Advice for fixing bodged shower waste drain

[Jimmy2k]

Hi there,

I'm part-way through repairing the downstairs shower room after a leaking plug soaked through the plasterboard wall. I've taken out the plasterboard and prepped the walls with cement-board. The problem I still have is that the waste drain seems to be allowing moisture to soak up through the plaster on the wall next to it, also into the cement floor in the garage on the other side of that thermolite wall.

I've taken some pics of the drain, and also one I think is similar outside. The room is in an extension that was built before we moved in. It looks as though the builders have covered the drain with rockwool and then cement, with the sink and shower waste pipes just placed in the middle.

I spoke to someone who said the drain should have had a vented cover...? The toilet waste drains separately to the left of the pictures.

Basically, is there something I can do to cap-off the drain and prevent the damp rising upwards, or would it be a massive job involving digging up the whole drain?

Thanks in advance.

Outside drain so you can see it without the cement round it. Measures 175x300mm

 

[PhoenixServices]

Very carefully break out the cement, pick any bits out that go down the drain. Then there should be a 4" drain under there. Then fit an adapter that takes two waste outlets, will try and find a link.

 

[PhoenixServices]

Leave the one outside alone.

 

[Jimmy2k]

Very carefully break out the cement, pick any bits out that go down the drain. Then there should be a 4" drain under there. Then fit an adapter that takes two waste outlets, will try and find a link.

Thanks for that PhoenixServices.

I've chipped away the cement and wool. I measured the pipe at the bottom and it does seem to be 4". The other half of the drain that's not chipped away at the moment seems to be like the outside one, with a hard plastic cover - I can chip this away if need be but as it stands one of the shower tray legs will be resting on it.

 

[Jimmy2k]

I can't seem to post URLs but is ToolStation item no. 20648 the sort of thing I need to seal the drain and connect the pipes? Suggestions for the best thing(s) to use would be welcome.

 

[Jimmy2k]

Can anyone help?!

 

[PhoenixServices]

That's a drain plug you don't want that. Chop out the concrete and gulley and fit one of these into the female fitting( if there is one there?) Waste Manifold Black SP588 | Black Pipe & Fittings | NoLinkingToThis check that it is plastic not clay in the floor before doing anything. If it's only one waste pipe fit one of these [DLMURL="http://www.pipescenes.co.uk/upvc-waste-to-soil-adapter-cap-pipe-reducer-110mm-4-to-40mm-1-1-2.html?gclid=CJfhuvjQo8MCFezKtAodOngA6A"]uPVC Waste Soil Adapter Cap Pipe Reducer 110-40mm 4-1.5inch Brown[/DLMURL]

 

[Jimmy2k]

Thanks for that. There's just one 4" pipe opening upwards, seems like terracotta or similar, no plastic at all down there so I'll prob fit the pipe reducer cap you linked and then an adapter to take the two pipes from sink and shower.

 

[PhoenixServices]

You can get that adapter with 2 outlets. Would be better than a tee as will make the other trap gluge. Is there a vent or air admittance valve anywhere on the drain run?

 

[Jimmy2k]

Ok I'll have a look.

I think the drain is continuous with the outside one I posted a pic of above, which has a vent on it. If that's the case would I still need to vent the one inside? The outside drain is approx 15ft away and looks like it runs along to the inside one and then out to the main drain on the street.