Damaged cast iron soil pipe

[TedK]

I think my old cast iron soil pipe may be damaged at the point at which it goes underground. The reason I say this, is because I had the floorboards up recently and I noticed that the base of my external wall and the floor are damp also, the section of wall closest to where the soil pipe is sited is constantly very wet, (sorry did try taking pics but they didn’t come out very well due to limited space, rad pipes, cables etc).

I’m thinking of hiring a Kango drill in a couple of weeks to open up some of the patio, with a view to replace any damaged sections of pipe. My question is this, if that the stack is damaged at the joint / bend where it joins the clay pipe, then what sort of connectors do I need to renew this section, given that I’ll be connecting the old cast iron pipe to the newer plastic fittings. I’ve been into the local DIY store and all the drainage fittings appear to be 110mm, and I can’t see how any of these fittings would accommodate a cast iron pipe. Hope this all makes sense.

 

[Hugh Jaleak]

Be prepared if the drain is the old salt glazed pipes you may uncover more than you bargain for..... These can crack, and often leak on the joints, often find it is only the surrounding soil holding it all together! (Which, by this time will probably be wet, black and smelly....)

I would suggest you excavate carefully, and after exposing the drain do not disturb any more than you intend to replace. I doubt you'll find the couplings you need in a DIY shed, you'll need to go to a builders merchants and ask for 'Fernco' couplings, one from 110mm plastic to cast iron, and another to suit the O.D. of the drain. These just slide over either end of the appropriate pipe and have a jubilee clip to tighten and make the seal. You will have to (carefully!) cut the collar off the saltglazed to fit the coupling though. Angle grinder needed for this, and then chamfer cut end to avoid any edges where detritus can catch and block the pipe!!

Just to note, there ideally needs to be a long radius bend at the base of the stack, and any new underground pipe should be bedded in peagravel to protect it before backfilling.

 

[noseall]

Be prepared if the drain is the old salt glazed pipes you may uncover more than you bargain for..... These can crack, and often leak on the joints, often find it is only the surrounding soil holding it all together! (Which, by this time will probably be wet, black and smelly....)

I would suggest you excavate carefully, and after exposing the drain do not disturb any more than you intend to replace. I doubt you'll find the couplings you need in a DIY shed, you'll need to go to a builders merchants and ask for 'Fernco' couplings, one from 110mm plastic to cast iron, and another to suit the O.D. of the drain. These just slide over either end of the appropriate pipe and have a jubilee clip to tighten and make the seal. You will have to (carefully!) cut the collar off the saltglazed to fit the coupling though. Angle grinder needed for this, and then chamfer cut end to avoid any edges where detritus can catch and block the pipe!!

Just to note, there ideally needs to be a long radius bend at the base of the stack, and any new underground pipe should be bedded in peagravel to protect it before backfilling.

Agree with the above but an 87.5 degree rest bend is more than suitable for the stack bottom.

 

[TedK]

Hugh and Noseall, thanks for your advice. Just have a couple of questions, can I use the Fernco fittings underground, as I will be back-filling then probably concreting on top? Also, am I right in thinking that I’ll need a single socket long radius bend / rest bend, to which I attach the Fernco fitting (for cast iron pipe) to the non socket end, followed by a small section of 110mm pipe, then another Fernco connector to the clay pipe?

Thanks again for your time and advice.

 

[noseall]

Personally i would replace the entire stack with a plastic fella.

Fernco couplers are fine underground and were actually designed as a subterranean product.

 

[Hugh Jaleak]

Have to agree with Noseall, be better to replace the stack if at all possible. If not, then either a S/S bend as you describe, or a D/S bend with a short piece of 110mm pipe in either end as required.

Basically you need to avoid using too sharp at bend at the base of the stack, as this can cause problems when the water hits the bottom when an upstairs W.C. is flushed. Something akin to this I had in mind: http://www.screwfix.com/prods/12719/Plumbing/Underground-Drainage/87-5-Double-Socket-Rest-Bend

 

[Nige F]

It could be a nightmare replacing the stack and getting a decent wc connection to an old P trap pan through the wall/ make good etc. - Also if the stack is just for a wc upstairs and no bath/ basin / Kitchen sink wastes go into it - it`s likely a tight radius saltglazed bend will be @ the bottom - change for same radius - Sorry guys but all that long radius stuff is for the Single Stack setup along with deep seal traps and set max lengths of waste run - blah blah

 

[TedK]

Guys, thanks for all the helpful advice. I did think about relacing the stack, but, I think initailly ill have a go at fitting in a new rest bend and connecting it to the old salt glaze. If that fails or goes horribly wrong i'll go for the new stack option. No doubt i'll be back for more of your helpful advice. Thanks again.

 

[theoldun]

Ted. You had some good answers to your post and was going to keep out of it, but then read your very last post.
Cut me teeth on the old LCC stink pipes and salt glazed drainage. Normally we used to set the knuckle bend with the bottom of the collar level with top of path, so either the plumber or drain layer could make the tarred yarn and cement joint above path level.
Used to now and again have problems with this joint after a period of time as the collar used to crack. Old plumber told me due to two reasons.
1. LCC not down tight enough to collar. WC, flush water down stink pipe, splash back up from knuckle bend, over period time soak tarred yarn, good hard freeze collar cracks.
2. Tarred yard and cement joint, LCC on southern elevation, heat on LCC, cast iron, expansion in joint, crack. Slight weepage every time LCC took water..
Some of the old boys who educated me had a mine of information.
Try this before you break out.
If you can see salt glazed collar and joint, wipe it of clean and dry. Run finger hail of thumb round it and if cracked, you should be able to feel it. Flush w.c. two or three times, feel for any dampness round collar and joint.
If you think you have got slight weepage, make up three sided box 300mm square out of lump 25x150mm, timber, or bit of ply, any thing you have kicking around. Place and fix box against wall so that whole of collar and joint is covered. New, repeat New bag cement, half dozen hand falls in clean bucket. Smallest tub waterproofing liquid you can get, mix waterproofer 1 to 1 with water, pour into bucket, mix until the thickness of runny cream, pour into box mould, making solid cube neat cement round whole of joint and collar. Rub cooking oil, any old oil, round inside of box, before pouring in so that shutter strikes clean. Don’t hang about with it as initial set will be very very quick. Throw bit of old well wet sacking or towel over it to stop it cracking or shrinking.
Keep your eye on it for a while to see if wall starts to dry out. If it don’t work, then you have wasted a fiver, but it always used to work for me.
old un.