Diverting a victorian clay sewer

[ali_g12]

Might need some advice or assistance on this one.....

We're undertaking an extension and full renovation of our end of terrace Victorian ground floor flat. This include digging out the cellar to make a utility room and trying to get 2m clear height from a previous 1.7m clear. After breaking out the floor slab and excavating down I've unearthed this fairly large (estimated 6" but I'll get some more accurate measurements shortly) clay sewer pipe. I had a CCTV survey done prior so it wasn't exactly a surprise!

What I gather from the CCTV survey is this is a combined foul and rain water drain (please note the survey below is superimposed onto a the ground floor plan while most of the talking points are sub-ground level). The section in the picture above highlighted in red below:

As this drain runs through my proposed limited height cellar (cellar in blue, below the suspended floor ground level bedroom) I'd like to look at diverting it around from the existing SVP behind the dwarf wall (still inside the house but outside of my cellar area). I note that this would cut off the FWG running from the back of the house. However, this whole area is coming up over the next few weeks during groundworks for the rear infill extension so if necessary we could run a new gully from the back to the existing SVP.

Having read the building regs (approved doc H) I realise that I might be on the limit of my understanding of what is required here. BC are involved in the project so they might need to get involved.

Any advice on regs or practical advice on this would be appreciated. This is how I'm thinking of doing it:

1) Run new 100 or 150mm UPVC from SVP at rear through wall into void between dwarf wall and end of terrace wall

2) Continue pipe run thorugh the void space and through another sleeper wall. At this point it will be unsupported. I see no guidance on running foul/combined drainage through open spaces - does it have to be supported from joists above or supported from below?

3) Join onto exsiting clay pipe from above. I'm not sure how to do this. Can I cut into the existing pipe and 'saddle' from above? Or am I best joining onto the back of the redundant section? Either option is probably going to involve quite a large fall as I'll be dropping the pipe down 2 or 3 foot from the previous sleeper wall section. This is my best attempt at representing that

Looking forward to some advice. Thanks in advance.

 

[blup]

Cant you just move the existing pipe to the edge of tne cellar wall and box in or build into storage cupboards or tne like. The bend shouldn't be significantly increased if at all. Otherwise as you suggest with support for the pipe in as continuous length as possible. BC approval/guidance sought as required.

 

[ali_g12]

Cant you just move the existing pipe to the edge of tne cellar wall and box in or build into storage cupboards or tne like. The bend shouldn't be significantly increased if at all. Otherwise as you suggest with support for the pipe in as continuous length as possible. BC approval/guidance sought as required.

I did consider this approach but need to reroute /replace the old clay one in order to cast a new slab. The cctv drain survey also recommended replacement of this section of the line.

Have laid some 100mm pvc pipe as per my suggested route and now have reached the tricky bit, connecting it all up.

I've got my pvc pipe coming out of the wall and it's 2ft higher than the clay and at 90 degrees to it. The abive section is around 5 metres before the Buchan trap. My research on this site has led me to believe a rest bend into a plastic manhole might be the way to go but I couldn't find any diagrams and suggestions to visit pavingexpert didn't come up with anything.

Any suggestions about specific parts and best practice.

I was also unsure about whether this is Water company property or not. Any ideas? Happy to contact them either way.

 

[blup]

The bend needed for the connection will surely reduce the flow adequately.

Look at Skillbuilder Gosforth Handyman and CharlieDiyte on YT for practical tips on connections and related fittings. There are a few others that will come up,

Maybe if you treated the works as a repair it wouldn’t gone u see building control, I don’t know. If it’s within your property it’s your responsibility not the water companys

 

[cdbe]

Drains (and building inspectors) don't like inaccessible sharp bends. You might be better ditching most of that existing (apart from anything you might need to serve the utility room) and running a new drain externally with new IC's where required. They're always far better in your garden than under your house.

And it's probably better in the "Building" part of the forum.

 

[Hugh Jaleak]

Bit late to the party, but for what it's worth. Pipe can be suspended from suitable brackets/hangers running through voids, key is to ensure adequate and constant fall along the entire run. As with any drainage run, access for unblocking is vital, so assume that has been provided. Will need to be access bends or points in an above ground situation, just be prepared for one unholy mess should you ever need to open them.

If existing clay run is now redundant upstream of where you are proposing to connect the new 110mm run in, then I'd just cut it off, fit a bend looking up, and an access bend at the top looking down, join the two.

This is all assuming Building Control and Water Co. are involved and are happy with what's been done.

 

[blup]

Drains (and building inspectors) don't like inaccessible sharp bends. You might be better ditching most of that existing (apart from anything you might need to serve the utility room) and running a new drain externally with new IC's where required. They're always far better in your garden than under your house.

And it's probably better in the "Building" part of the forum.

View attachment 375841

I think tne OP has all tne pipe in now, just looking for connection advice. He has the option to lay it outside if this all goes pear shape but with an IC at the proposed point of connection is he any worse off keeping the existing run?

 

[ali_g12]

Thanks all for your input. I've got a rough idea of what to do now and managed to source a 180mm to 110mm adapter from Toolstation Flexi clay to PVC . I'm thinking of putting a 87.5 double socket access bend on the pipe coming out of the wall and then come down onto a rest bend that will attach via the above adapter to the cut clay pipe. There will then be a length of around 5 metres to the buchan trap. For context I have put it onto the proposed ground floor layout below ( old layout in red).

Red circle is a proposed IC which will be located within a service cupboard. The existing SVP from floors above and RWG will run into this. The next proposed access point is the access bend just above where it joins on to the back of the clay.

If this is sounds like a reasonable plan I will put it past the BC officer.