Qu'est-ce que l'efflorescence sur la maçonnerie?
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What is efflorescence on masonry?

Understanding Efflorescence on Masonry

Efflorescence is a term that might sound unfamiliar to many, but its presence is commonly observed on masonry surfaces. It's that white or greyish crystalline deposit that occasionally forms on building surfaces, particularly on unsealed ones like brick. But what exactly is it, why does it occur, and how can it be managed?

What is Efflorescence?

Efflorescence is a crystalline deposit of salts that can form when water is present on building surfaces such as bricks, concrete, and other masonry materials. This phenomenon is not just a cosmetic issue; it can indicate potential moisture problems within the structure. The name "efflorescence" is derived from the French word "to flower out," which aptly describes its appearance as it can spread quickly if not addressed.

Causes of Efflorescence

Several factors contribute to the formation of efflorescence:

  • Water-Soluble Salts: The primary culprits behind efflorescence are mineral salts, often calcium carbonate. These salts can be present in the masonry materials themselves or can be introduced from external sources.
  • Moisture: For efflorescence to occur, there must be a source of moisture that allows the salts to dissolve. This moisture can come from groundwater, rain, or even from the masonry construction process itself.
  • Atmospheric Conditions: The evaporation of water on the masonry surface leaves behind the salts, which crystallize and become visible.

Preventing and Controlling Efflorescence

Prevention is always better than cure. Here are some measures to prevent efflorescence:

  • Quality Masonry: Using high-quality masonry materials that are less prone to efflorescence is a good start. This includes materials that have been properly cured and have minimal soluble salts.
  • Moisture Barriers: Installing moisture barriers can prevent groundwater from coming into contact with masonry materials.
  • Proper Storage: Masonry materials should be stored off the ground and covered with waterproof materials to protect against groundwater and precipitation.
  • Landscaping: Ensuring proper drainage around the building can prevent water from pooling and seeping into the masonry.

Removing Efflorescence

If efflorescence has already formed, it's essential to address it promptly:

  • Assessment: Before any cleaning, assess the affected structure. Observe the location of the efflorescence to determine the water source causing the issue.
  • Cleaning Solutions: Mild cases of efflorescence can be treated with diluted vinegar and brushing. For more severe cases, specialized efflorescence removers may be required.
  • Rinse and Repeat: After applying the cleaning solution, it's crucial to rinse the area thoroughly. This three-step process—rinse, apply the cleaning solution, and rinse again—ensures optimal results.


Efflorescence, while common, should not be ignored. It's a sign of underlying moisture issues that can lead to more significant structural problems if not addressed. At Maçonnerie Montréal, we pride ourselves on our expertise in masonry and our commitment to ensuring the longevity and beauty of your structures. Whether you're dealing with efflorescence or any other masonry-related concern, we're here to help.