Efflorescence is a French word, meaning ‘to flower out’ and while at first read you might think it’s a lovely term that glides off the tongue, sadly the presence of efflorescence can be an indication of damp or moisture problems in your property. Moisture in your property where it shouldn’t be (such as trapped in walls or coming up from the ground) can soon become a structural issue with brick and wood weakening over time from the exposure to dampness.
What is Efflorescence?
Efflorescence is the name given to the powdery-white salt deposits that appear on external and internal walls when moisture is absorbed into the construction materials before evaporating from the surface. The salts (typically sulphate salts) come from the natural minerals found in groundwater but also from within construction materials such as bricks, masonry, stone and mortar. These are porous materials, meaning that water can ingress naturally via osmosis which is why it’s important to keep your damp proof course maintained and prevent bridging of cavity wall spaces.
As the salt deposits collect, osmosis increases as water move towards the salt to reduce the concentration. This creates additional pressure within construction material, causing damage to both the structure and durability. This pressure can even lead to building materials separating in a process called spalling.
After the winter, you may have noticed that efflorescence is out in force and a number of buildings are displaying white powdery brick salts. This is due to the increased heat inside of properties during the winter while it remains cold outside. The warmth pushes against the moisture held in construction materials and forces it to the surface, where it evaporates and leaves behind the unsightly salts.
Efflorescence itself isn’t dangerous or harmful to humans, however, the greater the sulphate salting, the greater the volume of water being pulled through and the more damage that is being done to your structure. Efflorescence can also be unsightly as the white patterns expand over brickwork and flake off, leaving a mess on the ground.
What Are the Causes of Efflorescence?
Certain conditions need to be met before efflorescence will occur on surfaces;
Water can come from natural sources, such as rain, snow and high humidity but groundwater wicking and even condensation can contribute to the presence of efflorescence in your property. Although linked to seasonality, with increased efflorescence expected during the autumn and winter months when it’s more likely to rain, snow and sleet, it can still occur during the warmer months, particularly if there is a building fault.
Building faults can be the improper use of materials, such as through-wall flashing or insufficiently ventilated masonry and failing to add proper moisture barriers. It can also occur because materials were not properly stored during the construction process and were left exposed and on the ground where it is able to soak in moisture from the soil, the air and the weather. Materials should always be stored on pallets so they aren’t resting on the unprotected ground and covered with a waterproof sheet.
How do I Identify Efflorescence?
Efflorescence is identified as a white powdery substance that is found on unsealed surfaces such as brick and cement. It can sometimes appear grey but it is more common to misdiagnose a stain or even mould as efflorescence. The key differences are;
Other materials that can be prone to efflorescence include;
Different salts occur in different materials and choosing the right materials for your project can help to reduce the amount of efflorescence that occurs naturally and protect properties from extensive structural weakness.
Brick salts include;
Cement-brick reactions produce the following salts;
Finally, mortar carries salts such as;
Can I Prevent Efflorescence?
It is possible to prevent efflorescence from occurring completely. However, the process needs to be undertaken prior to any construction even taking place which makes it difficult to monitor that safeguards have been put in place throughout.
Storing Materials Correctly
Many homeowners wonder what they can do and how to stop salt coming out of their walls but once a property is constructed it can be difficult to prevent it completely. Before a property is constructed, materials need to be stored properly from purchase to the delivery and must not be stowed directly on the floor or uncovered while not in use. Additionally, construction should be undertaken by professionals who understand the importance of storing materials properly and keep up to date on local weather conditions.
Using the Right Materials
The type of grout used in construction can contribute to preventative measures. Particularly grout with mechanical vibration or chemical additives known as admixtures that will both reduce the frequency of voids in the grout.
Proper damp prevention involves careful planning during construction to ensure a Damp Proof Course (DPC) is installed (a moisture-resistant protective layer that prevents ingress of moisture by capillary action AKA rising damp) between the ground soil and building materials. It also includes the installation of protective overhangs such as copings, eaves and flashings which redirect rainwater and moisture away from external walls and brickwork.
Sealing Building Materials
After construction, an impregnating hydrophobic sealant can be used to cover the surface and prevent the ingress of moisture. A silicone-based penetrating sealer is the best method for preventing brick efflorescence, while elastomeric or polyurethane type paint that acts as a surface plug and sealer should be used for cement blocks. Both types of sealer work excellently at preventing moisture from being absorbed from the outside or travelling from within the material outwards.
How to Remove Efflorescence From Brick
Fortunately, once efflorescence occurs, you don’t have to put up with the unsightly white salts on your external walls forever and it can be quite simple to remove. Although, if you are cleaning away efflorescence or removing efflorescence from external walls, you should aim to do so during a dry, warm day when the sun is out. As the salts that cause efflorescence are soluble, often the white patches will disappear after rain but if deposits are left on the surface, it can soon return.
Brushing the Affected Wall
This can be the most effective way of ensuring no salt deposits are left behind while cleaning your wall and prevents the reintroduction of moisture. Using a strong brush, give the surface a firm cleaning to remove the efflorescence, it shouldn’t take too long although it will depend on how much of your wall has been affected.
A cleaning staple used by many to remove tough stains, diluted vinegar can also be used to remove efflorescence from your walls and is a product you are already likely to own. Diluted vinegar is preferred over professional cleaning products as it contains fewer harsh chemicals and is safer for homeowners to use.
A high-pressure wash can quickly remove efflorescence from your walls but you will need to dry the wall afterwards so moisture isn’t left to collect and ingress into the brickwork. Any sitting moisture that is left behind will soon lead to efflorescence recurring and it becoming a cycle of remove and regrowth.
Should I Worry About Efflorescence?
Efflorescence that occurs in properties less than a year old can simply be a natural occurrence that happens due to the salts in the cement and the water that was used in construction and is often not a cause for concern. For established properties over a year, the presence of efflorescence can be an indicator of issues in construction and should be followed up by an inspection.
Inspections should cover investigation of potential leaks, holes or areas for moisture ingress and will take note of the location of the efflorescence which can indicate where the source of the issue lies. Faults with window and wall joints, roofing and flashing can all be contributing factors to the appearance of efflorescence but can also be the source of a greater issue that requires repair before the property becomes a victim of damp, potentially leading to wet or dry rot and structural weaknesses. Efflorescence is commonly seen where overflow pipes leak onto brickwork, resulting in long, thin pyramid shapes of white sulphate salting.
Laboratory tests on the efflorescence may be required to identify the types of salts appearing on the wall which can help diagnose the source of moisture if it isn’t immediately obvious. This includes improperly placed garden sprinklers and irrigation systems, broken or leaking external pipes and condensation occurring from heating pipes which can all cause temporary sources of moisture that isn’t consistent.
Damp Proofing from Garratts Damp & Timber
If you have noticed recurring efflorescence on your walls with no signs of an obvious leak or source of moisture, you may require the service of a professional damp-proofing company.
Garratts Damp & Timber have over 16 years of experience handling problems with damp, timber issues and providing basement tanking services to properties in London and the Home Counties. Book your free survey with Garratts Damp & Timber today or get in touch with our team on 0208 535 7536.