Looking for something to prevent mould growth on walls

Harry Angstrom

I've got a problem with a north-facing bedroom wall which never gets the sun. The wall tends to get very damp in winter and black mould spots appear. I've spent the past week cleaning the wall and I've got all of the mould off it but I need something to stop the mould from coming back. Can anybody recommend a brand of mould preventer that I can paint on the wall (which is readily available in most DIY stores)?

Also, would it be a good idea to give the wall an oil-based paint undercoat before putting emulsion on it? Would this be likely to stop the mould from showing through?

Thanks for your input.

DoneDL

You can get bathroom and kitchen paint which will be anti-fungal but in a bedroom you should consider is the room vented properly and is it hot enough. Are there any downpipes on that wall or is the gutter leaking.

DublinDilbert

Sounds like you've got condensation forming on a cold wall. No mater what you paint it with, it will be a sticking plaster. The wall needs some sort of insulation and the room needs better ventilation.

AckwelFoley

You dont need paint, you need better ventialtion

Harry Angstrom

DoneDL wrote: »

You can get bathroom and kitchen paint which will be anti-fungal but in a bedroom you should consider is the room vented properly and is it hot enough. Are there any downpipes on that wall or is the gutter leaking.

I'm living in a row of houses and everyone seems to have similar problems with dampness. I'm pretty certain that it's not a downpipe or gutter problem with me.

slimjimmc

Harry Angstrom wrote: »

I'm living in a row of houses and everyone seems to have similar problems with dampness. I'm pretty certain that it's not a downpipe or gutter problem with me.

Which probably just means that all the houses are the same construction complete with poor ventilation. Rooms should have a 100mm dia wall/window permanent vent, and leave it open. You can speed up the drying-out process by using a de-humidifier, you'll be amazed at how much water those things can pull out of the air.

DanWall

I had a house which was an old cottage dry lined attached to a new cavity insulated construction. I got black mold in the new section. Although there was no sign of any damp anywhere, I recond that there was moisture in the air from the old section condensing on the walls in the new section. Note that this mold is toxic with spores in the air that can cause health problems

AckwelFoley

DanWall wrote: »

I had a house which was an old cottage dry lined attached to a new cavity insulated construction. I got black mold in the new section. Although there was no sign of any damp anywhere, I recond that there was moisture in the air from the old section condensing on the walls in the new section. Note that this mold is toxic with spores in the air that can cause health problems

Lack of ventilation is the problem here too.

Harry Angstrom

AckwelFoley wrote: »

Lack of ventilation is the problem here too.

So if I keep the windows open as often as I can, and I keep wardrobes, drawers etc. well away from the wall, do you think it might fix the problem?

DanWall

AckwelFoley wrote: »

Lack of ventilation is the problem here too.

That's a good point, but the house I am in now has no sign off mold even if I shut all vents, it is well insulated though.

CBYR1983

Zinnser paint.

sohappy

got some of this in the paint shop,only just used is so cant say if it works or not, €13 for a bottle that does 10L of paint
http://www.floodaustralia.net/products/anti_mould/VC175.php

Hmmzis

I'd second the insulation approach. Mold forms in wet/damp places with stale air.

Dampness is usually cured by insulating the outer walls of a building or room. Even a properly fitted foil type insulation will prevent condensation from forming. If you can fit insulated plasterboard or rigid foam with foil on both sides, even better.
Make sure you also apply some insulation around the window isle, too (most people seem to miss this for some reason).

The other thing to check is the DPC layer of your house. Has it been bridged by something? Like added top soil, concrete slabs, raised flower beds or any other stuff that might soak up moisture from the ground and release it into the wall. Is the DPC even there? If not, then that will cause a lot of problems with dampness. There are options of chemical ones, but they don't come cheap .

Anti mold paint can keep the mold at bay but a room that's damp won't be very comfortable to be in and it won't exclude the mold appearing in other places.

And last but not least - ventilate the room. If there are no vents in the room, then open the window at least once a day to get the air moving (for half an hour or more).

Harry Angstrom

Thanks for that Hmmzis. This might sound silly but do you think it might make any difference if I pasted a couple of layers of tin foil to the wall before papering over it and then painting? Do you think it might improve its insulation a small bit? I can't really afford to do much else with it at the moment.

BryanF

Harry Angstrom wrote: »

Thanks for that Hmmzis. This might sound silly but do you think it might make any difference if I pasted a couple of layers of tin foil to the wall before papering over it and then painting? Do you think it might improve its insulation a small bit? I can't really afford to do much else with it at the moment.

I afraid this sounds silly, boarding on the ridiculous

you've aready been told what to do. add insulation preferably externally and ventilate properly with fixed 'open' wall or window vents.

MrThrifty

Key simple fix as people have said is to improve ventilation. People live in bedrooms for ~8 hours a day and therefore expel a lot of water vapour through their breathing. Also since the room's northfacing, it's not going to be a particularly warm room to begin with and therefore I would guess that any vent there has been closed which then leads to the water vapour getting trapped in the room. Simple proof of this is water collecting on the insides of windows in the morning. Open vents (or door of room at night time) and make sure room is properly heated - it's all too easy to sleep in a very cold room while snuggled up in the blankets!

DanWall

You have to consider where the moisture is coming from, have you an extractor fan over the cooker and in the shower or bathroom? do you dry clothes in the house? Have you got a gas cooker? the act of combustion generates water,

AMG86

Lack of ventilation is the main problem See attached
http://www.proair.ie/index.php?option=com_content&task=view&id=63&Itemid=209. Installation of a MHRV system would help solve the problem if done in conjunction with insulating the house. It would also result in lower heating costs on an ongoing basis