1940's Kitchen internal floor level below DPC

[Louweazle]

Hello could anyone give me some advice about my kitchen/downstairs loo floor?

Our house was built in 1946 and is the kind of semi that has a single story extension at the side. We think that originally this may have been a coal store, downstairs loo and possibly a scullery/kitchen. At some point it has been knocked through into one larger space with a little lobby to keep the new kitchen and loo separate. It doesn't appear to have cavity walls - going on the depth of the window sills, and we are not sure whether it has been dry-lined.

Ok here's the problem...
The floor in the loo is very wet where it joins the outside back wall and not quite so bad along the outside side wall. The skirting is wet and begining to rot. There don't appear to be any leaks from the loo itself, though we found a problem with a broken drain about two feet from the sidewall - must have been leaking for ages but now sorted. The internal floor of the loo and kitchen is below the level of the dpc, and we think this may be part of the problem. We appreciate that there may be a large moisture resevoir at the base of the side wall from the old leak, but most of the wet is at the back wall/floor.
Is there any way to combat this without raising the floor level?
Would French drains help? The oustside ground level is pretty much the same as the internal floor and we intend to lower this at the same time as digging the French drains. Would tanking the floor and walls up to the DPC help?
If we must raise the floor what's the best way to go about it?

Sorry to ramble on so much If you have stuck with me this far your patience is very much appreciated.
Thanks
Louise

 

[JohnD]

It sounds so wet that I think you have a water leak, not just a bit of damp.

does the incoming water main run in the floor?

Is there condensation e.g. on a cistern?

 

[Louweazle]

It sounds so wet that I think you have a water leak, not just a bit of damp.

does the incoming water main run in the floor? - We think so, it rises out of the floor up the inside wall - opposite side to the wettest patch. How would we check it out?

Is there condensation e.g. on a cistern?

We do have condensation problems in the whole extension as it has a flat (we think concrete) roof. We know we will have to put in a new ceiling with more insulation but thought we should sort the loo floor out first.

I forgot to say the air brick in the loo had been blocked and we intend to reinstate it.

 

[JohnD]

It is very likely the old water pipe is leaking.

It is probably made of steel
One of the most likely places for a leak is the elbow where the pipe turns upward to emerge from the floor.

You can chip out the floor using a club hammer and chisel or bolster.

You will need gloves, goggles and ear defenders.

You can dig it out yourself to investigate. If the hole you chip out fills with clean water you can be confident this diagnosis is correct. If it fills with soapy water or smells of sewage or toilet cleaner then it will be the drain.

Jointing on steel pipe is not an amateur job. You need a plumber who is old enough to have experience and suitable tools. It is not the same as working in copper pipe as you have to thread the pipe and screw fittings onto them. Lead pipe is actually easier to work with than steel. If you are getting a pro in he will most likely have a suitable drill for breaking up the floor as well.

You are always best advised to ask around friends and neighbours for a recommended plumber.

If you can find the stop-cock you may be able to estimate the route the pipe takes under the floor. the leak might even be in the ground outside if the pipe comes in that way but it must be pretty close. a water leak that is not in concrete will tend to flow downwards as it washes the ground away and forms a cavity.

the old floor will not have a DPM so you can consider fitting one when you renew the floor. this will reduce damp and so condensation.

 

[Louweazle]

Thanks for the advice
I just pulled back the lino from where the main comes up from the floor and it's the only dry patch within three feet of the back wall/loo
I think we will check that out though.
I am thinking that whoever put the loo in (its not the original one) may have punctured the dpc membrane assuming there ever was one - I am beginning to think this a very dodgy conversion and that the original floor in there may have been bricks on soil. There is a good six inch step up into the rest of the house.

It is very likely the old water pipe is leaking.

It is probably made of steel
One of the most likely places for a leak is the elbow where the pipe turns upward to emerge from the floor.

You can chip out the floor using a club hammer and chisel or bolster.

You will need gloves, goggles and ear defenders.

You can dig it out yourself to investigate. If the hole you chip out fills with clean water you can be confident this diagnosis is correct.

Jointing on steel pipe is not an amateur job. You need a plumber who is old enough to have experience and suitable tools. It is not the same as working in copper pipe as you have to thread the pipe and screw fittings onto them. Lead pipe is actually easier to work with than steel. If you are getting a pro in he will most likely have a suitable drill for breaking up the floor as well.

You are always best advised to ask around friends and neighbours for a recommended plumber.