To wonder what the heck is up with my indoor humidity levels?

[housemover2019]

Not the most exciting of topics I know.....moved into our house in April. I have a hygrometer from the days of my DS's childhood asthma when I used to keep an eye on his bedroom temperature and humidity levels. It's now sat on a dresser in my bedroom and has shown humidity levels around 50% since we moved in. In the last fortnight this has increased to between 65-70% and I have no idea why! Seems to be elsewhere in the house too and not just confined to our bedroom so a dehumidifier wouldn't really sort it unless I bought one for every room! I've noticed slight condensation on bedroom windows a few mornings but nothing else. Bedroom windows are open about 80% of the time and are kept slightly open overnight.

House isn't old (20 years) and a quick google search suggests problems with leaks amongst others. But leaks where?! Would this be obvious or something I'd need to get a plumber to check?

Anyone any experience of a sudden rise in indoor humidity levels?

Don't know if this helps at all but my Nest app is saying it's 66% humidity in my house (SW England)

(And it hasn't been this high previously)

Plumbers have a gadget. Maybe you could get one to scan your house with his gadget.

Thanks @floorboards. I'm in NI. Really don't think it's weather related so is very strange.

Ha @frogspawn. What is this gadget you speak of?!

Bumping for a morning crowd!

It’s a humidity measuring gadget which they can move around the room and it does the gadget equivalent of hide and seek support, saying hotter, hotter no colder, yes hotter...

Thanks Freda...

You hold it against walls and ceilings. If it suddenly bleeps and gets all excited, you’re near the leak/damp spot

One of the reasons I discovered I couldn't rely mainly on the humidity sensor to control my bathroom fan is that outdoor humidity in the UK is frequently far above the target level we're supposed to want in our homes. By "frequently" I mean when it rains. I hear NI has rain.

(My humidity sensor worked as intended as though-out the winter, then soon after the heating went off and the windows were opened, the fan started running non-stop, and I had to reset it to a level where it makes a negligible contribution to keeping the fan on. I've put the timer to maximum overrun to compensate.)

Take you humidity meter outside and see what it measures. If it's not much different to inside, your house isn't the problem.

Oddly my dehumidifier is working overtime today. Must be something in the air

Take you humidity meter outside and see what it measures. If it's not much different to inside, your house isn't the problem. Obvious and yet brilliant :)

As well as rain outside, presumably this is partly because it's cooler? RH is relative humidity, not an absolute measure. Hot air can hold more moisture than cool air, so the same absolute amount of moisture in a space gives a higher RH reading when it is cooler - you're nearer to the maximum amount it could hold.

And the fact that air can hold less moisture when it's colder is why we get condensation on cold windows and outside walls.

Condensation on windows is caused by temperature change. So happens on sunrise and sunset, as the temp change is extreme at this time of year.
This will probably relate to the levels in your house, and if you have no ventilation the moisture will never escape.
Have you got your heating on? May help to keep it at a stable temp 24/7 inside. Depending on size of house a dehumidifier can do the whole lot, it works for me but I have a 2 up 2 down 50sqm place.
I find the south facing rooms have no issue with condensation and damp, the north facing rooms are horrendous so I keep the dehumidifier in those. Otherwise i get black mould growing in the SE corner which is an outside wall.
If the weather outside has high humidity such as in rainy warm weather there won't be a lot you can do about it inside without a dehumidifier. If you do have air vents you could consider blocking them to see if it helps but only if safe to do so (not if you have real wood coal or gas fires).

Thanks all. I get that when it's wetter/cooler it's more likely to increase but I've used a hygrometer for years - humidity levels in last house never rose above 50% regardless of time of year (same age of house) and it's only been very recent that it's increased here in new house. When we moved in it was colder than it is now so have just been trying to work out what (if anything) is causing a sudden increase.

What kind of house is it, does it have proof insulation, brick walls with no cavity? Air vents? What kind of glazing? Detached/terraced?

Not sure about the other insulation, but it's brick, detached, double glazing......

And is that similar or different to your old house?

I noticed when we put in loft insulation humidity was crazy, same happened in parents house.

Main difference to last house is in size - this one's much larger. Insulation wouldn't really explain sudden change though - we've been in the new house almost six months and this has only started in last two weeks.

the weather has turned the last couple of weeks.
we have the same here, higher humidity the last ten days or so since the weather turned to shit

I think freda means a protimeter.

I got back from a sunshine holiday on Sunday and have practically had my ventolin inhaler in my mouth permanently since landing which is very usual for me unless I have a cold (I don't). High humidity does play havoc with my breathing so this is interesting and a bit of a relief.