Efflorescence

[Lard]

@Lard I will take your Terry Brown and raise you Steven Boniface:

Stephen Boniface, former chairman of the construction arm of the Royal Institution of Chartered Surveyors (RICS), has told the institute’s 40,000 members that ‘true rising damp’ is a myth and chemically injected damp-proof courses (DPC) are ‘a complete waste of money’.

Additionally.

https://www.heritage-house.org/damp-and-condensation/the-fraud-of-rising-damp.html
and lastly :The rising damp myth - whitworth

There is more evidence against than for the case of rising damp.

 

[baldkev]

Ok, lets suspend this one.... ill update after ive gone round there and taken all comments into consideration. I appreciate the help and everyones advice

 

[Arnold J]

Ok, lets suspend this one.... ill update after ive gone round there and taken all comments into consideration. I appreciate the help and everyones advice
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[Arnold J]

Hygroscopic salts?

 

[mr rusty]

I have first hand experience of this. The moisture causing the efflorescence is quite likely coming from the room itself. The structure becomes salt-poisoned through reactions of combustion products with building materials. The salts are hygroscopic, and when wet trades are applied easily migrate to the surface while the plaster or whatever dries. On the surface they continually pull moisture from the air and grow crystals.

I have had pretty good success around my fireplace by stripping to bare plaster then painting first with a dampseal paint (ronseal dampseal) - not to keep the moisture in, but to stop room moisture getting at the salts. In hindsight, I would have tanked the bare bricks with SBR slurry before plastering.

Going back a few years also originally had uncowled chimneys and agree this is a source of wet chimneys.

 

[baldkev]

I have first hand experience of this. The moisture causing the efflorescence is quite likely coming from the room itself. The structure becomes salt-poisoned through reactions of combustion products with building materials. The salts are hygroscopic, and when wet trades are applied easily migrate to the surface while the plaster or whatever dries. On the surface they continually pull moisture from the air and grow crystals.

I have had pretty good success around my fireplace by stripping to bare plaster then painting first with a dampseal paint (ronseal dampseal) - not to keep the moisture in, but to stop room moisture getting at the salts. In hindsight, I would have tanked the bare bricks with SBR slurry before plastering.

Going back a few years also originally had uncowled chimneys and agree this is a source of wet chimneys.

Unfortunately sealing cob walls can be quite detrimental and this is a very old cottage. Thats not to say it isnt hygroscopic action, but it was happening to the original sirfaces, which is why the customers had it hacked back and replastered. Again, i havent exposed it to see what that plaster job consists of....

Thank you, kev