humidity in bathroom

sniggings

I can understand with showers running etc bathrooms can have higher humidity but even after I have run a dehumidifier and got it down to 45%, over night it creeps back up to around 65% with no showers etc, the rest of the flat is around 50%, no window that opens in bathroom either, is this normal? the walls are well insulated but there is a big window tho, I just can't understand where the humidity is coming from?

PheoUK

what wall/floor coverings?

sniggings

it's a new build, only one outside wall which is very thick, the floor has boards (sorry don't no exactly but not concrete) down, with lino on top.

WestonDave

What heat are you running in the bathroom - relative humidity is a function of water content and temperature - so the same air in a flat heated to 20C showing 50% humidity would show 65% at roughly 15/16C. So if your bathroom is unheated and is therefore generally colder, that alone would explain the reading difference.

sniggings

WestonDave wrote: »

What heat are you running in the bathroom - relative humidity is a function of water content and temperature - so the same air in a flat heated to 20C showing 50% humidity would show 65% at roughly 15/16C. So if your bathroom is unheated and is therefore generally colder, that alone would explain the reading difference.

no heat in the flat at the moment, it's 19c in the rest of the flat with no heating on, but 13c in the bathroom, seems strange there is such a difference, the outside wall is about a foot thick...just noticed tho that the extractor fan has a slight breeze coming through it (it's on the ceiling) it has been very windy tho today, so the extractor could be the problem, is it normal for a breeze to come through extractors?

DRP

Is 65 percent RH high?

I'd love any part of my house to drop that low overnight! ��

I wouldn't necessarily worry as long as you can rule out leaks.

WestonDave

Better extractor set ups either have flaps on the outside that close against the wind when not in use, or have mechanical shutters near the fan that only open when the fan is running. I guess neither are entirely windproof so it may just be the high winds at the moment. Worth however checking for draughts around the pipe outlets as that can also bring in cold air from outside. Big window can cause some cold as glass conducts heat better than stone.

sniggings

DRP wrote: »

Is 65 percent RH high?

I'd love any part of my house to drop that low overnight! ��

I wouldn't necessarily worry as long as you can rule out leaks.

It was just the difference between the bathroom and the rest of the flat I was wondering about more so.

sniggings

WestonDave wrote: »

Better extractor set ups either have flaps on the outside that close against the wind when not in use, or have mechanical shutters near the fan that only open when the fan is running. I guess neither are entirely windproof so it may just be the high winds at the moment. Worth however checking for draughts around the pipe outlets as that can also bring in cold air from outside. Big window can cause some cold as glass conducts heat better than stone.

thanks, guess the humidity and extractor are OK...maybe I shouldn't have bought the humidity monitor for the bathroom!