Remove mould marks from the wall and tenant rights

You need to consider why the mould is there - is it due to the house or lifestyle? You need to make sure you open windows each day etc to let air flow in. I know sometimes it can be due to the house itself though. Its worth getting a dehumidifer to reduce the moisture in the air, especially if you dry clothes in the house.

I highly recommend this paint (decoratingwarehouse.co.uk/zin…att) - fantastic stuff - I am slowly painting most of the house with it lol. I did the bedroom just before the first lockdown, and it still looks like new. Easy to clean of any marks too (a godsend in the kitchen!). I know its more expensive than some paint, but i find it worth every penny. Its also self priming and doesnt require an undercoat etc.

I've used Astonish Mould and Mildew Remover it's £1.20'ish a bottle. It's a bathroom cleaner by design but it's a mould killing bleach (just like other more expensive mould treatments).

I had a pretty extensive mould patch on my bathroom ceiling that I treated with a Polycel Mould Killer Spray product that didn't really work. Then I used this, which I use in the shower and is very effective at removing any mould in there. Used two liberal applications and it got rid of it all, I did two to be sure as the mould was spreading across the walls and just wanted it gone. You'd probably get away with using it once, you'll probably use 10% of the bottle at most.

When you apply it just spray on and leave it to dry for a day, DO NOT RUB OR DAB once applied even if it's dripping down the wall (just be careful to not let it drip over skirting board and onto carpet if you have any). It will leave a dark patch when you spray it on the wall and it might look like it will leave a residue but it won't, provided you don't touch it and just leave to dry it won't even affect the paint as it's white.

It is bleach so when using it wear gloves as it will affect your skin if you get it on your bare hands, its nothing major you'll just have dry hands and an odd sensation like it won't wash off when you clean your hands.

Finally you will have a residual bleach smell like after deep cleaning a bathroom for a few days.

Any cheap masonry paint will stop mould growth far better than anti mould paint. If the wall is white and can get cheap white masonry paint then will be good as gold. Masonry paint has strong anti fungicide and herbicide in (any name brand that is)

Sugar Soap also good for removing mould. Do it on day you leave and take photo. When they say a few weeks later its mouldy you have proof it wasn’t when you left and it must be their fault for not opening premises after you left.

I say this as a landlord who is to kind to tenants.

Do a letter to the landlord /agent informing them of the damp and you dont want them to hold you responsible when you come to leave or deduct sny money from your deposit.
Really needs checking with a damp meter to see the cause, like faulty doc, etc. Not your responsibility to paint defects. The Landlord could paint it with damp proof paint.
If you want to try painting it use any egg shell paint, tht is the same.

Hg mould remover is excellent

Presumably there is no heating downstairs as all the rooms are upstairs?

It is possibly just because it is cold then. I would just keep wiping it as you are doing now. If it is only in that area then I wouldn't go to the expense of buying and running a dehumidifier.

Spring is on the way and hopefully some warmer weather! (edited)

HG Mould Remover Spray is meant to be very good at removing mould and, just as importantly, preventing it from coming back.

If it works as advertised, you shouldn't need to re-paint the area.

From the picture it looks like it comes from the outside. I would do nothing except to go after the landlord and make clear to him that he will get trouble with any health issues comming from that. (edited)

HG mould cleaner helps. Is there any reason why there is no heating downstairs? what is downstairs?

Op, it's great you're letting air in/out daily for half and hour. Be aware, if it's wet outside then you may be drawing moisture indoors! Need adequate heating but I understand that is out of your control. What's on the outside? Any leaky gutters? Or maybe some damaged pointing (mortar between brickwork). It's great you've drawn the landlords attention to it. Best to catch the problem when it's small. As others have advised, I'd definitely put it in writing to him (if only to prove it's here, you've informed him, and that this issue is not within your control).

Get yourself a dehumidifier?

the best way to stop the mold is wipe the walls / area using neat bleach. it will stop it for 2-4 weeks. the cheap thin bleach from asda is great just use it neat .

OP how long have you been there? Is this your first winter?

Do you know what the temperature of the wall and air is?