Condensation Mould or Damp

KTJ_2 · 25 February 2008 at 12:38PM

Hi all,

We have black mould patches appearing in the top and bottom corner of our bedroom. We do not have trickle vents and sometimes dry clothes in the bedroom. My immediate thought is that its condensation.

I have had a few builders around and have had mixed advice. One said the rendering on the outside needed re doing as the rain was getting in, another said the valley in the roof was letting in water and and another. I have rang a damp specialist and they wouldnt send anyone out after i had said the mould was black as they werre convinced it was condensation and not damp.

So......my question is...Whos advice do i take. Is there any clear way of knowing whether its a leak or damp problem or just condensation? I'm loathe to redecorate, get a dehumidifier, install trickle vents if it is a leak and conversly, I dont want to spend thousands on roofing/rendering if its just condensation.

Any advice?

Greenr · 25 February 2008 at 2:02PM

We had the same problem. Try this:

1) buy Dettox Mould and Mildew spray (lime green spray bottle) and wipe off any existing black mould
2) open windows as often as possible (even if it's just for an hour in the morning)
3)make sure windows are open if you're drying clothes (and use a dehumidifyer when drying if you have one)

We did the above and the problem has gone!!!

If you're problem doesn't go, then it can't be condensation damp...

bikertim · 25 February 2008 at 11:54PM

If the mould is in an arc in the corners it is condensation.Also if you have damp 9 times out of 10 there is a white fluffy substance which is the salts coming out.From what you have said I would say it is condensation.It will need to be washed with a fungicide and mould killer.Then ventilate and heat the room.Do not dry clothes in there without ventilation.

Poppycat · 26 February 2008 at 12:00AM

It could be several things, rain getting in through rendering or porous brick, leaking drainpipe (assuming its a outside wall that is having the problems. Or it could be condensation or lack of air flow

I wouldn't use the dettox spray its powerful stuff and if you get it on carpet it could bleach. I rather use bleach strong dose and protect carpet and when a dryish day open windows just wipe with a loth with bleach but make just its just damp clothe not soaking wet. The dettox spray can go a wide area and it isnt very good for breathing in.

Also invest in a dehumidifier. Drying clothes in a room only causes problems unless you have adequate heating, and or dehumidifier to take up the water in the air. Getting a dehumidifier is a good investment for our homes which often suffer from lack of air flow due to double glazing etc

The warmer a room is the more it can absorb water, when room cools the water vapors condense on a cold suffice, hence the outside walls and windows often get wet

jimbo_the_jetset · 26 February 2008 at 11:56AM

You can hire a dehumidifier from most hire shops. Try before you buy and see whats what (it is amazing how much water they suck up!!)

KTJ_2 · 26 February 2008 at 2:47PM

Thanks for the advice all

barjam_2 · 26 February 2008 at 3:24PM

someone correct me if i'm wrong we recently had tiles on i roof repaired as there was loose ones hubby mentioned we have black on our bedroom ceilings the 1st thing the guy asked was "do you have anything in your loft which are in plastic bags"? our answer was yes... he said everything should be in boxes and nothing in plastic bags its that what's causing the damp,

as i say corect me if i'm wrong i'm only going off what we were told, and i would also like to know if it is actually true

fumken · 22 April 2008 at 9:54PM

I have a serious case of black marks and mould on my external walls. I recently installed double glazing and noticed the walls were "sweating". Now all the external walls especially the corners have black marks. When I peeled some of the wall paper, I observed that even areas that dont show yet already have black mould. Please what can I do? Will a typical building insurance cover this? I put a new bathroom shortly before the d/glazing and it turned out that the so called builder was a quack and there was a leakage from as well as a very poorly finished job - which actually resulted in my ceiling caving in. I paid 2000 pounds for thebathroom job and I was ripped off basically and I have not even found away round that, so I am rather worried about this new development. I dont even know where to start.
1. What are the likely causes and remedies?
Can I also do anything about the bathroom rip-off, especially if found to be the cause of this. I did not want to act on that before, as he is married to someone I know, but this is serious.

TimBuckTeeth · 22 April 2008 at 10:31PM

fumken wrote: »

I have a serious case of black marks and mould on my external walls. I recently installed double glazing and noticed the walls were "sweating".

That is condensation. Before the double glazing the humid air would condense on the windows as they were the coldest thing in the room, removing the moisture from the air. Now the coldest thing is the external walls so the condensation forms on them.

You need to increase the ventilation in the rooms by opening the windows as often as possible.
Maybe get a dehumidifier to remove the moisture from the leak. Does the new bathroom have an effective extractor fan as showers increase the humidity a lot.

In the long term you could consider cavity wall insulation, it should keep the internal walls warmer and less likely for condensation to form.

fumken · 23 April 2008 at 9:10PM

Thanks very much. I had cavity wall installation done about 8 years ago. Is it possible to do it again? Its a 1930s end of terrace house. I will also contact the D/G company about putting in vents. The bathroom has an extractor.

phill99 · 23 April 2008 at 11:40PM

As sure as God made little apples, black spore on internal wqalls is condensation caused by:
1. High levels of humidity in the atmosphere caused by bathing, cooking etc.
2. Lack of appropriate ventilation
3. Differential temperatures on the inside and outside of a surface.

It is imperative therefore to do a number of things:
a. When you cook using saucepans etc (pasta, rice, veg, potatoes etc) that you put a lid on the pans, keep the kitchen door closed to avoid the moisture moving all around the house (warm moist air will always be attracted to cold dry air). Either open a window to allow steam out or ideally, use mechanical ventilation (remembering to keep it on for a while after yoy7 have finished cooking)
b. When showering or bathing, keep the door closed, even afetr you have finished, open the window, or ideally, use mechanical extraction. The extractor fans that come on when the light comes on have a major flaw - if you shower/bath during the day, they don't come on. You ideally need one that works independent of the lights and you need to get in the habit of using it. Again operate for a good 20 mins after you have finished showering and keep the door closed
c. The room where you have black spore needs ventilation (trickle vents on the top of DG windows are inadequate therefore open the window) AND needs background heating in order to make sure that there is not a significant differential between the inside and outside temperatutes (ie the wall will be warmer and therefore the air borne moisture will not condense on it.
d. Additionally, insulate where poss both in the roof space and the walls (cavity wall insulation) as again this will minimise the temperature differential.

Basically, you have black spore because there is insufficient ventilation in the houise and there is too much moisture in the atmosphere, both of which are down to the occupiers!

Condensation Mould or Damp

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