Trench across concrete floor

[cheeseburger]

Morning folks, thanks for having me.

I would like to move a ground floor toilet across the room to separate it off and create a walkthrough.
The room is about 3m x 3m, concrete (and tiled) floor. The toilet is located at 3 o'clock against an outside wall with the pan connector disappearing vertically into the tiled floor. I want to move the toilet to the corner to the left of 12 0’clock.
This floor is about 40cm above the outside ground level, and the soil pipe about 40cm (to top of horizontal pipe) below ground (i dug a hole to locate it).
For the soil pipe from the desired new location going out and around the outside of the building may just about be possible fall wise but it would seem to me be a lot simpler for me to trench across the bathroom floor deep enough to drop in a straight 2.5m length of 110 with a 1 up and 1 down 92.5 bend on each end and joining to the existing vertical soil below ground.
Is that feasible? sensible? Would there be possible issues going through a dpm? (assuming there is one there).
many thanks in advance.

 

[Ivor Windybottom]

If you want to do this then you should dig to the full depth of the pipe so there's just the one rest bend directly below the new toilet and a straight run to the chamber. Then it's all roddable and you don't have inaccessible likely blockage points under the concrete.

Going around the outside may be more practical. You only need a 1 in 80 gradient. You'll need to dig out to check, hopefully the soil and rainwater pipes will be at different heights so can cross. You should add a chamber on the corner. Place it at 45 degrees to the building, with a 45 on each end and your flow straight through the centre channel. Never use a side branch alone as a 90 turn, as you'd end up with a pile of stinking compost in the centre inlet.

In general, keep everything as straight as possible. Don't add a corner over 45 degrees that can't be accessed. Rest bends are the only exception, they're an extra wide radius bend and are directly below a vertical drop from a flushing loo so won't block.

 

[Scally-Ho]

What about popping a P trap pan through that outside wall and then all the 4" pipework would be outside. I always like the least line of resistance when planning a job.

 

[cheeseburger]

Thank you gents much appreciated. I got a groundworks chap in to have a look and we’ve decided to run the soil pipe around the outside with a new chamber etc on the corner and then on into the existing drains, I just need to leave a soil pipe sticking out the rear wall and he’ll do the rest.
Which leads me to my next question - whats the correct way to connect from left to right w/m standpipe, basin waste and pan to the horizontal soil pipe? I can either surface mount or bury the horizontal 110 about 150/180mm. If the basin and w/m were on the other side of the pan I could just use a boss but unsure what to do when coming from the left.
Thanks again
CB

 

[Scally-Ho]

Run a P trap pan into a branch set to the (almost) horizontal soil pipe and then cap it off to the left with a boss set into the plugging cap. Run your wastes into that boss and ensure you deploy anti vac traps just in case of seal loss should a pull be caused by a strong flush clearing a somewhat impacted blockage in or from the pan.

Branch 110mm 92.5°

To connect various horizontal pipes to a central soil pipe, opt for Aquaflow's branch 110 mm 92.5° fitting. In a complex plumbing system where you have a range of connected fixtures such as sinks and baths or washing machines and sinks, this model is perfect for routing them all to one soil pipe...

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Single Waste Adaptor

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[Scally-Ho]

As an afterthought, there is a neater and less expensive way of connecting internal waste pipe to internal soil by deploying a combined bent pan connector with an end boss for a waste pipe. This method allows 1 1/4" (32mm) waste to connect at the side of the pan without any extra unsightly fittings. Although only allowing a 32mm waste connection, this IMO and experience is perfectly adequate for a W/Mc and a single hand basin teed together. Yes, a W/Mc has a pumped discharge, but 32mm waste is more that capable of handling the discharge

Viva Pan Connector Space Saver with 32mm Outlet

Rigid 90° bend polypropylene WC pan connector with 32mm/1¼" boss adapter, can also be cut to suit and is for use with 4" (110mm) pipe.Manufactured in high quality polypropylene and suitable for all 4"/110mm PVC-U and cast iron soil pipe.• 1¼" top access• Length can be cut to suit• Suitable for...

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[Scally-Ho]

Dont forget when ordering soil fittings to select an access branch for when the soil is put through the external wall. That access plug will save you removing the pan in case of a severe blockage and if the vent pipe rises to near a window, use an air admittance valve to cap the pipe at a suitable height.

Access Branch 110mm 92.5°

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Air Admittance Valve 110mm

Aquaflow's 110 mm air admittance valve is necessary for the prevention of waste liquid expulsion and the build-up of bad odours. When a toilet is flushed or you draw water from a sink, pressure is built up that needs to be released - an admittance valve does this.Designed for indoor use, this...

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