Damp in bathroom - better fan or dehumidifier?

[MyNameIsInigoMontoya]

We have a big moisture issue with our bathroom at the moment - it is starting to get mould not just on the ceiling but also coming down the walls round the window, and I'm wondering what's the best way to deal with it.

Current situation is we have a wall extractor fan, relatively new, says on the box 100mm and 21 l/s (Xpelair one, with humidistat and timer) but it doesn't seem to help enough. It doesn't seem to extract enough, and seems to stop before it's fully dry. Unfortunately as we're usually rushing out in the mornings I don't get to open the window enough either, and this time of year the heating doesn't come on much (fairly well insulated house) so the damp is just hanging around.

I'm thinking we either need to upgrade the fan again (DH will moan about this though, but I did question whether this one had enough power when we got it...) or consider a dehumidifier - but I'm not sure about that as there's no really good place to put it, so it would be standing around in the middle of the floor and getting in the way. (Also seems to cost more!).

Would you agree that beefing up the fan further is the first thing to try? Or any other suggestions? Thank you!

start with the extractor.

If the room is already damp, you can run it continuously until the windows stay mist free. After that, run it whenever the room is used (the light switch is a good way to arranger that) and experiment to see how long a run-on you need. If it is running throughout your bath or shower, there should not be condensation, but it will need to run while the tray and wet towels are drying. A small fan often needs 20 minutes, but yours is more powerful so should be quicker.

Keep the window shut while the fan is running so that it can create enough suction to draw in air from the house through the gap under the door. That fan is powerful enough to work even if the door is slightly ajar, you need a flow or air into the room and out through the fan duct.

If the fan is working well, you can even hang washing over the bath, and it will remove the water vapour (without extraction, this would be a terrible source of damp).

Super helpful as always, thank you PigletJohn. Will start with the extractor and get the electrician booked in pronto.

Window is a non opener, which I am sure has not helped the situation...And just to say, you are indeed correct that builders fit the most ineffectual basic extractors #thingsiwishiknew