Mould prevention

[JohnD]

I understand OP to mean he has lightweight concrete block walls. It is possible that they are solid, depending on age. Don't know how old they are or how thick the wall, which would help us.

Lightweight block, or even breeze, is bound to have an external render. If dry, it will have better thermal perforamce than a 9" brick wall.

 

[Matt42]

Thanks johns!, its a lesson for me listening to you guys! the walls are very very cold in winter but then why would the mould just form only in places rather than smothering an entire wall i.e. At the bottom just above the skirting with the corners being worse? Also, when I moved in I noticed in places the wallpaper was more faded in some areas than others and now i realise that previous owners must have been mould spraying the areas i am now spraying!

A dehumidifier on constantly in winter is a worse scenario than a weekly spray of three walls with demoulder! There must be a solution.

 

[Matt42]

Breeze block just a guess, drilling is a nightmare. How can I find out? i could upload a picture of my house but its just covered in white pebble dash.

 

[Burnerman]

Basically if you want to find out if your wall is a cavity, you drill from the outside with a masonry drill just longer than the brick thickness.....if it runs into space then its a cavity, but a few holes should be drilled just to make sure.
The mould is occurring where the air is completely still - behind beds etc.
On a large wall face, air is moving constantly over it.
So - no wet towels or drying washing in that room - if the bathroom is nearby, make sure the extractor is working and used.
John

 

[Matt42]

There can't be cavity, I haved drilled deep enough for tv arm brackets and not hit that soft spot when drilling through, the soft bit is the plaster and then drilling is a nightmare, hammer drilling and tough drill bit! Yeah, no clothes drying upstairs and I put the extractor fan on longest setting in bathroom. Would some photos help?

 

[JohnD]

could do. Especially of the unplastered blocks e.g. in loft. Also the inside and the outside of this wall, showing the gutters, and any downpipes, drains, outside taps, adjacent sheds, flues, WC overflows. How old is the house? When you drill it, what colour is the dust?

also please measure the thickness of the wall (at a window or doorway)

 

[Johnmelad]

. How old is the house?

I My house was built in 1912.

 

[foxhole]

There can't be cavity, I haved drilled deep enough for tv arm brackets and not hit that soft spot when drilling through, the soft bit is the plaster and then drilling is a nightmare, hammer drilling and tough drill bit! Yeah, no clothes drying upstairs and I put the extractor fan on longest setting in bathroom. Would some photos help?

Drying clothes ANYWHERE in the property will cause problems.
Moisture does not sit in one room.