A mystery of the damp cold room in the house

[spader]

I monitored with a digital weather station the small room (about 3x 3 m) in downstairs, and it seems strangely keep having high humidity up to 75% and 13C constantly last few days. The electric heating has been switched off with the spring coming, and outside temperature here has been about 8 - 14C lately.

In the other rooms same without the heating, all about 17-18C and humidity of 55 - 63%. Why is the room has such high humidity and colder temperature than the other rooms in the same house? The window is facing north hence it doesn't get any direct sunlight during the day. But then right straight up there is a room above it which has same direction of the window facing north, and has 16C and humidity of 60% in most time.

The small room was a dining room originally in this house, but it was sectioned into 2 parts and the 30% of the space had been made into a shower room and W.C. It has a wall and wooden door between the shower room W.C. and the room has a cupboard for the drinks and a bookshelf with the old books beside the walls.

Any ideas? Thanks in advance.

 

[Ivor Windybottom]

Relative humidity is temperature dependent. If you took the air from a warm room with low humidity then cooled it down without adding any water then its relative humidity would increase. Warm air can absorb more water. The absolute humidity hasn't changed, but the colder air is less capable of holding moisture so it's a greater proportion of this lower amount.

It's likely that the room is just cooler as it's north-facing. The room above it will get heat from the neighbouring rooms and through the floor void so is less cold.

Try sealing the room up and heating it, you may see that the humidity reduces to a similar percentage to the rest of the house that's a similar temperature. If so then there's nothing to worry about.

 

[spader]

Try sealing the room up and heating it, you may see that the humidity reduces to a similar percentage to the rest of the house that's a similar temperature. If so then there's nothing to worry about.

Yeah, it sounds right. Will keep the door opened for some ventilation, and put on the heating for next few days, as the night temperature is dipping down to almost 0C this week. Will see how it goes. Many thanks for your info and advice. cheers.

 

[JohnD]

Shower?

How is the water vapour ventilated away?

 

[spader]

Shower?

How is the water vapour ventilated away?

The shower room has a vent fan on the wall opening to the outside space. And the window in the shower room gets left open during the day.
But still I can see the shower room is damp. The metal shelf for the toiletries bought about 3-4 year ago has gone much rusty all around in the shower room.