Damp / Mould Behind Washing Machine and Dishwasher

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Hi all,

So we have recently noticed a damp patch on our external brick work. It isn’t due to rain, as other mortar and bricks are dry.

This damp is directly outside our washing machine and dishwasher in our kitchen.

As I am writing this, there is also some damp on the external brick work where the pots and pans cupboard is. Smells musty in there, too.

Anyway, have removed the two machines, and there it is – a mass of black mould.

I can’t see any signs of either the washing machine or dishwasher leaking. We have never had water come through to the “living area” of the kitchen. That said, that isn’t to say there couldn’t be a minor leak which has been unseen for years?

Our bungalow is a 1955 build. It has a concrete floor. Don’t think it has a damp proof membrane. It does have a damp course membrane, though.

Rising damp? I don’t think so. It feels too coincidental to be behind these machines. And, everywhere else below the damp course membrane is dry.

Damp course failed? I don’t think so. While the brick and mortar below the damp course are wet, it is not nearly as wet at the brick and mortar above. See photos internally and externally.

Mains water supply leak? I don’t think so. We have 15mm pipe up through the screened floor. Have push the cold tap on full blast. Can’t see any signs of leakage.

Damp due to cold? Could be? But, we do have cavity wall insulation. In fact, one of the “pockets” is about one metre directly above the damp, so no doubt this damp area has insulation too.

Looking externally, about 1 metre right of the damp, we have an air brick. Totally dry around that area. See photo.

EDIT: Running along our mains water supply, we have wiring that runs to a socket and two downlights. Not sure if it is my imagination, but seems whenever I have the tap on, one of the lights flicker (half that little LEDs are already dead). Never had an issue with the other light or double socket.

EDIT: From the wiring to the mains water supply, is an earth connection. Recently, our washing machine has tripped, and blown two fuses. Surely the two are correlated?

It might be worth noting that we don’t have a radiator in our kitchen. We do have an electric heater, but rarely use it. However, it is a small kitchen. This shouldn’t be a problem, should it?

Any ideas?

Thanks in advance.

Doozergirl

I can't see a photo of the damp on the wall outside, but inside to me looks more like condensation than a leak.  

Maybe moist air escaping from the tumble dryer and settling on a cold patch of wall that either isn't insulated or has some kind of thermal break like rubble in the cavity.  Retrofitted cavity wall insulation isn't hugely reliable.   Given that there is a window above, rubble could be a contender? 

The mould also looks more concentrated on the side of the dryer.  

FreeBear

laurencewhymark said: Mains water supply leak? I don’t think so. We have 15mm pipe up through the screened floor. Have push the cold tap on full blast. Can’t see any signs of leakage.

Copper pipe running through a cement screed ?

Cement will corrode copper over time unless the pipe is sheathed in plastic. A pressure test of the pipe might show that it is leaking. It only needs to be a pinhole for damp to form.

It could be debris in the cavity, but you'd need to either remove a brick or drill a hole to insert an endoscope.

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FreeBear said:

laurencewhymark said: Mains water supply leak? I don’t think so. We have 15mm pipe up through the screened floor. Have push the cold tap on full blast. Can’t see any signs of leakage.

Copper pipe running through a cement screed ?

Cement will corrode copper over time unless the pipe is sheathed in plastic. A pressure test of the pipe might show that it is leaking. It only needs to be a pinhole for damp to form.

It could be debris in the cavity, but you'd need to either remove a brick or drill a hole to insert an endoscope.

My thought too. 

But, I don’t know if it is sleeved or not. T’was like that when we got here. Or, whether sand was used around it. Think that was the practice “back in the day”?

However, the little copper elbow coming out of the ground does have some green oxidisation on it. Though, not sure if this is necessarily corrosion, is it?

However, if that were the case, then surely the brickwork and mortar below the damp course membrane would be wetter than the brickwork and mortar above it?

FrankRizzo

Hi, is there any damp directly behind the tire brick - prob no? If thats the case then as you say its unlikely the machines are leaking so more likely to be a problem with your cavity insulation  - I am no expert but have heard if not done correctly can result in damp. Did you get a guarantee and is the company still in business?

FrankRizzo

*vent brick

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FrankRizzo said:

Hi, is there any damp directly behind the tire brick - prob no? If thats the case then as you say its unlikely the machines are leaking so more likely to be a problem with your cavity insulation  - I am no expert but have heard if not done correctly can result in damp. Did you get a guarantee and is the company still in business?

I can’t see any damp behind the vent brick, no. But, can’t really access that area internally. Externally, around it is dry.

I too have heard horror stories of cavity wall insulation… but we have it all over the house… and never any issues elsewhere (that we are aware of).

The insulation was done prior to us moving here. We have only been here a year! Our first home.

FreeBear

laurencewhymark said: However, the little copper elbow coming out of the ground does have some green oxidisation on it. Though, not sure if this is necessarily corrosion, is it?

The green will be a copper salt. Either caused by excess flux that wasn't cleaned off properly, or a reaction with some other contaminant. Without a close examination, it would be difficult to say for certain the corrosion was being caused by the cement.

Le_Kirk

Have you a water meter fitted?  If so, have a look at it with, say the kitchen cold tap turned on and you can see it turning; then make sure everything requiring water flow is off such as kitchen cold tap and any toilet cisterns, cold water storage tank etc.  Does your water meter turn?  If it doesn't - no leak!

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FreeBear said:

laurencewhymark said: However, the little copper elbow coming out of the ground does have some green oxidisation on it. Though, not sure if this is necessarily corrosion, is it?

The green will be a copper salt. Either caused by excess flux that wasn't cleaned off properly, or a reaction with some other contaminant. Without a close examination, it would be difficult to say for certain the corrosion was being caused by the cement.

Hmm, interesting. As, our dishwasher uses “salts” for cleaning the machine itself. And I had noticed a fair bit of it had leaked through the bottom of the machine (through a poorly sealed vent, I think). Would need to flip the machine on its side for a closer look.

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Le_Kirk said:

Have you a water meter fitted?  If so, have a look at it with, say the kitchen cold tap turned on and you can see it turning; then make sure everything requiring water flow is off such as kitchen cold tap and any toilet cisterns, cold water storage tank etc.  Does your water meter turn?  If it doesn't - no leak!

Good idea!