Damp or Not

Contemplation

Background: We recently started renting an upside down house built partly into a bank. Downstairs is more north facing and generally much colder than the completely above ground south facing upstairs.

We like a cool place to sleep and the 15C temperature was ideal. Many experts have suggested that letting a house go below 14C isn't a good idea, but 15C and above is fine, although the government recommends 18-21C throughout for health but admits there is limited evidence for these figures.

The downstairs smelt musty on first viewing but all the windows and doors were open and the landlords said there was no damp but did admit a small patch of mould on an internal stone wall which was behind a piece of furniture. They stated that once cleaned and the air gap increased in size between the wall and item there were no further issues.

Upon moving in the smell was stronger. In the rear downstairs bedroom my leather jacket did devolop mould. Just the other day we noticed mould on the front bedroom curtain on the side nearest the wall where the problem had been with mould prior. It was the curtains and nets that were musty and without them up the room smells fine.

Regardless of the temperature there is never any condensation on the walls, except briefly after a shower in the vicinity of it.

The dry weather over the last few days has been good and the whole house remains comfortably in the 40-60 relative humidity range regardless of whether the windows have been open between readings or not. In fact the aboslute humidity went down over night suggesting the house is adequately ventilated even without open windows in dry conditons. We contribute very little water to the atmosphere based on local government perspiration and respiration averages and personal utiltity company water use report.

However, prior to this dry spell the relative humidity in the house was upwards of 70% and never below 60% despite any measures taken. We do get a lot more rain here as we are in the west of the couuntry for the first time in our lives.

The question: when it's wet outside and the inside is 63% to 78% relative humidity is this just what happens when you live in a very wet area over this period, or is there a structural damp problem? I'd appreciate any thoughts from anyone who has any knowledge or expertise in this area and can factor in the measurements I've taken. Many thanks.

Contemplation

Can I bump the thread to allow it to be seen?

MultiFuelBurner

Bring the house up to temperature and air it and that should sort itself out.

Contemplation

MultiFuelBurner said:

Bring the house up to temperature and air it and that should sort itself out.

The downstairs has been sitting between 15C at nght and 18C during the day. The upstairs is always warmer as it's south facing with big windows. I'm not convinced that it's not at temperature. In all the other properties I've lived in there's never been must, mould or high humidity. This even applies to a north of Scotland property where you would wake up in winter seeing your own breath and where the indoors very rarely reached these temperatures across the whole house during the colder months.

propertyrental

If the downstairs wall back onto soil or into a bank, as seems likely, then penetrating damp is a distinct possibility unless the whole wall has been efficiently 'tanked' ie protected from the exterior soil.

In a 'normal' house built virtically on flat ground, the foundations and base of the walls are below ground which is why a damp proof course is added to prevent the damp soil which is in contact with the walls cannot rise up and cause dampness in the house above ground level.

A damp proof course at the base of a wall which was in contact with soil up its entire height (or at least up to 1st floor level) would serve no purpose - hence tghe need for proper tanking.

Contemplation

propertyrental said:

If the downstairs wall back onto soil or into a bank, as seems likely, then penetrating damp is a distinct possibility unless the whole wall has been efficiently 'tanked' ie protected from the exterior soil.

In a 'normal' house built virtically on flat ground, the foundations and base of the walls are below ground which is why a damp proof course is added to prevent the damp soil which is in contact with the walls cannot rise up and cause dampness in the house above ground level.

A damp proof course at the base of a wall which was in contact with soil up its entire height (or at least up to 1st floor level) would serve no purpose - hence tghe need for proper tanking.

Yes, I do understand all this. I'm just trying to ascertain whether the data indicates damp, walls not being breathable or whether the high relative humidity could just have come from the extremely wet conditions ie the moisture inside isn't going to escape into more moist air through the walls even if breathable. I'm just looking for clues to distinguish between these and any other possibilities. A moisture meter is showing that all the plasterboard is dry. However, the stone(?) walls are measuring high readings low down (ie just above the skirting) but it's no worse on inside walls than on the one that's directly into soil. I know that moisture meters can be affected by salts and so some people think they are very limited and I have to say I'm unsure how a wall would have higher salts along the base region and not higher up if salt distribution was random. The floors all test dry too.

The biggest factor in the humidity is whether it has rained outside or not,even when the doors and windows are closed. At the moment the exceptionally dry air is reflected indoors and RH is sitting at 53% and 56%.

jonnydeppiwish!

Try a decent dehumidifier for a a few months and see what effect/collection you have

MultiFuelBurner

Contemplation said:

MultiFuelBurner said:

Bring the house up to temperature and air it and that should sort itself out.

The downstairs has been sitting between 15C at nght and 18C during the day. The upstairs is always warmer as it's south facing with big windows. I'm not convinced that it's not at temperature. In all the other properties I've lived in there's never been must, mould or high humidity. This even applies to a north of Scotland property where you would wake up in winter seeing your own breath and where the indoors very rarely reached these temperatures across the whole house during the colder months.

With those temps you can run a good (not cheap) dehumidifier to see how much moisture you are pulling out and measure it. See if it improves things.

RelievedSheff

I would try heating the downstairs a little higher see if it has any effect.

All houses require a different level of heating to keep the moisture at comfortable levels. It could just be that with this floor being below ground level and north facing it needs that extra bit of heat.

the_lunatic_is_in_my_head

We live in a house built of stone and find it difficult to heat (without spending a fortune).

In the summer when it's 30 degrees outside the downstairs remains cool, for the last 3 years there has been a period of excessive humidity around October, it was particularly bad this year at the end of September when we had that mini heat wave after a miserable summer, the warm, wet air was sucked into the cool downstairs of the house and then condensed on the stone floors and walls, we had puddles on the slate floor downstairs. 

We do the usual things living wise to keep the house free of excessive humidity but during these brief spells of humid weather other than running a dehumidifier I'm not sure what can be done. 

Same as yourself we get more than or fair share of rain, the house being built into a slope won't help but if you are renting there's not much to be done as I doubt the landlord is going to have it dug out. 

Checking where the down pipes, particularly at the back, soak away to might be worth a look as well. 

Contemplation

jonnydeppiwish! said:

Try a decent dehumidifier for a a few months and see what effect/collection you have

We were running one when the RH was between 63 and 78% (it's recommended to stay within the 40 to 60% range as I'm sure you know). 78% is a lot of extra moisture in the air. This is what started to concern us.