awful humidity indoors

[Marasme]

we re up North; the humidity inside the house is between 75 and 88% (we have several small humidity meters around the place).

I have a dehumidifier which i run for a few hours everyday to bring the humidity down to 65% in selected areas (mostly my bedroom), said humidity climbs back up to >75% in the morning.

we don t dry laundry indoors
we don t have long baths or showers (we tend to shower at the gym)
the house temp is 16-17 degrees, with the occasional morning blast of heat to 18-19c, and wood burner fire once or twice a week.
we have a new roof
we have new windows
no obvious leak

where does it come from? is it normal?
i m finding it extremely puzzling, annoying and ... uncomfortable

Do you have air vents?

soem have small ones one the windows, are they open?
Are the air bricks open and working?
Sometimes the render outside is defective and can cause this also.

Do you air the house?

Might have poor ventilation

How old is the house? Does it have any insulation? What is it built of?
Do you open windows every day?

Same temperatures here,house build of sandstone so absorbs the moisture,no cavity wall insulation (in fact,no insulation at all).

Windows opened every day,humidity between 50-60%

North Scotland so much colder and wetter than anywhere else in UK

yes, air vents on the windows all "open" all the time, and windows get open upstairs once a day a least, with patio doors more often downstairs for the dog to go in and out. Saying this, humidity outside must be fairly high also as it is constantly raining?

good point about the air bricks... i have no idea. The render is fairly old and we need to sort it next.

What is the humidity outside?

You need a better dehumidifier, I’ve got a Meaco Platinum Low Energy 20L that we have to leave on all night through winter or the damp just goes crazy.

This page has good info about damp and humidity - www.oxford.gov.uk/info/20271/guidance_for_private_tenants/1129/preventing_damp_and_mould

house is bricks, built 1930s ish

unclear about insulation - we suspect maybe cavity, but not 100% sure and have not managed to get a surveyor come check...

no loft insulation

Our house has suddenly become very damp and the wooden floors have buckled. For the first time we’ve had condensation inside the windows. I have a humidity checker device and the internal reading is 75%.

I'm having problems too. 1930s house in Yorkshire. I think I have found my problem though, condenser tumble dryer wasn't level and it's leaked quite bad over time.

Fingers crossed you find a solution.

The level in our living room shows at 76%. It's always highest this time of year in our house - when it's really cold in winter it can go down to 45%. The humidity outside is lower between noon and 5pm, but I tend to open some of the windows then. Always open bathroom window after a shower. I try and do washing on dry days, so it's not inside.

condensation dampness, the house is too cold as you are not heating ir properly so damp is getting in the air.

We have the same problem,1930’s semi,Yorkshire also,we have to have the dehumidifier on from 6pm to 6am,humidity last night was 86!I open windows,leave the back door open when I’m cooking,it’s a constant battle,we have only lived here since February,I want to move already!

When the outside humidity is high (because it's raining!) how is opening the windows going to make it less humid inside?

I have windows open when it's dry outside but if it's raining it's surely not going to help?

Humidity comes off you too, from your breath, that’s why the bedroom windows are foggy in the morning.

Op, to avoid condensation dampnes/high humidity the world health organisation recommends 21 in living room and 18 in bedrooms. As a min to keep it at bay you need the house not tp fall below 18 degrees. As the house is going as low as 16 this is what’s causing it. A low even temp of 18 will stop the dampness.

The air outside is damp, the temperature inside the house is cool. The lower the temperature inside the house is, the higher the humidity reading for exactly the same amount of water vapour in the air. Cold air can hold less water than warm air as a percentage of its mass, we measure this capacity as relative humidity, which is what your sensors are showing.

The only way round it really is to warm the house up, or to keep humidifiers going.

We had this and it was horrendous so you have my sympathy! Same situation so v low heating, no drying indoors, showering at the gym etc - we had an excellent Phillips dehumidifier which we ran constantly but still the humidity was horrific.

We were mid terrace and speaking to our neighbours we found that they'd all at different stages had their loft insulated and basically blocked all the air vents up in the loft! Might be worth looking at that?

Humidity !also known as relative humidity) is a percentage, because 100% refers to how much moisture the air could possibly hold. This depends on temperature. So when it is cold and wet outside, the relative humidity may be close ro 100%. But if you bring that cold air indiors and warm it up, suddenly it could hold a lot more water. If it's still only got the same amount of water in, the relative humidity falls, because the warm air could now hold more.

The relative humidity is the main thing that encourages/suppresses mould and mites, and helps laundry dry or otherwise.

When it's wet and not all that cold outside, but not very warm inside, it is inevitable that indoor humidity will be high, because wet outside air can only achieve low humidity if it is warmed up a lot.

So for instance where I am the outdoor air is12 degrees and 91% humidity. When it is warmed up to 19 (my indoors temperature roughly) it is still at 64%. So that is the lowest possible humidity we could achieve indoors without turning up the heating more. Then with us breathing, bathing, cooking etc in the house and adding more moisture to the air our indoor humidity is actually at 69. And we do have the ventilation running, but not at 'howling gale' levels.

If the indoor temperature was lower, 16 or 17 the humidity would inevitably be higher, just because that's air we have around us in this weather.

The only way to reduce the humidity is to increase the temperature but without reducing the ventilation. Which is obviously expensive 🙁.

That said if your humidity remains high even when it is dryer outside (or there is more of a temperature difference between outside and in) there may be another source of moisture , such as rain soaking into the walls, that could be adding to it. This can happen with solid walls, and also with cavity insulation if the pointing is in poor condition and/or you are in a very exposed location.

Do you have good loft insulation? That is a relatively straightforward job that does make a big difference to indoor temperatures, and it is also doable as diy if you are careful (and watch a few youtube videos beforehand probably). Depending on your income/circumstances/location you might also be eligible for a grant

Having re-read your op, 88% in the bedroom does sound awfully high - donyou have rhe vent open, and is the door ajar or a small gap under your bedroom door for a small cross-flow of air? You really do need that in every room that people are in.

1930's house in Yorkshire, we heat to 19 and ventilate well, no issues. But we do have to ventilate well. These houses hold heat, or mine does by comparison to my previous 30 year old home.

Cracked render especially cement render can trap moisture behind it so that may be adding to the problem. If your walls don't have a cavity it might be worth considering rendering in lime, though that does cost more, it helps draw moisture out of the walls.

Also make sure none of your gutters/downpipes are overflowing/leaking and soaking the brickwork

We are in a 1930’s semi, well insulated loft.
The upstairs windows are open a crack in every room 24/7 and downstairs daytime only. We have only ever shut them once when the temp outside was. -18. You may need to keep your windows open far more.

No dehumidifier and never a problem, we dry all our washing indoors.

Do you think the increase in humidity is because we’re not putting the heating on as a result of the increased fuel prices?

If your home is regularly hittting 18 degrees and below, then yes, it is causing damp.

Looks like we are going to have a damp house then because our gas bill for October was £80,that was having the heating on for half an hour in the morning,that’s not every day either,it’s 17 degrees in my house right now.