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.

 

[DIY67]

Show us some pics please

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

I can't get the whole house in shot so just the affected corner in the bedroom. As you can see the bricks aren't wet. It's a crisp frosty, sunny day. There is a little dripping in rainy weather from the corner guttering but nothing severe.

I put the paper up on all the outside walls in Oct 2023 and it seems to have done the trick. This corner was fine until now and the black mold is getting worse. Especially behind the books and objects on the shelf I put up. I used Wallrock thermal paste and 4mm paper. Before I hung the paper the normal painted lining paper got white mold. Now it's black!! Is there anything I can spray over it like mold paint or something ?

I run a very good dehumidifier regular (its been running all night ) but the area still feels damp even though the polystyrene. This shouldn't be happening!!!

 

[JohnD]

Where is the damp patch in relation to the gutter and downpipe in your pic, which you mention drips in rain?

 

[Koolpc]

Thats condensation....

4mm is not thick enough as insulation on an outside facing wall.

Plus, room needs better ventilation.

 

[DIY67]

Thats condensation....

4mm is not thick enough as insulation on an outside facing wall.

Plus, room needs better ventilation.

Yes but there is a dehumidifier running which should attract the condensation due to being the coldest point in the room. Other parts of the house with this paper seem fine.

I could put another layer over the top with plenty of thermal paste ?

 

[DIY67]

Where is the damp patch in relation to the gutter and downpipe in your pic, which you mention drips in rain?

Pretty much the whole length of the corner but you can see where the window is. We were going to decorate this Spring and tackle the window sill etc so please ignore it. This was the wall before we hung the paper when in the process of removing old lining paper. We did treat the area with mold killer and Thermal paste kills mold anyway.

You can see we haven't lined the windowsill area yet. We do have windows open regular to air the room.

 

[DIY67]

Same downstairs but not as bad. Still, the outside was storm dried and dry rods in base. It seems any objects in the way seem to cause more damp.

 

[Jurassicspark]

get a humidity meter from ebay cheap as chips and will tell you what needs doing.

 

[DIY67]

Yes I have 3 around the housr, as well as one inbuilt on the dehumidifier. They only tell you the humidity, not the source of it. They are also pretty useless as if it's high % outdoors it's very hard to keep it down in the house, even with a dehumidifier. I agree though it seems to be condensation. We can't really have windows open in freezing weather so these are the next best option.

 

[Jurassicspark]

How much is it reading?

. They are also pretty useless as if it's high % outdoors it's very hard to keep it down in the house,

Rubbish.