lead dampcourse disintegration from corrosion
Lead Dampcourse Corrosion
Here’s how lead dampcourses corrode step by step
Aluminium Dampcourse Corrosion Process
Lead has long been used in old buildings as a barrier to stop moisture from rising up through walls. It’s an incredibly durable metal—normally lasting for generations. But even lead can slowly corrode when exposed to the right mix of moisture and salts from the ground.
When moisture rises through brick or mortar, it often carries dissolved salts with it—mostly sodium chloride (ordinary salt). Once salt mixes with water, it separates into sodium (Na⁺) and chloride (Cl⁻) ions. Each ion becomes surrounded by a small shell of water molecules—this is called a hydration shell.
The sodium ion is relatively harmless, but the chloride ion can trigger corrosion. In damp conditions, chloride doesn’t attack lead directly—it interferes with the protective layer that normally forms on the surface of the metal.
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How Salt Can Break Down a Lead Dampcourse.
The lead surface reacts with oxygen in the air or water, forming a thin film of lead hydroxide that normally slows corrosion.
When chloride ions are present, they combine with lead ions (Pb²⁺) that form on the surface, creating soluble compounds like lead chloride (PbCl₂).
This dissolves the protective layer, exposing fresh metal to moisture and oxygen.
Over time, lead reacts further with oxygen, forming lead oxide (PbO)—a crumbly white powder.
This process slowly eats away at the lead sheet, leaving holes and weak spots in the dampcourse. Once that barrier fails, rising damp can spread further into the wall.
If your property is in an area with saline, coastal soil or has a salt water swimming pool near by, corrosion can happen much faster. Periodic inspection by a damp specialist can identify early warning signs before serious damage occurs.
If your building’s in a high-salt spot, keep an eye out our Rising Damp Injection Products can solve the issue.
