Problems with fungus on kitchen wall

Thanks Ben will have a look, willing to try anything.

Hi Margret,

I too had a problem with fungus in two places in my home. The one shower ceiling got dark fuzzy mould growing which we removed several times with bleach and water. We eventually replaced the extractor fan and now leave the small bathroom windows open all the time. It has not been back for a few years but the bathroom is a little chilly in winter. It gets little sun and is narrow so ventilation is clearly a problem.
The other fungus appeared on the wall of a passage outside the bathroom. It was white in colour and very fuzzy. This appeared after about 4 years of a slightly white patch on the cretestone that would come and go. When the mould was wiped off a slight damp patch could be seen. We knew it wasn't the shower floor but suspected a pipe in the wall about a meter up. One of the joints was leaking ever so slightly.
I hope you find the source....

We had a problem with mould living halfway up a mountain in Hong Kong, very often in the clouds. One day when we got up the walls had turned black overnight with mould. My husband mixed some packets of athlete's foot powder in a bucket of water - scrubbed the walls and that was the end of the problem.

I can't fault Ben's advice, mainly because, as my wife will attest to, I know little about biology, but it sounds good.

Well, it's good news then, because a 60s built house should work properly and have a cavity wall.

Now we're onto something manageable.

Your mould is either a result of poor ventilation of external water ingress.

You say that your roof is fine, but at 50 years old, the membranes may well be breaking down. How confident are you about the roof advice?

More questions:

1. Are there any existing vents in the house? If so are they working/unobstructed/furniture placed against them etc?

2. Have you changed/improved the doors and windows? If your house doesn't use designated vents to allow air to enter and leave your house, then the air enters and leaves by doors and windows, or rather the gaps around/under them. Modern doors and windows will hugely improve air-tightness. Do you have trickle vents in new doors and windows?

3. Has anything changed externally? Footpaths/retaining walls/planters/trellis etc?

4. Are all of your external levels lower (ideally 150mm) than the internal floor?

5. Are your gutters clean and working? An overflowing gutter will happily soak the top of a wall.

6. Can you clarify where the mould is, height etc.

For clarity, if your dehumidifier is filling it's container on rainy days, it tells you one thing - there's more moisture in the air in your house on rainy days. It's not a good guide to where your mould problem is!

So, we've got to identify if the water is coming in from the roof/gutters/walls or whether it's a ventilation issue.

Again, it's a 60s house so it's entirely fixable: Stop rain or condensation coming in and get the air changes right.

Your 5000 Euros is safe.

Hi Margret:

once established on (and more-over in) a wall they're hard to get rid off. Their spores may have been present for years already and waited only for the right combination of temperature and moisture to become active. You don't need excessive moist conditions to have fungus growing, some of the species are very happy with the normal, 50-60% humidity in the air. But you really need to eradicate them, bleach helps to kill of the visible part of the fungus, but leaves a number of spores intact. Once the chlorine of the bleach has evaporated in the air the spores will start to grow.

My simple but best advice would be to go to a DIY-shop and by a can of paint, specially designed to cover fungus traces, which contains also an active exterminating agent.

It is very kind of you Henry to take the time and trouble to try to help with this problem, sorry I didnt reply sooner.

Please dont worry about your carte vitale it took me 2.5 years to get mine and that was going to the RSI office in Agen and after visiting it took another 4 months before I received it. I did have to get my birth certificate translated to french. Youre attestation with your insurance no. etc. is sufficient at the moment to get health care cover.

Here is the answers to your questions:

1. Ther was nothing changed or added on to the house last year it did not get any better from the July onwards when it started and although we cleaned with bleach and cold water then painted that part of the wall with anti humidity paint it is coming through again.

2. The house was built in 1960 and we believe brick block construction.

3. The walls in the kitchen have no plasterboard on them it was crepied straight onto what looked like concrete. We do have an air purifier/dehumidifier but each day there is vry little water in the container.

It is raining today and if there is a lot of water in the container I think that would tell us its coming from outside.

If yçou have anything else you can suggest to try find out the problem I would be most grateful.

Oh Margaret,

I wish sorting a Carte Vitale was as easy as this issue, at least there are a finite number of possibilities!

It makes my blood boil when I hear posts like this: “I’ve got some moisture in my house and now it’s going to cost 5000Euros to install a machine in the loft” AAArrrggh! Where do some people get off?

OK, more helpfully, in order to track down the source of this problem (and that’s what we need to ascertain, rather than treat the symptoms) we need more info:

  1. You say that the fungus appeared last summer? Can you clarify if anything changed then and if the problem gets better or worse in winter? Did it go away in summer when you had doors and windows open (I assume)?

  2. How old is the house?

  3. What is the current wall construction?

  4. What work was done to the house?

Condensation will form at the dew point, the smoother and flatter this surface the more attractive it’ll be for condensation (window glass for example) adding an internal layer of plasterboard to a wall that doesn’t have a ventilated cavity, or other suitable method of vapour control, is highly likely to move the dew point to the plasterboard face.

So we’ve got:

  1. Dew Point of walls are at the internal plasterboard face.

  2. External walls are getting wet from external rain, gutter problems or roof water penetration.

  3. It’s forming from kettles, pans etc.

So, if you’ve got external water problems, you need to ascertain the problems and fix them.

Wandering around with a pronged hygrometer will tell you what? that your wall is a % moisture content for the first 10mm max?

Never be duped into taking the advice of a £30 moisture meter carrying expert who wants to sell you something.

If you can move/exchange the air then that’s going to help. You can simply install a kitchen extract fan (not 5000 Euros) or install a combined extract system (you’ll get a reasonable kit from Brico for a 100 Euros) installation of this kit is subject to the builderswork required of your house, but there’s quite alot of work left in 4900 Euros.

Worst case scenario, you’ve got a wall that doesn’t manage the moisture, perhaps a stone wall with plasterboard lining? In which case, you’ll need a bespoke solution, but if your plasterboard is soggy, you’re looking at removal anyway.

Don’t suppose you know if the plasterboard was hydrofuge (green coloured) when installed.

Hi Nick

Thanks for that. Will try googling it. Couldn't find a humidity meter in our local brico.

Hi Margaret, sorry I didn't get back to you earlier.

There are a lot of specialist companies around. Try putting "Traitement humidité des murs" into google and that should throw a few companies back to you.

Good luck

Ok will go to our brico to try to find one. If it is in fact inside the wall who would I call to fix the problem, I know this sounds stupid but just dont know where to turn to try to sort this out.

Again many thanks.

The consensus from my French colleagues here is a "Sondeur d'humidité"

Thanks Nick yes we have done what you said and also bought an air dehumidifier, maybe not using it long enough!

I have noticed today after writing this post there are 4 more spores at the other end of the wall and the bedroom above has a small dark area on the ceiling which was newly plaster boarded and skimmed, this is what makes me think it is water inside the wall but the expert said he tested the wall and there was none. I am still doubtful because I felt he just wanted to sell us the machine.

Have you any idea what the name for a damp meter is in french?

I don't think you need to be spending that amount of money.

Have you tried making sure your kitchen is properly ventilated, windows open and closed for example, that kind of thing.

If it is properly ventilated and has a good air changeover, then it is probably likely to be more some kind of residual damp. That could come from anything from a kettle or a toaster to even the heating system. As warm air condenses on a colder surface it can quite easily form damp. This is usually eradicated when there is proper ventilation.

Otherwise the damp could possibly be in the wall itself and for that, you will need to test with a meter. You should be able to pick up a damp meter fairly cheaply at a good DIY store.