Salt attack
Salt attack: deterioration of masonry caused by soluble salts crystallising within pores, spalling the surface. Linked to rising damp and DPC failure in Australian homes.
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Salt attack (also called salt fretting or sulphate attack) is the physical deterioration of masonry materials caused by soluble salts crystallising within the pores of brick, mortar, or render. As moisture carrying dissolved salts moves through the masonry and then evaporates, the salts recrystallise and expand, exerting pressure that fractures and spalls the surface material over time. Salt attack is visible as pitting, flaking, or powdering of brick faces or mortar joints, typically in the zone just above the damp-proof course level where moisture concentration is highest.
The mechanism is closely related to efflorescence: both are caused by salts in solution, but efflorescence deposits at the surface while salt attack occurs within the pore structure of the masonry. Both indicate a moisture pathway, usually a failed, bridged, or absent DPC or blocked weep holes. Salt attack damage is typically irreversible; affected bricks must be replaced and the moisture source remedied.
Also known as: salt fretting, sulphate attack.
Category: Masonry / defects / waterproofing.
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Last updated: 2026-05-10. Verified: 2026-05-10.