Mould and condensation on bedroom windows?

[anothercold]

We live in a rental property, a Victorian terrace. This is the first winter we've lived here. Our bedroom windows are covered condensation every morning, but it gets really cold in the house so we prefer not to have windows open at night. Today I discovered mould on my toddlers window frame, behind the blackout blind. I've cleaned it with bleach spray and opened the windows and done the same in the master bedroom, but after a full morning with the windows open the condensation is still there on the glass. Sash windows if that makes a difference.

Is this normal? I've only ever lived in modern builds before this and never had this. How can we prevent it?

Dehumidifier

You need to leave the window open even just a tiny bit. More ventilation is needed. Also window vac the glass in the morning if it's bad with condensation

Black out blinds are an issue as moisture gets trapped behind them. Are they needed in winter - is there a bright street light? If not it's be better to remove them.

Toddler won't sleep without blackout blinds - we're in a bright city street. However the condensation is also on the master bedroom windows which don't have blackout blinds.

How do you check humidity levels in a home? Is this normal? I don't understand why there's so much moisture which wont go away.

But sometimes / most days in autumn winter the humidity outside is too high. I think the general rule of thumb is that humidity over 70% causes mould.
I try to keep the house below that through using a dehumidifier. I happily switch them off and open windows instead when they humidity outside is below 70 - in fact, I had them all open yesterday - but it’s often not.
It’s not raining today but the humidity started at over 90% this morning and is still 76% according to my weather app so open windows would be counterproductive.

You need to air during the daytime. If you can just lift the sash a little that should be enough and daily wiping away too

Daily wiping and airing. This is not unusual. Just winter.

It’s very normal in older properties. We are in a home that is about 230 years old, single glazed etc and we have condensation on all windows. So do all my neighbours because I notice it when I go out in the mornings.

I don’t have a mould problem but only because I keep on top of it. I ventilate well all spring and summer and in colder and more humid months I use a good dehumidifier extensively. The dehumidifier I bought also tells me the humidity on the control panel which is useful. I also check what the humidity is outside on my weather app to tell me whether opening windows is helpful or not.

Small patches will still appear in odd places etc but I just wipe away when they do - it’s as much part of my cleaning routine as vacuuming would be. We did used to have a real problem in one specific room - and wiping away wasn’t cutting it - until I introduced the dehumidifier. Now that room has no problems whatsoever.

Wipe the windows down with a towel every morning so they're totally dry, that helps a lot.

I live in an Edwardian semi with sash windows. Condensation generally just comes in Winter. We keep on top of this with a Karcher window vac and airing the bedrooms daily.

Karcher window vac
Gentle airing
'Dettol Mould and mildew' spray & gentle wipe down every so often.

Closed windows = condensation, you choices are to open the windows or mop up the condensation every day.

I use a wide windscreen wiper type cleaner and a towel along the bottom of the window which can be dried elsewhere.
We have had very wet but relatively mild weather - colder air cannot hold as much water so the condensation should improve once we get colder winter weather. There might be morning condensation to remove but after that should stay drier.

Agree with all above, open windows in daytime to air out, dehumid for an hour or two morning and evening when windows closed. Leave door open at night. It's a pretty normal.older house problem in the uk. Wipe any condensation with kitchen roll in morning and a good dettol every so often. May I suggest as well, not keeping furniture in the room against any walls, so there is airflow and to check bed slats and mattress regularly.

Remember, the water needs to leave the house.

Whichever way you're keeping control, it needs to be built around that.

Window vac or dehumidifier => water tipped down sink.

Wiping with cloth => wring the cloth out down sink before leaving to dry (indoor drying puts that moisture back into the air).

Open window for 20 mins or a crack all day => indoors air leaves, replaced by outdoors air. So will get rid of some indoors moisture, and outdoors air is usually holding less moisture than indoors air in the UK, with exceptions when it's very wet or humid outside. (NB the amount of moisture are can hold is proportional to temp, which is why taking cool outdoors air and warming it up in the house means the % humidity of that air drops).

Extractor fan in bathroom or kitchen => particularly steamy indoors air leaves, replaced by outdoors air. So will almost always be worth doing because UK outdoors air never as damp as steamy shower-room.

LL here. I'd take photos of it before cleaning it off with bleach. You should tell your LL or agent including which rooms it's affecting from worse to bad.

As a LL | would expect to provide a dehumidifier until the source of the problem was found and remediated. Some landlords would not unless the tenancy agreement so stated - and in the latest scandalous case which led to a child's death the HA just didn't reply.

In my case it was a crack in the plaster on the outside wall which allowed rain and damp in which then seeped into the brick and the inside wall (no cavity just bad 1980s building). Once sealed it stopped.

Worth searching for dehumidifiers online and what they cost to run. The plus side for my tenants was the removal of damp somehow made the flat warmer - possibly loss of damp? Unfortunately a lot of housing, old or new, is substandard. There were speculative builders in Victorian times ....

amount of moisture air can hold is proportional to temp

Oh gosh this is sounding really bad news - what a complete hassle! Wiping every morning etc. I'm really regretting renting an older property.

With a dehumidifier do you put one in every room? Are they large things?

I thoroughly recommend getting a dehumidifier or two. In 20 minutes mine has reduced the bedroom's humidity from 80% to 55%.

Clothes drying indoors, baths/showers, just generally respiration of water from our bodies will cause condensation on windows once it's colder out than in. Just need to keep on top of it.

This is the one I have, OP, although there are many. It has a digital display and automatic function so very useful. It's not very big and is on casters so you can push it from room to room.

amazon.co.uk/gp/product/B073XNK45P/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

Don’t dry clothes indoors, and keep kitchen and bathroom doors shut, put lids on boiling pans…as well as all the rest.

Unless you have a large or awkward house, one dehumidifier should be enough - just read the spec before you buy, as it should say.

Useful info on the Meaco site, regardless of which brand you end up buying (though I use and love Meaco):

blog.meaco.com/dehumidifier-buy-two-bedroom-house-guide/
blog.meaco.com/how-to-choose-a-dehumidifier/

I grew up in a council flat in the 70s/80s, condensation on the windows in the morning, no central heating, etc. We had no window vacuums, no dehumidifiers, and... no mould. What on earth has happened to the standard of housing where dealing with mould is considered a normal part of life?

Thanks @CrunchyCarrot

How long do you run this for each day? Do I have to swap it between the two bedrooms?

I'm annoyed I'm going to have to do this as it seems such a hassle plus extra cost of running it. Not sure if it's landlords responsibility.

What a pain. How do people dry clothes then? We have a washer dryer and no garden, but not everything can be tumbled.

Aaah I want to move back into a modern home