Condensation damp

[Tanito279]

I'm a tenant and have what I think is condensation damp in one bedroom, even though the window is always open. It's on 2 external walls in the room above the kitchen and nowhere near the window. Please can anyone advise on the best way to deal with it? I know no wet clothes inside etc but can I actually make it go away?
Pictures attached. The landlord said to keep the window open and ignore it.

Dehumidifier

Airing is good. Use dehumidifier regularly - with window and door closed. Do you use an extractor hood/fan when cooking or keep window open? If you don't have extractor fan here, using dehumidifier in kitchen when cooking could help a lot. Also, keeping the house heated helps. To get rid of the mould, there are various products you can use. I have always personally found Dettol Mould and Mildew Remover (bright green, trigger spray bottle) very effective and it's available in most supermarkets.

if it is on external walls, it may not be condensation. Have you looked at the walls/roof on the outside? Are the gutters clear and working properly?

We've got the same issue, also on external walls. Landlord says it's from drying clothes inside (not that we've got an alternative) but I'm not convinced.

Do those cheap silica box dehumidifiers work, does anyone know?

yes i agree with others a dehumidifier is essential before it gets any worse. I would recommend you get one of these In the long run you need to take this issue up with the landlord as you don't want it getting any worse.

itssquidstella I've used those dehumidifier balls when dd room started to get a musty smell for no reason. It worked really well I think it's a uni bond one

Yes. We sell the uni bond ones at work.... very effective I'm told

£10 for the unit £6 for refills

Use the cheaper mould & mildew remover spray from Home Bargains.

Spray on microfibre cloth (pack of 5 tesco everyday ones are best value) and wipe over. May need more than one go at it.

Wash cloths in machine to keep for going over it again.

Has your house got cavity wall insulation? Hate the stuff has caused problems on one of my rentals. For your landlord to say "ignore it" is shameful.