Cast Iron end bit rusty - About to get covered by concrete

[kavehh]

Hey everyone,
I'm covering the damp line of my flat with concrete since previous owner got rid of it for aesthetic reasons. The part that was in contact with concrete looks really rusty and weak.

The pipe will be covered with concrete on Friday. My questions are:

1) Does the pipe looks ok to you? Will it survive in the concrete for years to come ? or it'll give up

2) Is there any spray, felt or sleeve I can use to extend the life of it?

3) If you are suggesting for me to change? would you please list all the items I need in order to change the pipe on screwfix or toolstation? I have angle grinder. There is already a sleeve underneath it.

Thank you for your help

 

[Tigercubrider]

Do you mean the damp course?
If you cover that, it will lead to a damp flat.
Paint the pipe with an anti rust then some external paint.

 

[HERTS P&D]

There has been a repair to that stack, you can see a fernco coupling on the 3rd picture. I would want to know what was repaired and the condition before covering with concrete.

Andy

 

[Hugh Jaleak]

+1 for above. Looks to be a fairly short run from the stack to the chamber, assuming it's not ridiculously deep, I'd excavate (carefully) and ascertain the condition of the pipework below ground, particularly the rest bend and pipework up to the base of the stack, before burying it in concrete. Better to repair/replace now, than have dig up at a later date to repair.

For belt and braces, replace to above ground level with Plastic, leaving you the option to couple straight to it at a future date should you need to replace any more of the Cast.

To do so, you'll need a https://www.screwfix.com/p/floplast-underground-flexible-adaptor-120-136mm/19914 to go from clayware to plastic, a rest bend, https://www.screwfix.com/p/floplast-push-fit-87-5-double-socket-rest-bend-110mm/12719, some 110mm pipe, and a suitable connector back to cast, possibly another of these https://www.screwfix.com/p/floplast-underground-flexible-adaptor-120-136mm/19914.

Pipework will need to be bedded in peagravel then once set, haunch with peagravel, and select backfill for initial layer, no lumps or stones that could potentially damage the pipe. If shallow, just concrete over it.

 

[JohnD]

What do you mean by a "damp line?"

What do you think is its purpose?

What advantage do you hope to gain by covering it with concrete?

 

[kavehh]

Thank you everyone for the responses. I found a photo of the concrete when it was in place. Reasons I'm doing the concrete is first:
1) prevent mouse from entering the flat. they dig right next to the wall and tunnel their way. I used mesh wire and it prevented them from entering. Now I just want to cover it with concrete for a cleaner job

2) Damp course, my apologies. I guess it prevent water from going directly underneath the flat if i build the concrete and aim it away from the flat. That's how the flat used to look like.

3) Regarding the waste pipe. the sleeve you see at the bottom is from the previous work. All pipes were changed underneath to plastic. It's just the small bit I'm concerned about. Shall I buy some anti rust spray and paint it over or it's better to change that section before pouring concrete?

4) Lastly the area i'm putting concrete is 410x40x10. I bought 5 bags of cement and 25 bags of ballast. I'm putting 5cm of Type 1 underneath. I feel like I'm over estimating it but order already on the way. Also getting a small vibrating plate to firm up the ground.

Thank you everyone. I wish I could contribute somehow to this wonderful platform.

 

[JohnD]

You must not bridge the DPC with concrete.

Your finished level of ground or paving must be two bricks or more lower than the DPC

Usually this is achieved by digging out the ground to reduce its level before laying the paving.

Your old drain has previously been repaired. This is typically because the old fired clay pipe or gulley is broken or cracked and leaking into the ground. It is not possible to tell from your photo how satisfactory the repair is, but rather than concreting over it (and making future repairs more difficult and expensive) you should cautiously excavate round it, perhaps with a garden trowel, until you can inspect it. If you haunch round it with shingle instead of concrete it will be able to move slightly without breaking.

The rusty cast iron is worse than I have seen after a hundred years. This might have been accelerated by long term leaks in the ground. It might need to be replaced. If sound, you can wire-brush to clean metal, apply a rust-killer such as Kurust followed by a metal-protective primer and oil based gloss paint system. Hammerite is sometimes used but unsuitable because rust can grow under the paint film, and it is very difficult to strip off or recoat. It would be very preferable to replace with new.

