Humidity questions

[Tlandcruiser]

I have a temperature gauge with a built in humidity meter which has been reading quite high, yesterday it was reading 79% (outside weather app said 99%) and today its reading 62%. Searching Google suggests 50% humidity is what the house should be, but how is it possible to have a house with 50% humidity if the outdoors humidity is 99%? how does the outdoor humidity levels effect the indoors humidity?

Today, the temperature is 14c with a humidity level advertised as 62% could the house be lower than that?

I have no damp or mold, the windows do get a little condensation but I put that down to being old double glazing with large windows..most of the windows are almost 3m long and quite tall.

The kitchen does not have an extractor fan, so I know that will contribute to the humidity unless the window are open to ventilate. My small bedroom window is open 24/7 as I like the room to be cold, the back door is open alot but I could ventilate other rooms more. The oven is gas with a gas hob, so that til will increase the humidity.

House Details:

1960s detached bungalow with a suspended wood floor
Cavity walls
double glazing
No damp/mold
Gutters are clear and I dont have water sitting by the house nor is the dpc bridged anywhere

Im not sure what else to check? or is it a problem? I dont want to buy a humidifier,

Edited by Tlandcruiser on Tuesday 22 October 15:51

[Tlandcruiser]

Equus said:

Firstly, there is no 'magic number' for relative humidity. Unless you use air conditioning (which can control humidity levels by condensing out the moisture from the air) it will be what it will be.

Secondly, however, what you're measuring is relative humidity; ie. the percentage of the total amount of moisture that the air can hold.

Air can hold more moisture when it is warm than when it is cool, so if you take external air at (say) 90% humidity and warm it up inside your house, its capacity to hold moisture increases, therefore the relative humidity figure drops as it warms up.

But so long as you don't have noticeable problems with mould or condensation, don't sweat it.

Thanks Equus,

So on days with lots of rain and high humidity, the indoor level will be higher too and my gauge is only displaying how much water the air can hold before it condensates??? so the actual humidity level could be lower?

The meter did suprise me because I do not get mold or damp issues which I did associate with high humidity

[Tlandcruiser]

98elise said:

I thought fk that's low...then checked where you lived!

50-55% indoors just about perfect in the UK, but unless your getting condensation/damp then it can go quite a bit higher without issues.

How is it possible for a house to have readings that low? Even in my last house I had high levels.

[Tlandcruiser]

I’ve been reading a lot on the subject and gaining a bit more understanding.

I think the majority of the humidity is due to lifestyle and not ventilating the bungalow enough especially the kitchen where so much humidity comes from due to the lack of extractor ( plan on extending and moving the kitchen) otherwise I would have installed one already.

Repealed round the double glazing as the silicone looks pretty bad and maybe allowing rain in..

Loft has no soffit vents and just lap vents, I don’t know if that might impact it?? But I’ll add soffit vents.

I wanted to lower it because if I add a rimless aquarium, I don’t want to increase the humidity to much

[Tlandcruiser]

prior to cooking the humidity was 60%, once my wife started cooking with the window open it still rocketed to 80% before I stopped measuring. I'll fit a cooker extractor because the planned kitchen/extension is not until next year or in two years time. Then that mositure rich air gets circulated around the bungalow quite quickly as its only 100sm.

[Tlandcruiser]

Just an update to my situation;

After convincing my wife to air the house out in the mornings, she now opens the front and back windows to create a through draft. My house humidity sits mostly between 60-62, but through the day can show 58 -64 depending on cooker use, (no cooker extractor at present time) its been as low as 52 when I have been at home and ventilated more than my wife.

Partly I realised our last house was very old, drafty, cold and had a PIV unit so we never really opened the windows and never needed too! so its just been a lifestyle change.

Im ordering my fish tank for my office, which may increase the humidity as its open top, so I may install a PIV from nuaire. However, i'm also having the chimney opened back up and the fire reinstated as the previous owner had it blocked up, so that should improve the ventaliation and may not require a PIV. But its good to see the improvement in air quality.

[Tlandcruiser]

Just further updates to my situation - in case someone searches and finds similar issues.


Kitchen hood has been installed with an external vent
Gutters cleared out - lots of crud and water sitting in the gutter blocked by moss and dirt.
Bathroom extractor fan vent had a mesh bug screen and was restricting quite a lot of flow - removed completely and just left the Louvre

Humidity now averages 58, I suspect will gradually drop lower. Pretty happy with that. I might still fit the PIV as the benefits still seem appealing.