Big Hole Under Kitchen Sink

firsttimebuyer2013

So bought first home and have ripped out the kitchen. The sink waste pipe was leaking and clearly has been for some time. Pulled out a baking tray full of stagnant water and the smell was horrendous.

Anyway, after getting out the sink and the cupboard, I discovered this hole about 1ft square. It's probably 5 or 6 inches deep. The waste pipe goes down into it and the mains water comes up from it. At the bottom it just seems to be stones/dirt.

I can also see what I believe to be the damp proof membrane, at the front corners of the hole. This worries me as it's been broken.

How do I go about fixing this? Presumably the membrane needs to be repaired first? Then what? Cement? Or expanding foam? Or something else? :undecided

SailorSam

When you say the DPC has been broken, i can't see how they brake, they're between 2 bricks. Do you mean it's been bridged ......... Has it been plastered over ?
I think i'd start by just cleaning it all out and trying to dry it out. Use something like a hairdryer. Then you can start to look for any problems.
If there are any joints down that hole that you think you may need to get to in the future sometime, i wouldn't fill the hole with concrete, if you wanted to make it look cleaner you could just fill it with sand or small chippings (but don't bridge the DPC).
If the damp course has gone i don't think it's an expensive job. If you're handy i suppose you could do it yourself but even getting a man in they probably just inject the walls.
Look on the outside as well, to see if any sign of 'bridging' there.

firsttimebuyer2013

SailorSam wrote: »

When you say the DPC has been broken, i can't see how they brake, they're between 2 bricks. Do you mean it's been bridged ......... Has it been plastered over ?
I think i'd start by just cleaning it all out and trying to dry it out. Use something like a hairdryer. Then you can start to look for any problems.
If there are any joints down that hole that you think you may need to get to in the future sometime, i wouldn't fill the hole with concrete, if you wanted to make it look cleaner you could just fill it with sand or small chippings (but don't bridge the DPC).
If the damp course has gone i don't think it's an expensive job. If you're handy i suppose you could do it yourself but even getting a man in they probably just inject the walls.
Look on the outside as well, to see if any sign of 'bridging' there.

Well when I say broken, I mean in the way it doesn't cover the hole. Can you see the two edges at the front of the hole? I presumed it should be a continuous sheet over where the hole is?

Sorry, I don't understand what you mean about has it been bridged?

I've had a little portable heater on it. Will do so again tomorrow. Might take a while. lol

anotherbaldrick

OP means the DPC membrane on the concrete slab under the screed.
I would fill the hole up to DPC level with sand ,lay a bit of plastic on top and then fill with sand and cement up to floor level. Oh and make a waterproof job of the waste pipe

maninthestreet

Could that be a sink hole?

Bennifred

maninthestreet wrote: »

Could that be a sink hole?

aaargh!! :rotfl:

27col

If it was mine I would chuck a bag of gravel down the hole and maybe a thin layer of mortar over the top. That way, if it has to come up in the future, it is very easy to do.

firsttimebuyer2013

anotherbaldrick wrote: »

OP means the DPC membrane on the concrete slab under the screed.
I would fill the hole up to DPC level with sand ,lay a bit of plastic on top and then fill with sand and cement up to floor level. Oh and make a waterproof job of the waste pipe

I won't be able to go to floor level though because the soil pipe connection is lower than this. :undecided

firsttimebuyer2013

I think what I'm going to do is put a slightly wider pipe around the waste pipe, chisel away some more of the concrete hopefully exposing the damp proof membrane. Fill the void below this with cement, fixing the pipe in place, attaching new DPM to the existing and around the new pipe, then cementing over.

But all this after moving the stopcock higher so it's accesible through the back of the cupboard rather than under it.

Does this sound right?