Damp/mould spots on living room walls - help!

[JohnD]

humidity depends on temperature. Your outdoor shelter was unheated.

If you bring cold, damp air from outdoors into the house, and warm it to room temperature, it become dry air, even though the amount of water has not changed.

A cubic metre of hot, dry air in the Sahara contains more water that a metre of cold, damp air in Manchester.

 

[JP_]

Exactly, so, not just a matter of having extractor fans. Must reduce humidity too.

 

[JohnD]

an extractor does a lot of good, because it takes the warm air (with a lot of water vapour in it) outside the house and (unless you live in a submarine) outdoor air, which is cooler and contains less water, comes in to replace it.

sucking the air with the greatest moisture load (typically from a bathroom) reduces the total moisture content of the air in your house. You need to get the moisture out faster than it is added.

 

[mattylad]

We had similar issues (currently all paper removed for redecorating) so we are fitting a trickle vent in the lounge window and a fan will be fitted in the kitchen, to try and reduce this.

 

[EFLImpudence]

not just a matter of having extractor fans. Must reduce humidity too.

 

[JohnD]

you mentioned that you have a water meter. If there is a leaking pipe, especially if it is in or under the floor (kitchen floors particularly) it will cause damp and you might not be aware of it.

get a torch and have a look down the meter pit. There is a glass window (you may have to wipe it) with a bubble that rotates when water is passing through. Turn off all the taps and see if it stops. This is a better indicator than trying to watch the numbers change.

 

[opps]

How old is the property?

Older properties had a slate damp proof course. They do eventually fail. That said, I don't recognise the pattern of patches that you have (unless the decorator did a lot of surface refilling over the plaster).

If the mold behind the sofa was on an internal brick wall then I would be focusing on a failed damp proof course.

If you tape a section of bacofoil behind the sofa and don't see any moisture on the surface later you will be able to discount condensation, especially if the surface under it has worsened.

 

[FrasB]

Please see attached pictures. We have now got little damp spots all over one wall in our living room and now noticing it on other walls. They are small little spots about 5mm-10mm across. Room was replastered last year. First noticed spots a few months ago and has got increasingly worse since - anyone got any ideas what it is, what's causing it, any products I could use to "clean" the spots? Probably also worth noting we are extending the house at the moment (spots started before this), currently have no boiler/heating, and getting condensation on windows. Any help much appreciated! Thank you

Did you resolve the problem? I have something similar. Trying to work out what is causing the issue.