Humidity levels in a loft

Polin_ka · 23 November 2019 at 1:39PM

Hi,

I just wondering what are the acceptable humidity levels in a loft. We've just moved into a house and the loft is so much more humid than the rest of the house with between 70%-80% readings. The upstairs rooms are below 50%.

Not sure if matters but the house is in Scotland and the outside is obviously wet and dump in November.

Jackmydad · 23 November 2019 at 1:56PM

First question to ask is what's the humidity outside?
If the ceilings are insulated, to let as little heat into the loft as possible, and it's ventilated as it should be then what you have is basically a covered outdoor space, so the humidity won't be that different to outside.

shortcrust · 23 November 2019 at 2:15PM

It’s worth remembering that relative humidity - which is what meters show when they give a percentage figure - is related to temperature. A colder room will have a higher humidity reading than a warmer one even if there’s the same amount of water in the air. My basement consistently has a higher RH reading that the rest of the house despite the air usually being drier according the dew point measurement.