How salt damages masonry
Masonry is porous. When water carrying dissolved salts moves through brick or stone and evaporates at the surface, the salts are left behind and crystallise. As the crystals grow, or take up moisture and expand, they put pressure on the pores and flake the surface away. This is called salt weathering, and it can turn a sound wall into a powdery, crumbling one over time.
Sources of salt
- Sea spray and salt-laden air on coastal properties such as those in Tynemouth, Cullercoats and Whitley Bay
- Rising damp, drawing salts up from the ground into lower walls
- Road salt splashing onto walls beside roads and pavements
- Old contamination in bricks and mortar, such as from previous fires, chimney soot or earlier damp
- Cement-based materials that push moisture and salts into the surrounding brick
Signs to look for
White fluffy deposits (efflorescence), powdery or peeling brick faces, blistered paint, bricks that crumble when touched, and mortar that appears harder than the masonry. Plaster inside that keeps flaking, or damp patches that return, can mean salts are present within the wall.
Repair approach
We look at the source of moisture first. If rising damp, leaking gutters or a hard render is feeding the problem, that must be dealt with or the repair will not last. Then, depending on severity:
- Brush off surface salts when dry, and allow walls to dry out where possible
- Replace brick or stone that has lost its strength with suitable matches, see spalled brick replacement
- Repoint with a compatible lime mortar so moisture and salts leave through the joints, not the masonry, see lime repointing
- Use sacrificial renders or plasters in affected areas inside, where appropriate
Things to avoid
Waterproof sealants and hard cement renders can trap salts and moisture inside the wall and make damage worse. Cleaning with water alone can drive salts further in. A staged approach works best, and we explain what is needed and why.
Related pages include coastal render repairs and basement tanking, since cellar walls are often salt-contaminated. Conservation area rules may apply to external changes; see the Planning Portal.
Frequently asked questions
What is the white powder on my brickwork?
It is usually efflorescence, salts left behind as moisture evaporates. It signals that water is moving through the wall, and the source of moisture should be found.
Can salt-damaged brickwork be saved?
Often, if the damage is limited. Weak bricks are replaced, joints repointed in compatible mortar and moisture sources fixed. Severely decayed areas may need rebuilding.
