Black Mould

MouldyOldDough

We have black mould on the ceiling of our bedroom - it appears to be due to condensation rather than from the roof - it is up against the wall on the sloping part that I believe is non insulated and is directly below the tiles !

We use a mains dehumidifier and have done for years - but, for some reason, this year, we have mould

Is this purely down to ventilation or is it down to temperature in the house - it is rarely above 18  degrees in the bedroom and the main CH thermostat is set to turn the heating on at 14 degrees !

I read that mould thrives in warm damp conditions- but what does "warm" mean ?

What is the best way to remove the mould (which mould spray really works ?) and how  do we stop it returning ?

grumbler

Thick bleach and a brush - you have to do this periodically as, IMO, the mold is impossible to 'remove' permanently. And it doesn't need a 'warm' place to grow.

Post a photo and consider insulating this part of the ceiling - possibly, by adding insulated plasterboard.

MouldyOldDough

According to the display on

grumbler said:

Thick bleach and a brush - you have to do this periodically as, IMO, the mold is impossible to 'remove' permanently. And it doesn't need a 'warm' place to grow.

Post a photo and consider insulating this part of the ceiling - possibly, by adding insulated plasterboard.

I am unable to post photos as a newbie

SaverRate

Try painting the ceiling with anti-mould paint e.g. https://www.screwfix.com/p/dulux-easycare-bathroom-paint-pure-brilliant-white-2-5ltr/42729

Bigphil1474

We get it in our bathroom quite often, despite leaving the window open quite a lot. It's only at the end near the window, presumably because the ceiling there is cooler, more condensation forms, and therefore more mould grows.
I use thick bleach - dab it on. Cleans the ceiling up nicely and if I do it in the winter, it usually sees us through to the autumn. You could look at having that part of the ceiling better insulated, or just give it a good clean once a month.

aoleks

slightly off topic, but can I ask how people live with a temperature of between 14 and 18 degrees in a house? isn't the whole idea of a house that it's nice, warm and cosy and doesn't replicate the temperature outside on a chilly day?

I would literally shiver at those temperatures and I wear normal clothing inside in the winter (trousers, socks, t-shirt, long sleeve top).

MouldyOldDough

aoleks said:

slightly off topic, but can I ask how people live with a temperature of between 14 and 18 degrees in a house? isn't the whole idea of a house that it's nice, warm and cosy and doesn't replicate the temperature outside on a chilly day?

I would literally shiver at those temperatures and I wear normal clothing inside in the winter (trousers, socks, t-shirt, long sleeve top).

The wife feels the warmth
I feel the cold 
Wife wins! 

another_casualty

I get mold now and again in the bedroom . Mainly on window frames and on one of the external walls . Dehumidifier has been great , but now and again a flash floorwipe cleans it off ..

Phil4432

Mold apparently forms when there is condensation; which occurs at 14C.  However, it can still occur if there is a cold spot, like the inner wall of a bay window.

From what you've described, that's a cold spot on the ceiling which is why you are getting condensation.  You could get that part insulated somehow, or just clean the mold off regularly and apply some anti mold paint.  That may just mean cleaning the mold off less frequently. 

Bigphil1474

aoleks said:

slightly off topic, but can I ask how people live with a temperature of between 14 and 18 degrees in a house? isn't the whole idea of a house that it's nice, warm and cosy and doesn't replicate the temperature outside on a chilly day?

I would literally shiver at those temperatures and I wear normal clothing inside in the winter (trousers, socks, t-shirt, long sleeve top).

We only have the heating on for an hour in the evening - set at 19oC. In our house, you are either busy doing something so don't feel the cold, or you are tucked up on the sofa with a cosy blanket watching TV/reading etc. Fortunately the kitchen warms up from cooking tea so we can dine in a comfortable temperature. 

grumbler

Phil4432 said:

...condensation; which occurs at 14C.

Is it a fact?