Cavernous hole revealed under toilet!

[edb1984]

Evening all

i am starting a wet-room conversion on the ground floor of my house.

today i removed the toilet (With much difficulty) as it was cemented onto the concrete foundations!

while chipping away at the mound left once the toilet was removed the floor underneath gave way and reveled a 30cm deep hole roughly 60cm in circumference.

poking around i found that the waste pipe (the old Clay ones) that went into the ground then out under the wall to the manhole outside was loose at the 90' bend and put it down to the fact it must have been ****ing out water underground each time the toilet was flushed, and due to the water buildup it has damaged the foundation underneath, creating a small sinkhole.

Poking around and smashing up the top layer i cant see that this issue is anywhere else in the bathroom, although i am due to start chiseling out the floor to accept a wet tray former tomorrow so i may find more!

i am planning to fill the ground back in with some hard-core i have left from another project and plan to cement over tomorrow with some of that stupidly expensive fast setting concrete.

do you guys agree that this is more than likely the source of this issue? - or is there something bigger i should be looking out for?

 

[Jackrae]

Almost 50 years ago I had a similar problem with an old solid floor house I'd bought. I suspected the toilet was leaking 'somewhere' so I dug down outside the house to expose the sewer, cut the sewer out where is passed through the wall, then watched in amazement for several days as 'fluid' drain from the house underfloor. If you know there has been washout around the foundations then, after allowing the subfloor to adequately drain (it may take several days) it's concrete, not rubble you need. There's no "next day" fix.

 

[Hugh Jaleak]

Chances are that the majority of the old clay drain could be knackered, I'd be looking to replace that to at least a point outside the building, before making good any of the floor.

What are the damp proof arrangements for the floor?

 

[edb1984]

Chances are that the majority of the old clay drain could be knackered, I'd be looking to replace that to at least a point outside the building, before making good any of the floor.

What are the damp proof arrangements for the floor?

It's got plastic sheeting under the concrete, and obove a layer of sand, .

The clay pipe is no longer going to be used so I am sealing it up.

Do you have a theory that the damp proofing is to blame?

 

[Aquaheat]

Evening all

i am starting a wet-room conversion on the ground floor of my house.

today i removed the toilet (With much difficulty) as it was cemented onto the concrete foundations!

while chipping away at the mound left once the toilet was removed the floor underneath gave way and reveled a 30cm deep hole roughly 60cm in circumference.

poking around i found that the waste pipe (the old Clay ones) that went into the ground then out under the wall to the manhole outside was loose at the 90' bend and put it down to the fact it must have been ****ing out water underground each time the toilet was flushed, and due to the water buildup it has damaged the foundation underneath, creating a small sinkhole.

Poking around and smashing up the top layer i cant see that this issue is anywhere else in the bathroom, although i am due to start chiseling out the floor to accept a wet tray former tomorrow so i may find more!

i am planning to fill the ground back in with some hard-core i have left from another project and plan to cement over tomorrow with some of that stupidly expensive fast setting concrete.

do you guys agree that this is more than likely the source of this issue? - or is there something bigger i should be looking out for?

Start obvious, and I'll tell you why in a minute. What's the are you live in called? What's the road name? What was there before your house?

Reason I ask is that I bought a house a few years back and had exactly what you are describing. It was in chelmsly wood and the groud below did and still is infested with rodents.

Ground floor toilet was refurbished and I found the same massive hole around everything.

I ripped all the suite out, laid bait and sat with a rifle. An hour and a half later I had 11 of the buggers! Set rat traps after that and caught 7 more in a week.

Went quiet after that so poured concrete into it and cured it for the time I was there. They will come up anywhere though.

Check for signs of them. Claw marks, teeth marks, droppings. Is the ground falling away or neatly dug? The residue goes somewhere!

I recommend a bit of bacon and a 22 with hollow points.

Jon

 

[Hugh Jaleak]

It's got plastic sheeting under the concrete, and obove a layer of sand, .

The clay pipe is no longer going to be used so I am sealing it up.

Do you have a theory that the damp proofing is to blame?

No, but you didn't mention any damp proofing arrangements and wanted to check you were putting something in!

If the clay pipe is no longer need, I would remove as much as you can, back to the manhole if possible and seal the connection off with concrete to rat proff it.