plastic soil pipe connection to new cast iron stack

[overlander matt]

As part of the work to convert a room into a bathroom, I plan to install a cast iron soil stack to replace a plastic one and to connect a plastic 100mm pipe to the stack keeping as much plastic out of sight as possible. To do this I was thinking about fitting a T-piece to the vertical stack then a short straight pipe connecting to a 90 deg elbow which should line up with the hole made using a core drill. The question is how to connect the plastic pipe into the cast iron fitting? Has anyone else done anything similar and could share their experience?

Thanks,

Matt

 

[Flyfisher]

There are many adapter options though some of them are rather unsightly if left visible. I've used one of these to connect an old lead soil pipe into cast iron, but only as a temporary solution until I replace the lead pipe . . . . though 'temporary' is currently about 10 years and counting so it's certainly durable
https://www.screwfix.com/p/floplast-underground-flexible-adaptor-110mm/19914

I've also used something like this to connect plastic soil pipework into a cast iron downpipe . . .
https://www.screwfix.com/p/mcalpine-dc1-bl-drain-connector-black-110mm/4255V
. . . though in this case the cast iron pipe went straight up the wall and into the bathroom through a jettied floor, so no T-piece was required.

 

[Craig89]

Hi Matt

I have installed a cast iron stack to plastic underground drainage and plastic into the house. I have a plastic rest bend at the base of the stack that has a small length of male pipe sticking out of it, to this I have then fitted a flexible adapter, similar to that in Flyfishers first link but 110mm straight, to connect to the cast iron. This connection unfortunately is above ground but I intend to hide it by building a small brick pier around it.

Similar situation with the cast iron branch that goes through the brick into the house, that has a small length of cast iron sticking out that then uses another adapter to go back to plastic.

Hope that helps

Craig

 

[Feltwell]

Heresy alert...…

Have you looked at the cast iron effect plastic soil pipes?

I've a very ugly cheap plastic stack to replace here at some point (currently falls into the "ugly as hell but it works!" category of priority). I'd love to use proper cast iron but have the same "connection to plastic above ground" issue, and the cast iron is both very expensive and difficult to fit.

The plastic cast iron effect rainwater stuff is not good at all, I definitely wouldn't use it, but one of the soil ranges I looked at I thought could look OK, with a little tweaking to remove some extraneous moulding & if painted over once installed. It helps here as well that the stack is tucked away around the side of the house.

Edit - just had a look at the two main plastic systems out there, Brett Martin and Floplast. The Floplast one looks significantly better to me, the joints on the Brett Martin system look wrong. I reckon if I used the Floplast system and was careful on what fittings I used, avoiding the boss'd ones, and after fitting I painted it as I would for cast iron, it would take a careful look to tell it apart from the real thing.

 

[steveb]

if the plastic to cast iron joint looks ugly, could you hide it behind a cast iron or an ornate lead hopper ?

Obviously the hopper would be decorative only unless you want an elevated open sewer and I guess what suits would depend on the style of your property and you might need to hack it about somewhat, but it or a similar idea could be used to hide the joint

 

[Feltwell]

A bit of "cast iron porn" for a Friday morning.....

Here's one of this week's endeavours, an old cast iron hopper rescued and installed on my newly repointed porch complete with restored stonework, fed into by a lead overflow detail above.




Alas if you pan out you'll also see the ugly plastic soil stack with it's even uglier connections, gas meter box, boiler flue, knackered cellar window in need of restoration, lots more repointing and brick repairs to do... :lol: :lol: The sheet of OSB is at least only resting against the wall (goes on the ground when repointing to stop mortar stains on the tarmac drive)



I've just shown you the ugliest part of Feltwell Towers! Ahh well, at least *one* bit is done now....... :wink:

 

[steveb]

that looks like you are harvesting sewer gas for your meter there :roll:

you have to admire the craftsmanship of cementing random bricks at random angles into an old lime mortared brick wall - maybe you could paint a brick motif on the OSB and hang it over the pipes when not in use

 

[Craig89]

A quick off topic question but it should help as I will upload a couple of pictures of my stack. What image resizing and hosting sites are people using at the moment. The on I use to used resized it and hosted it all in one which I liked but for some reason now the quality has dropped way off so wondered what sites others are using, even if I have to use an app to resize them first

 

[Feltwell]

you have to admire the craftsmanship of cementing random bricks at random angles into an old lime mortared brick wall - maybe you could paint a brick motif on the OSB and hang it over the pipes when not in use

Yes, there's nothing like real craftsmanship, and whoever refitted the bathroom last certainly knew nothing about real craftsmanship when they put those bricks in :roll: Still, better than in the kitchen where they used expanding foam to replace missing bricks with - externally. Luckily I have a large stack of old bricks and can always find something suitable to replace them with.

OSB painting - creative thinking, I like it...... :wink:

Craig - I used imgbb.com for the pictures above. Seems OK to me but I'm not a heavy user.

 

[Craig89]

I have tried imgbb.com so let's see how these pan out..

My underground waste pipes are very shallow due to the main sewer being relatively shallow that's what my rest bend sticks out of the ground, as mentioned above I will cover it all with some brickwork

 

[overlander matt]

Thanks for your ideas. I probably need to look out the 4" cast iron components that I ordered some time ago (when funds were more readily available) and see how well they fit together in the intended location. I cut a 110mm hole through the wall earlier in the week... I notice the cast iron pipe outer diameter is 105mm but the socket diameter at the end that will align with the 110mm hole is wider. This suggests that the socket will probably have to sit flush with the wall and then accept a cast iron pipe with a connector to the 100mm plastic inside the house. I imagine the adaptor that pushes into the cast iron will have an outer diameter at the end that connects to the 100mm plastic that is too large to be pushed into the hole - is this the reason you went with that approach Craig?

