Efflorescence – What Is It & How to Prevent and Remove It

What Is Efflorescence?

Efflorescence is a crystalline deposit of salts often seen on brick, concrete, paving stones, stucco, or other building surfaces. It occurs when water leaves behind salt deposits on or in the masonry surface. It has a white or grey tint and can also appear as a powdery substance on floors or walls. In French, the word efflorescence means “to flower out” and in this case, it is salt that is flowing out of surfaces. If it is not taken care of properly, the issue can spread quickly. Efflorescence is not dangerous, but it can lead to moisture problems causing structural damage to building materials. That is why it is important to act when you spot it.

What Causes Efflorescence?

There are three conditions needed for efflorescence to occur:
1. Water-soluble salts are present.
2. Moisture is available to turn salts into a soluble solution.
3. The material is porous, and salts can move through to its surface, where the moisture then evaporates and causes the salt to crystallize.
The salt may already be present in the brick, concrete, paving stones, stucco, or building surface. It may also be in the grout or cement holding the surfaces together. If the surface is in contact with soil, then efflorescence could form. Efflorescence may occur during home construction if materials are left out overnight and absorb moisture from damp soil and rain. It is often a seasonal problem, usually escalating in winter (when rain, snow, sleet, and other weather conditions arise).

Is Efflorescence Harmful?

It is common for people to confuse mold with efflorescence. Efflorescence itself isn’t dangerous or harmful. It can lead to potential moisture problems that can cause structural damage to building materials. So it is important to take action when you notice efflorescence in your basement, on your paving stones, or on other structures.

How to Prevent Efflorescence

Hydrophobic sealants: to prevent the absorption of water/water from traveling within the building material
Capillary breaks: can minimize the risk of salt entering the material
Quality masonry construction: eaves, overhanging coping, and flashings will minimize the risk of water entering a wall
Being intentional about landscaping and sprinklers: to prevent water from reaching porous building materials
Installing grout with mechanical vibration: this will limit the chance of voids in the grout
Storing masonry materials properly: keep materials off the ground and cover them with waterproof materials to protect against groundwater and precipitation
Utilizing grout admixtures: these are designed to improve the flow of grout mix and reduce its water content simultaneously

How to Remove Efflorescence

The best way to remove efflorescence is dependent on the surface and the composition of salts. Think of these as more of an ongoing solution rather than a permanent fix.
Pressurized water – Dissolve the efflorescence by applying pressurized water. Make sure to dry off the water from the building material after otherwise, the efflorescence may reappear.
Diluted vinegar – It is less harmful than industrial chemicals and it works! Just rub the efflorescence with diluted vinegar.
Brushing – For some salts, you can wash them away with a hand brush, mild detergent, and a rinse.