Insulated lining paper mold.

[DIY67]

I purchased 4mm backed lining paper (Red) from Amazon and stuck it with Wallrock thermal paste. It has made a difference to out outside walls (no cavity) of our victorian brick house. However, just a year later and I can see signs of black mold, but nowhere near as bas as it was. We run a dehumidifier on and off and always make sure the windows are clear of condensation so why is this happening ? It shouldn't. The thermal paste alone should prevent this. It doesn't feel damp or cold to the touch.

My only thought is to spray with something like Zinsser cover stain or Damp Seal before we actually decorate.

 

[JohnD]

You have a condensation problem. The solid brick walls will always be a bit cold, unless you add meaningful insulation, so consider what the sources of damp are that cause the high humidity, and the means to remove ut.

In UK houses the main cause of excessive condensation is wet washing draped indoors or over radiators.

Bathrooms lacking an effective extractor fan

Bedrooms that do not have a trickle vent or equivalent, and where the windows are not opened every morning after throwing back the covers.

Kitchens where the steam from kettles and cooking is not extracted at source

Older houses in particular may also have plumbing and drain leaks, some of them in or under the floor, but these will usually show localised damp patches.

Leaking gutters and downpipes will cause damp patches that can be seen by eye on the outside of the house.

 

[JohnD]

BTW the insulation in your loft is probably between 150mm and 250mm thick. Cavity wall insulation is about 50mm thick.

Roll-on wall coverings of 4mm are not significant.

 

[Collectors]

I get the same problem & lodgers that doesn't help drying clothes in there rooms. I am trying some paint that has a 5 year guarantee against mould, "we will see" It been on the wall for 18 month & no sign as yet. think it was called zinser permawhite & about £25 per 5lt.

 

[DIY67]

We try to eliminate condensation as much as possible by opening windows, dehumidifier etc. On that very corner of the wall is where the guttering (cast iron) is dripping a bit but I doubt it is affecting the inside so much unless making it extra cold. Old houses for you!

 

[JohnD]

On that very corner of the wall is where the guttering (cast iron) is dripping a bit

Show us some pics please

All the way up to the roof and down to the ground.