Humidity/Damp advice

ripplyuk

I’ve lived in this house for 7yrs and last summer, the indoor humidity was much higher than normal with no obvious reason. I have two humidity monitors in the house and both were showing 70-85% (Normally in summer they would show around 50-55% and lower in winter). The same thing happened the previous summer too but not to the same extent. It got so bad last summer that the wallpaper was falling off and everything smelled of mould. 

This is a council house so I reported it to the council and they said they’d send a damp specialist out. I told them it’s in summer that the problem occurs but it has taken so long, the damp specialist only arrived yesterday. He didn’t see any problem since the humidity was fine. All he did was go round the walls with a damp meter. 

I told him it would be better if he came here in summer when the humidity is higher but he said I was wrong and that humidity is always at it’s highest in winter. I thought perhaps he was being very technical about relative humidity/absolute humidity etc but he said they are ALL higher in winter. He then said he has a degree in environmental science and that this is his ‘area’ etc so I didn’t ask anything more. Is he right? I’m really confused now. I thought warmer air could hold more water and it certainly always feels more humid in summer. Winter is when my skin is dry and I get chapped lips. 

Does anyone have any idea what could be causing this? It happened suddenly. The house was never in the slightest bit damp before. Obviously, I don’t do anything stupid like drying clothes inside. I’m very careful about ventilation etc. With it being winter, the indoor humidity varies between 45-60% which although in the normal range, is still higher than it used to be in this house so I think the problem is still there but not as obvious as in summer. I spoke to another damp specialist on the phone last year and he suspected a leaking pipe (like a very slow leak) somewhere but the guy yesterday said it can’t be that because it would be worse now since ‘the pipes are used more in winter’, which I don’t really understand. 

kobe84

Winter is when you have your heating on in the house and with all the windows closed and very little ventilation it's not surprising that the humidity will be higher.

stuart45

Humidity outside is normally higher in the summer than winter, but condensation problems are usually a winter problem.
October to April is known in the trade as the condensation season.

ripplyuk

@kobe84 Mine is lower in winter. Much lower. Maybe it’s because I still open the windows regularly. All the windows have trickle vents too. 

@stuart45 That’s what I thought. That’s it’s higher in summer. I don’t have any condensation problems that I’ve noticed. There might be a tiny bit occasionally on the front door but I’d expect that since it has single-glazed glass. 

stuart45

If the air outside is warm and humid, it will be the same inside naturally, but the walls will normally be above the dew point temperature.

ripplyuk

@stuart45 The outdoor humidity here in summer is commonly 80-90%. I was checking the dew point temperature too and I would assume the walls were above that but since it was summer, and warm, I didn’t have any heating on. It’s not just the wallpaper though. I found mould on clothing, bags etc. This is despite running a dehumidifier whenever the windows were shut.