What is efflorescence?

Efflorescence is the process by which salt migrates to the surface of a porous material where it forms a coating (also called Calcium Carbonate or limestone) The appearance of efflorescence is often described as a white, fluffy or powdery substance, but it can range in color from white to gray, brown, or even yellowish hues, depending on the type of salts present. This can be an aesthetic concern. To identify efflorescence, look at the brickwork on walls, masonry walls, or concrete surfaces, it occurs when water evaporates and leaves behind salt deposits on the masonry which are brought to the surface. Water, rain and snow are the primary sources of moisture and may impact the degree of efflorescence.

Efflorescence can happen at different times. It can either be a problem from the beginning of a building’s construction, or the process can occur over time. Primary efflorescence can appear within the first 72 hours of the building materials being used where excess moisture is present. Secondary efflorescence is due to external moisture issues and water penetration which extracts salts to the surface of the building materials.

Installation problems which may lead to efflorescence:

  • Using masonry materials that are not fit for purpose or of poor quality, these salts can easily migrate to the surface
  • Improper ground storage of building material for example damp soil or ground moisture
  • Use of masonry without sufficient ventilation
  • Use of masonry in areas that lack a proper moisture barrier
  • Joint material failure
  • Improper construction techniques could lead to structural damage
  • Environmental factors and climatic conditions, such as high humidity, heavy rainfall, or frequent freeze-thaw cycles.

How to troubleshoot efflorescence

  • Assess the affected structure: is the building old or new, how old is the brick wall
  • Check out the building material condition i.e cracks that could lead to efflorescence (calcium carbonate)
  • Observe the location of efflorescence to determine the water source
  • Check masonry surfaces for moisture and any possible sources of contamination by soluble salts
  • Consider other external water sources i.e condensation within a wall, faulty drain pipes

Preventing efflorescence

While it is difficult to completely prevent efflorescence, good site practice will help to minimize the occurrence.

  • Properly cure concrete after it has been poured, this will help prevent the formation of efflorescence
  • Bricks should not be placed directly on the ground to prevent water from getting into the materials
  • Mortar should be protected from damp contamination and moisture
  • Mortar that is not cleaned may lead to efflorescence(salt deposits)
  • Newly built brickwork should be protected from the elements in the first week to prevent efflorescence

How to remove efflorescence

Efflorescence is temporary. In most cases it will disappear in a few wet winter months in this country, therefore the best solution is often to let it wash out naturally. However, there are some tips for removing efflorescence effectively.

  • When treating an outdoor wall, make sure the temperatures will be above freezing all day
  • Simple washing can sometimes remove efflorescence
  • Scrub the affected area with a wet sponge or brush and plain water. Always be sure to rinse thoroughly, if you leave dissolved salts on the surface, they’ll return as new efflorescence.
  • Watch out for clay. Clay naturally has a high salt content, therefore removing efflorescence in this way is often only a temporary solution – wet weather can bring salt back to the surface again.
  • Using a stiff scrubbing brush and a dry brushing technique, this will remove the efflorescence.

If efflorescence is causing you problems, contact us for expert advice.