black mould on wall behind wardrobe, advice please

Hi common problem here but I was just wondering if someone can give me a little info on a black mould problem my daughter has on her wall.

She lives in a modern purpose built 1 bed flat and had a free standing pine wardrobe in front of the wall that backs onto the communal hallway, when she pulled it away after about 18 months or so she found this (see picture)

Now I have some knowledge about moisture in properties from my past but it is not comprehensive. I know that you get moisture on glass windows when they are cold and the warm air condenses on them and I think they said to open windows to reduce the humidity in the room when this happens so is this what has happened to this wall?

The wall backs on to the communal hallway which is inside the block but obviously outside the flat so colder in the hall I would guess.

So my questions are why did this happen, could it be rubble in a cavity wall at the bottom or will this not be a cavity wall being internal?

Is the fact there is furniture there a contributing factor ie does it stop the heat or air getting there properly, surely heat and air can still get to the wall?

Is there any kind of problem here that needs to be dealt with or is just heat and ventilation required?

What could you do to prevent it happening again?

Any help or advice appreciated.

Easiest solution likely to be : stick insulation-backed plasterboard onto the wall using dot-and-dab.

This will raise the temperature of the wall and may prevent condensation. Not possible to say that it will as that depends on the mixture of how warm/moist it is in the flat and how cold outside.

That doesn't look like a lot after 18 months, so maybe as little as 20 mm insulation ( + 12 mm platerboard ) might be enough.

As per mointainwalker.

However it's a little odd to be getting mould in such an area, if you are not getting it elsewhere (I assume as you don't mention it).

To get cold bridging from a unheated hallway, but not on external walls is a bit odd, make sure there is no source of damp, leaky pipes, missing DPC etc. Or check if they did actually insulate that wall?

happyhero said:

So my questions are why did this happen, could it be rubble in a cavity wall at the bottom or will this not be a cavity wall being internal?

Is the fact there is furniture there a contributing factor ie does it stop the heat or air getting there properly, surely heat and air can still get to the wall?

Click to expand...

Basically, everyone produces moisture in the property. This will either linger in the air, or condense on something cold. Normally it would be most vissible on window glass, but it also condenses on walls floors and ceilings.

Once condensed, it will either evaporate away again (to continue the cycle) or will remain for longer periods. If the condensate remains, it provides a good environment for mould to grow and spore

It only takes a minute change of temperature or slight lack of air flow to upset the equilibrium to allow a particular part of the property to experience condensation and then mould

What is most likely happening at the flat is lack of air flow, behind the furniture, but even so there may also be a more general issue with excess moisture in the property as a whole.

Read up on the many condensation posts or info on the net. But is is not as simple as ventilating and heating more. Its a very fine balance

If I were to bet you 50p that she is in the habit of draping wet washing around the flat, and over radiators, would I win?

Had a similar problem years ago and ended up buying a roll of polystyrene about 3mm thick the type you put under wallpaper (not sure if you can still buy it) pasted it to the wall and no more problems.

The answer will be from one of the three following words:

1. Ventilation.
2. Ventilation.
3. Ventilation.

Andy

common problem on these new build flats with communal hallways.

mostly becasue the hallways arent heated and they dont put any insulation in the walls between the two, why would you, its an internal wall.

so you end up with a very cold wall.

Ok thanks guys for so many replies I know I can thank you on your posts but you have been so good that I want to thank you properly here.

Oh and after speaking to my daughter with reference to your replies, yes she does often dry washing in the flat (although often by the back door with it open) in the other rooms but I suppose it is like a big box. She does ventilate but not enough and she has the bedroom cold as her boyfriend like it like that, so a bad combination with a cold wall to help.

Many thanks for all the help.