Efflorescence

Efflorescence is an accumulation of minerals and salts on masonry surfaces, such as brick, cement, and sometimes stone. Efflorescence itself is not dangerous; it indicates the presence of excess water, which can lead to more serious structural and health issues.

How Efflorescence Forms

The earth contains natural salts that are present in the raw materials that make up masonry products, such as concrete, asphalt and stucco. These salts remain trapped within masonry in solid form until they are dissolved into water, which usually makes its way into the material through small pores. Water can originate from rain, sprinklers, household leaks, or any number of other places. Cold, dry air will draw this liquid back out of the material where it evaporates, depositing the salt as a white crystalline growth on the surface. Efflorescence typically forms during cold, dry weather shortly after it has rained and moisture has entered the masonry. It can occur year-round, but it is most likely to form during the winter due to low temperatures.

As with mould, the appearance of efflorescence varies greatly. It can be powdery, it can have sharp edges and be easy to spot, or it can have indistinct edges. It can cover a large area as a fine dust, or form large individual crystals. Its appearance depends partly on the type of salt from which it is composed, but humidity also plays a role in this determination. In exceptionally dry climates, water can evaporate before it even reaches the surface, in which case the salt will accumulate unseen beneath the surface. In humid conditions, moisture may take a long time to evaporate, allowing the slow growth of “whispers” projecting from the surface.

Inspectors should note the presence of efflorescence in their inspection reports because it generally occurs where there is excess moisture, a condition that also encourages the growth of mould. An exception can be made during the first few years of a building’s construction when efflorescence will appear as a result of moisture locked within the masonry in a process called “new building bloom.” This moisture comes from water added during the manufacturing or mixing process that will undoubtedly contribute to efflorescence. This type of efflorescence will appear all over the masonry material and will continue to accumulate until the initial water supply is exhausted, which can take up to a year. Efflorescence that appears locally and after the “new building bloom” is over is a symptom of excess moisture that can be problematic. The source of this moisture should be determined and corrected.

In summary, efflorescence is a harmless yet unsightly accumulation of salts on masonry surfaces. Its presence indicates excess water, a condition that can damage interiors and encourage the growth of mould. Inspectors should know how to remove efflorescence from surfaces, and educate their clients about its identification and significance.