Salt-Contaminated Plaster: Why It Must Be Removed

If you're treating rising damp or any form of moisture ingress, the plaster on the affected walls almost certainly needs to come off completely. Here's why — and why cutting corners here guarantees failure.

What Happens to Plaster When Walls Get Damp?

As moisture moves through masonry, it carries soluble salts from the ground, brickwork, and mortar. When this moisture reaches the plaster and evaporates, the salts are deposited in and on the plaster. Over time, plaster becomes heavily salt-contaminated.

Why Is Salt-Contaminated Plaster a Problem?

Salts are hygroscopic — they absorb moisture from the air. This means that even after a damp-proof course has been installed and the structural cause of damp has been resolved, the salts in the old plaster will continue to pull moisture from the atmosphere. The wall will remain damp, decorations will fail, and mould may continue to grow.

What Must Be Done Instead

1. Hack off all plaster to the full extent of salt contamination (usually at least 300mm above the tide mark)
2. Allow the wall to dry
3. Apply a salt-resistant renovating plaster specifically designed for use after rising damp treatment
4. The renovating plaster contains additives that prevent salts migrating to the surface

Using the Right Materials

Standard finishing plaster is not suitable for replastering after damp treatment. Specialist renovating plasters (such as those in the Sika or Remmers ranges) are formulated for exactly this purpose.

Shadbolt Plastering uses the correct materials for every damp replastering job. We don't take shortcuts that will come back to haunt you.