Cob Walls - Paint Question

[aynsley dunn]

Hi folks - I'm hoping someone can help me...

We moved into a house which is partly constructed of cob.

We decorated the house as complete novices, using standard emulsion.

Damp spots are now prevalent on the cob areas

I understand that a breathable paint should be used when finishing cob. My question is, do I need to remove the current paint (back to plaster?) before I then add the specialist, breathable paint? If so, are there any products recommended for this?

Many thanks,
Aynsley

 

[JohnD]

Is it condensation?

Or is water entering from a leaky gutter or something? You must fix the source of water.

Do the walls have lime plaster on them?

 

[fillyboy]

There is a fully breathable paint made by a company called Beeck, German, ridiculously expensive and incredibly difficult to use because you need to maintain a 'wet edge' when using it, otherwise it shows where you join to it.
If you've used a proper 'vinyl matt' from a paint supplier or a builders merchant, this will not be breathable, if you've used a cheap contract emulsion (Dulux paint from sources like B & Q is basically contract emulsion), then this is breathable, not as breathable as Beeck, but breathable nontheless.

The good news is that even if you folllowed the 'experts' advice and used Beeck paint, damp spots will likely appear because the walls are porous.

 

[jacko555]

Farrow and Ball Estate emulsion is as breathable as limewash and more than clay.

They have a nicer colour range than clay, in my opinion.

https://www.heritage-consulting.org/is-farrow-and-ball-paint-breathable/

 

[aynsley dunn]

Thanks for the paint advice - much appreciated.

But would I need to remove the current paint before applying new?

Cheers

 

[JohnD]

yes, of course

if it is an impermeable layer, you have to take it off or it will still block vapour.

but, where do you think the water is coming from? you must find it and correct it.