humid weather

[Ambernewbie]

Hi all. Need a bit advice please. We are having terrible trouble with mold on 2 walls. They are both external walls that doesnt get any sun - ever. They are def not damp - we have had it checked out. they are very cold.
My question is should i open windows when it is damp/raining outside to get rid of the humidity. I would think no prsonally but I reading so many conflicting thoughts.
the mold seems to appear from nowhere and it is getting so hard to get on top of it.
Any advice please??

 

[pcaouolte]

It will be condensation. The warm humid air inside the house comes into contact with the cold surface of the wall and condenses making the surface of the wall wet. The mould needs this moisture to survive.

Opening windows for a while every day may help. try to get some air movement by opening windows on opposite sides of the house at the same time to let the air move through. You will need to experiment with the amount of time, start with 15 minutes per day.

If it is windy you may need less time. If it is pouring with rain choose a different time. Normally the air outside the house contains less moisture than the air inside. You are trying to change some of the warm moist air inside for colder dryer air from outside. It's a trial and error thing.

The biggest difference will be achieved by getting rid of the moisture at source. Use extractor fans in bathrooms and kitchens, cook with lids on pans, don't drying washing indoors.

 

[foxhole]

Mould does not come from nowhere, mould spores exist in homes but usually air movement prevents them settling and also removes the conditions they require (cool damp walls).So ventilation is essential .

 

[Mike13]

You need to look at and understand relative humidity and the change of water pressure with temperature.
at 0C air with 100% relative humidity has ~0.5% water in it.
at 20C air with 100% relative humidity has ~2.5% water in it.
Your job is to make sure that any air in the room does not have enough water held in it to get to 100% when it is at the temperature of the walls.
The best strategy will change with the seasons.