The Brew Cabin

The piece of clay pipe in the Photo is where the down pipe from my guttering drains into. The downpipe and guttering were completely backed up with all the rain we have had and the pipe just disappeared into the concrete path. I broke away the concrete around the downpipe and found a small piece of angled downpipe just sitting in the clay pipe you can see in the photo.

The clay pipe was completely silted up I have cleaned out as much as is possible and I have had my pressure washer on it but all to no avail - water does not even begin to drain away (I think it is a P-trap) In Cambridgeshire we get a lot of Lichen growing on the roofs and it has had 35 years of this.



I have dug down in the flower bed the other side of the path and found the clay pipe on the way to the soakaway.

I am now wondering whether to cut into this pipe and try rodding it back towards the P-trap so as to avoid damaging the concrete path.(There is no rodding eye anywhere)

My questions are is this the best option if so what do I need to ask for in the BM to rejoin the clay pipe (the inside diameter of the pipe is 3 inches and the widest point of the pipe you can see in the photo is 6 inches)

When I have it cleaned out I would like to fit a hopper will I be able to get a modern plastic one to fit into the imperial clay pipe?

From Sparky

You need to establish that the pipe from this P-trap is serviceable, so, I reckon you're going to have to break into it somewhere, and that might as well be where you've got it exposed under the flower bed.

Rod upstream and downstream to ensure the pipeline itself is not blocked or silted-up. Flush a bucket of water down the P-trap and see if it emerges at the 'break' as a trickle or as a full flow. If the P-trap is silted-up, you might be able to unclog it with the pressure washer now that you have an open point nearer to the unit itself. However, if the P-trap remained steadfastly blocked, then your only option is to break it out and replace with new.

Turning to the rest of the pipeline, you need to make sure it's running clear. The pressure washer will help for the first couple of metres, but what's really needed is a jetting unit, which you'd need to hire in.

The final link in this particular drainage chain is the soakaway itself. Old soakaways have a limited lifespan and they eventually silt up to such an extent that they cease to function. That may be the problem with yours. Only by sending water down the pipeline into the soakaway can you determine whether it's functioning, and, if it is, just how well it's functioning, in terms of litres per hour.
It may be that a new, modern soakaway is required, which means finding a suitable site on your land, digging the pit and installing the soakaway before diverting the existing pipework, but let's take one step at a time, and determine just what is the problem with the existing set-up.

When it comes to re-joining the system where you broke in, then most BMs carry a selection of adaptor couplings that will enable you to piece-in a new section as required. If, for example, you were connecting from the old 4" salt-glazed to a new length of 110mm uPVC, the BM will have a coupling to suit.

Thanks for that Tony

I will let you know how I get on :)

As promised I thought I would let you know how I got on

I broke into the pipe with a large angle grinder and rodded back to the P trap but it was still solid

So there was only one option left to dig a channel across the path about eight inches wide to the P trap I hired a small breaker for the job and this soon made light work of the path as it was only about three inches thick - in the path there was some steel reinforcing under the path was just rubble and soil

I cut the reinforcing out of the way and got down to the pipe which when I removed was full of of concrete and causing silt to back up I guess there since the building was new I replaced with a piece of new pipe after testing the soakaway and now it is working well

I am a little worried about my channel across to my P trap as I believe the house is built on a raft foundation and the reinforcing mesh appears to disappear under the house I haven't dug under the house in any way but I am wondering how to go about reinstating my channel - should I get the reinforcing bar welded back in and then lay my concrete or is such a small area of reinforcing bar missing not a problem and just lay my concrete - is this area known as the apron of the raft ?

Also if you could give me an idea as to what a raft is all about in terms of construction it would be appreciated

Many thanks once again for all your help

This reinforcing steel mesh - is it part of the path concrete or is it part of the raft itself? I'm not quite clear. I doubt it's part of the raft, if it's exposed, as just having rebar steel exposed to the elements (even underground ) does far more harm than the good brought about by having steel within the concrete in the first place. Great care is taken during construction to ensure all rebar is totally encased within the concrete, by at least 50mm.

That's why I ask for clarification - I suspect that, if this steel is NOT part of the path reinforcement, it may just be a bit of 'scrap' steel chucked in the backfill once the raft was constructed.

Anyway, a raft is basically a big concrete slab that spreads the load of a structure over a larger area. They are common in areas with bad ground or where mining is known, hence we get a lot of them here, in what was the Lancashire coalfield. Cutting into the raft is not an easy task, and is something that should be avoided at all costs - this also makes me think that what you've found is not part of the raft.

A raft apron is an access structure, put in place to aid working, but not an essential part of the structure. they are wasteful and rarely used, although some architects use them as 'add-ons for larger rafts when they want to provide for later lightweight buildings, such as a conservatory.

Can you get another photo?

Thanks for the photo....



It's a bit hard to tell but I reckon that just might be rebar from the raft. Best to play it safe and concrete it all in. You can create a joint on the building line, if necessary, and then everything around the gully up to the joint should be concreted - solid concrete, and a reasonable mix such as a C20 equivalent.

On the other side of the joint, where it's just path, you can backfill with decent hardcore or sub-base material, and then lay 100mm thickness of concrete over a small piece of damp proof membrane.

It's really important to ensure you get that steel totally encased once again, otherwise air and water will start to corrode it and then it will start spalling the concrete...I'm not saying the house is in any danger, but it's best to get that steel covered and protected.

If you need any further explanation, or a drawing or concrete 'recipe', just ask. :)

Thanks for that Tony

I've had a look at the concrete page and I'm OK with the recipe for a C20 mix

Thanks again :)