Damp salt refers to chloride and nitrate salts of sodium (and sometimes calcium) that cause dampness in buildings. These salts are hygroscopic, meaning they readily absorb moisture from the air, or even deliquescent, meaning they absorb so much moisture that they dissolve.
Why Damp Salt Causes Problems
The presence of damp salts is a common cause of dampness issues within buildings. Here's a breakdown:
- Hygroscopic Nature: Damp salts attract and retain moisture from the atmosphere. This makes walls and other surfaces feel damp, even when there isn't an obvious source of water intrusion.
- Deliquescence: Some salts are deliquescent. They absorb sufficient moisture from the atmosphere to dissolve and form a solution. This can make surfaces perpetually damp.
- Invisible Threat: Damp salts are often invisible to the naked eye, making them difficult to detect until the effects of the dampness become apparent.
- Humidity's Role: The dampness caused by these salts is exacerbated when the humidity is high. The higher the humidity, the more moisture the salts will absorb.
Identification and Solutions
Identifying the presence of damp salts often requires professional testing. Solutions typically involve:
- Removing the Source: Eliminating the source of the salt contamination is crucial. This might involve addressing rising damp, penetrating damp, or condensation issues.
- Salt Neutralization: Applying chemical treatments to neutralize the salts.
- Physical Barriers: Installing physical barriers to prevent the salts from migrating to the surface.
- Specialized Plasters/Renders: Using breathable plasters or renders that allow moisture to evaporate without damaging the surface.
In conclusion, damp salt are chloride and nitrate salts, most commonly of sodium, that absorb moisture from the air, causing dampness in buildings and requiring specific treatment strategies.