If you have gaps in the wall, this is common where long-term leaks have washed away lime mortar. You can expose the brickwork, wash out the joints with a waterjet, and repack with cement mortar. You do not need to use lime because underground brickwork does not "breathe".

 

[kavehh]

You must not bridge the DPC with concrete.

Your finished level of ground or paving must be two bricks or more lower than the DPC

Usually this is achieved by digging out the ground to reduce its level before laying the paving.

Your old drain has previously been repaired. This is typically because the old fired clay pipe or gulley is broken or cracked and leaking into the ground. It is not possible to tell from your photo how satisfactory the repair is, but rather than concreting over it (and making future repairs more difficult and expensive) you should cautiously excavate round it, perhaps with a garden trowel, until you can inspect it. If you haunch round it with shingle instead of concrete it will be able to move slightly without breaking.

The rusty cast iron is worse than I have seen after a hundred years. This might have been accelerated by long term leaks in the ground. It might need to be replaced. If sound, you can wire-brush to clean metal, apply a rust-killer such as Kurust followed by a metal-protective primer and oil based gloss paint system. Hammerite is sometimes used but unsuitable because rust can grow under the paint film, and it is very difficult to strip off or recoat. It would be very preferable to replace with new.

If you have gaps in the wall, this is common where long-term leaks have washed away lime mortar. You can expose the brickwork, wash out the joints with a waterjet, and repack with cement mortar. You do not need to use lime because underground brickwork does not "breathe".

Hi John.

I believe it is,
The damp course is the black part which finishes where the exposed bricks starts. It used to be covered in concrete in past. It needs to be filled as mice will find their way in and it seems like all the water goes directly underneath the flat. Am I wrong ?

I’ll wire clean the pipe with wire brush, apply some protectors. I doubt I can change it without messing it up I’ll concrete around it in case it needs to be changed. Any recommended gap between concrete and the pipe ?

 

[JohnD]

The black paint is not the DPC. It is an attempt to hide (it does not cure) damp at the foot of a wall. In your case the historic damp may have been caused by the leaking drain.

In fact it makes the damp worse, by blocking evaporation.

The real DPC will be a layer of slate in a mortar bed two bricks above where ground level used to be when the house was built. Once you have found it, it will be at the same height all round the house, unless you are on a steep hill. It is usually directly above or below the airbricks, and may be easier to see beside or below a doorstep. Your ground or paving level should be dug out to restore the correct gap, and avoid damp

The strip at the bottom of the cement plinth is probably a metal beading, used to neatly make the bottom of the plinth. It may, or may not, coincide with the DPC. Plinths should not cover the DPC because this allows damp to bridge past it. Cement plinths are usually very hard and difficult to remove, though they can be grooved out to expose the DPC.

Round the pipe, you could leave a square gap in the concrete the size of a paving slab. You can fill this with shingle. If you want, you can get a paving slab, drill and notch it to fit round the pipe, and cut it in half so it can be lifted in and out. This will be easier to keep free of weeds.

 

[kavehh]

Hi John.

I believe it is,
The damp course is the black part which finishes where the exposed bricks starts. It used to be covered in concrete in past. It needs to be filled as mice will find their way in and it seems like all the water goes directly underneath the flat. Am I wrong ?

I’ll wire clean the pipe with wire brush, apply some protectors. I doubt I can change it without messing it up I’ll concrete around it in case it needs to be changed. Any recommended gap between concrete and the pipe ?

Thanks

It makes sense. Any solution you’d suggest ? I need to cover it somehow but as you suggest keeping a gap to the wall. Shall I put a drainage?

I believe bottom of black part is my damp course.

I just got the delivery to start the job.
I can’t keep it exposed as mice will find a way in.

Thanks

 

[JohnD]

I think you should clean out and remortar any gaps in the wall. If mice are getting in they must be quite bad. Is it round pipes or something? Broken airbricks?

 

[Tigercubrider]

Mice don’t gnaw though brick . But they can go through any hole that a pencil will.
You’d do better to mouse proof using stainless mesh than concrete.
If you have tunnelling rodents they could be rats.