Salts in wall

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My house was badly renovated in the early 90’s using dabbed on plasterboard and gypsum skimm on the inside and cement rough cast externally. The house is constructed of stone.

i am slowly moving through the house using the appropriate materials.

i have a patch of salts coming through a wall inside that I have plastered using nhl3.5 and painted with auro. This particular part of the wall is of concrete block and I suspect that rain is getting in somewhere. It is the weather wall and gets hammered this time of year being on the west wales coast.

just wondering if there is anything I can do before I hack off the outside to remedy the salts?

Justine Changed status to publish February 17, 2020

Salts have an expansive force of around 2.1 tonnes per m2, so they can and will breakdown any material which they come into contact with. So whilst there are solutions to prevent salt growth, these are not generally advised as they also prevent moisture movement.

Salts are somewhat difficult and need to be managed, they require moisture to form, but a wall also needs to breathe. Salt growth occurs in two forms –

  1. Efflorescence – this is where the salt growth occurs on the face of the material, whilst it looks unsightly, it is a positive as the growth occurs on the face and isn’t taking place within the substrate.
  2. Cryptofflorescence – this is where the salt growth occurs within the material, this can cause long term damage as it can breakdown the building material. This occurs when moisture movement is restricted.

Measures can be taken externally, as you have mentioned, to try and reduce water ingress which can limit salt growth.

If you’d like to discuss this further please contact us on 01208 79779

Justine Changed status to publish February 17, 2020
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