It doesn't seem to exist but ideally there would be a 300mm long fitting that pushes into the cast iron bend that passes through the wall and has a socket on the end to accommodate the plastic pipe.

On a slightly related subject, when it comes to joining the cast iron pipe sections together, what did you use? I vaguely recall a thread on the forum some time ago dealing with this subject...

At the bottom of the stack, I think I have enough fall to accommodate the rest bend and fitting below ground level. I'm not sure the push fitting Flyfisher mentioned is suitable for this as there is a reduction of the internal diameter of the pipe. Any thoughts?

Thanks once again,

Matt

 

[Flyfisher]

On a slightly related subject, when it comes to joining the cast iron pipe sections together, what did you use? I vaguely recall a thread on the forum some time ago dealing with this subject...

I also dimly remember such a thread and I recall there was some discussion about the traditional method being to use rope and lead - but don't quote me on that.

What I'm more sure about is that the plumber who fitted our new bathroom some years ago now used 'Plumbers Mait' for the cast iron soil pipe joints. No problems so far.
https://www.screwfix.com/p/evo-stik-plumber-s-mait-750g/14477

 

[Craig89]

Here is the thread with the installation instructions

https://www.periodproperty.co.uk/forum/viewtopic.php?f=1&t=16720&p=226992&hilit=Lcc#p226992

And here is where I purchased the cord from

https://www.rainclear.co.uk/lcc-cast-iron-soil-caulking-cord-1000mm-transit-primer.html

My branch that goes through the wall, the socket is inside the wall, you have to do that really in order to get the pipe close enough to the brickwork for fixing.

On the branch I installed an off cut of cast iron pipe into its socket and that is what the plastic is then connected to inside as seen above

 

[Zebra]

Love your "beautiful period property detail....not so much" series of photos Feltwell.

 

[JohnArmer]

A bit of "cast iron porn" for a Friday morning.....

Very nice. I've carefully taken down cast iron downpipes and the soil stack for re-instatement: we've got plastic there at the moment. I must get on and do them but there are so many other things to do.

 

[Craig89]

This is how the branch goes into the building. To get it in I removed about 4 bricks and then cut them and reinstalled them after the pipe was in

 

[Feltwell]

Love your "beautiful period property detail....not so much" series of photos Feltwell.

Context is everything

Ahh well, it's a work in progress. If I'd taken a picture of how it looked when we moved in you would also have seen a badly collapsed leaded light window, spalled saturated stonework, stone lintel above the window badly cracked with the remains of old iron fixings sticking out of it, a gas pipe going through the cellar window ( :roll: ), naff plastic hopper and downpipe held in place with duct tape, no lead at the top of the porch, and porch brickwork in a right old state. Depressing that that area still looks cr@p, but hey ho, one job at a time!

I managed to free the opener in the cellar window last weekend without doing any damage, bit of an achievement as I reckon it had been rusted shut for at least 50 years. Oscillating multi-tools are wonderful! Managed to pass an old wood blade through gaps on the edge of the window and slowly cut through the rust. One of the hinges is broken though (I knew that before freeing it off) so I'm going to have a go at welding it, in-situ is the only option - having successfully welded some other cast iron recently. Worst case is I seal it shut again, as it was before.

Anyhow - due apologies to Matt for dragging his post off topic!

 

[fernicarry]

To do this I was thinking about fitting a T-piece to the vertical stack then a short straight pipe connecting to a 90 deg elbow which should line up with the hole made using a core drill. The question is how to connect the plastic pipe into the cast iron fitting? Has anyone else done anything similar and could share their experience?

Had to do something very similar. The old branch had a piece of cast iron pipe coming through the thickness of the wall with the plastic attached to it on the inside with a rubber sleeve contraption held on with jubilee clips. This was a bit of a magnet for debris and we had constant problems with it backing up. None of the below ground drainage was intact either...

Now the plastic goes all the way through the wall into the socket on the back of the branch and its sealed up with lots and lots of denso tape. From the outside none of the plastic is visible. I used a branch with a maintenance panel in case of any further problems but have never had to open it. I figure even if it does leak at least the join is practically external. Still need to point it up and properly seal the spigot on the top, its only been 4 years...

 

[Feltwell]

A bit of "cast iron porn" for a Friday morning.....

Very nice. I've carefully taken down cast iron downpipes and the soil stack for re-instatement: we've got plastic there at the moment. I must get on and do them but there are so many other things to do.

A tip for when you come to clean them up - if you've got or can borrow a decent compressor, a needle scabbler attachment on an air hammer is I've found by far the best way to get old paint and rust off, far more effective than a wire brush. Still a slow, noisy, dirty horrible job though!

 

[overlander matt]

I have enjoyed seeing Feltwell's soil stack - quite a construction!

Thanks for the advice Craig and Alan. I think I will need to cut a larger hole in the brickwork to accommodate the collar of the cast iron bend and then try to join a section of plastic to that - the plastic is a fairly tight fit in the iron. I'm wondering what the best method of joining and sealing is? Given the joint is going to be inside the wall, it's essential that it doesn't fail anytime soon...

I did have the option of running the stack internally in plastic. I'm not sure why I chose to go external other than the original stack was on the outside...