Updated: Nov 7
Many homeowners and builders in the UK will be familiar with the sight of a white powdery substance appearing on the walls of their properties. This is known as ‘salt efflorescence’ and is a sign that there is moisture within the building materials of the property. It spoils the look of brickwork and painted masonry walls and attempting to paint over the affected area is pointless until the source of the moisture has been identified and eliminated. Although harmless in itself, it needs to be dealt with in the correct way to avoid further moisture-related problems in the future which can cause more serious structural damage. It is therefore considered good practice within the building trade to deal with salt efflorescence as soon as it is noticed. What is ‘salt efflorescence’ ? Three conditions must be present for this white substance to appear:
There must be water soluble salts present somewhere in the materials used in the construction the property.
There must be sufficient moisture in the wall to render the salts into a soluble solution.
There must be a path for the soluble salts to travel through to the surface of the walls, where the moisture will then evaporate, leaving behind the salts. The salts crystallise and cause the sparkly, white residue which is a familiar sight to many
Research suggests that mineral salts are contained naturally within many of the building materials used in the construction of homes and properties and on their own, they are not a cause for concern. It is when they come into contact with moisture that the problems arise. For efflorescence to appear, the salts must be dissolved into a solution by water. The weather provides the primary source of moisture in buildings in the UK, although condensation, groundwater wicking and interior activities may also impact on the moisture content of a building. If no water reaches the salts, they cannot themselves become soluble and migrate to the surface. All three of these conditions must exist before salt efflorescence appears so the key to dealing with it is to stop water from infiltrating the masonry walls. Efflorescence will only stop forming when moisture is prevented from interacting with the naturally occurring salts and turning them into liquid form. Unless the source of the moisture is eliminated, it is highly likely that the cycle will continue and the efflorescence will continue to appear, despite efforts to stay on top of removing it. Although it is possible to brush and clean the affected areas of an external wall, this only gets rid of the visual signs of salt efflorescence and does not unfortunately cure the problem – it simply removes the symptoms. After cleaning, the salt efflorescence will reappear unless the ‘cycle’ that created it in the first place is broken. The very fact that salt efflorescence has appeared shows that mineral salts are present within the construction materials so the most effective way to stop them dissolving and travelling to the surface of the walls is to prevent further moisture from penetrating the masonry. The answer is NOT to seal the walls however. Applying sealants onto areas that show signs of underlying moisture or salt efflorescence problems is NOT recommended as any kind of sealing product is likely to either intensify, relocate or spread the problem. This is because such products prevent the moisture within the building materials from breathing out or escaping and this leads to the salt crystals forming beneath the surface of the substrate. As this builds up over time, you can end up with a much more destructive process known as ‘spalling’ whereby the masonry crumbles and disintegrates. This then becomes more difficult and expensive to fix. How can ProPERLA exterior coatings prevent the appearance of salt efflorescence? The panels treated with ProPERLA (right and left) had substantially less salt effloresence than the untreated middle panel, following accelerated weathering testing. The ProPERLA range of exterior coatings can assist with the appearance of salt efflorescence by keeping the walls of buildings and properties DRY. The coatings create a super hydrophobic surface without sealing it so that any moisture that already exists within the building can breathe out naturally and not get trapped under the surface. When it rains, coated building surfaces will repel water – similar in nature to the way a lotus leaf forms beads of rain water. Independent testing on our products have shown that they reduce water absorption by 93.4%, meeting British Standard for Water Vapour Resistance : BS EN ISO 7783:2011. By diminishing water absorption, ProPERLA exterior coatings have been proven to reduce the cycle whereby soluble salts within bricks and mortar migrate to the surface where the moisture evaporates leaving behind the crystals. As a result, the products slow down the ageing or breakdown of the surface of the building by helping to protect it from the worst of the weather, including wind driven rain, frost and sea salt penetrated air. Any property coated with one of our exterior coatings will be weather protected for up to 25 years.