaw once it starts cutting it will guide itself