Sign of Damp

Is Efflorescence a Sign of Damp? Know the Warning Signs




What is Efflorescence?

Efflorescence is a crystalline residue that forms on building surfaces, typically appearing as a grey or white powdery substance, sometimes appearing like salt crystals.

It occurs when water seeps into building materials, dissolving salts and carrying them to the surface, where they are deposited as efflorescence.

While efflorescence doesn’t always mean severe damp problems, ignoring it can lead to further damage to the structure and building material if left untreated. This is because it can be a telltale sign of penetrating damp, rising damp or other moisture problems that can lead to issues with your property’s structural integrity.

How Efflorescence occurs: salt deposits and water migration

Efflorescence occurs when water infiltrates building materials through capillary action, dissolving soluble salts and carrying them to the surface. The soluble salts can come from various sources, including the building material itself, the soil, or the water used in the construction process.

In masonry, efflorescence can occur when the materials used contain soluble salts, such as calcium, magnesium, and potassium.

Is efflorescence harmful?

Efflorescence may not be harmful in and of itself, but it can indicate a larger moisture problem that can cause serious damage to building materials over time. Examples of this are rising damp, penetrating damp and faulty or incorrectly installed damp proofing.

The excess moisture can cause porous building materials such as brick and wood to weaken and deteriorate, leading to costly structural damage.

Causes of Damp

Rising Damp: Water Rising from the Ground

Rising damp occurs when moisture enters the porous materials in ground level walls through capillary action, often due to a build-up of liquid around the base of the wall and in the ground. Rising damp often occurs when the groundwork around the house is lower, this causes water runoff to gather around the base of exterior walls and absorb into the brickwork.

Porous material like brickwork or concrete can absorb water with dissolved salts, which can lead to salt deposits on the external and internal walls.

Penetrating Damp: Water Entering through External Walls

Penetrating damp occurs when water enters the building through the external walls due to faults in the property’s design, such as cavity wall tie failure or poor pointing. Unlike rising damp, this is higher up the external wall and visible signs include damp patches and salt higher up the wall than rising damp.

The root cause of penetrating damp needs to be addressed to prevent sever damage and efflorescence.

Other Sources of Excess water

Groundwater wicking and condensation can also contribute to the presence of efflorescence in your property.

Building faults can be the improper use of construction materials, such as through-wall flashing or insufficiently ventilated masonry, and failing to add proper damp proof course.

Identifying Efflorescence

Visual Signs: White Salt Deposits, Staining, and Discolouration

As moisture evaporates, efflorescence often appears as a white or greyish salt residue on a buildings porous materials such as brick walls, concrete, paving stones, stucco, and other building surfaces.

Odour of Efflorescence

Efflorescence can cause musty odours and damp smells as water evaporates, but the salts themselves smell a little like sea water.

Peeling Paint and Damaged Finishes

Efflorescence can lead to peeling paint and damaged finishes, as the moisture causes paint and wallpaper to lift, peel and flake off.

Common Areas to Find Efflorescence

Basements and Crawl Spaces

Efflorescence can commonly be found in basements, attics and crawl spaces, where moisture tends to accumulate.

Chimneys and Fireplaces

Efflorescence can also occur on chimneys and fireplaces, where moisture can enter through cracks and crevices.

Other Common Areas

Efflorescence can occur on external and internal walls, particularly in areas with high humidity levels such as bathrooms.

The Impact of Efflorescence

Damage to Foundations and Structures

Ignoring efflorescence can lead to severe cases and structural damage to the property, as damp causes building materials to weaken and deteriorate.

Health Risks from Mold and Damp

Efflorescence can lead to health risks, as excess moisture creates an ideal environment for mould growth. Mould and damp can cause respiratory issues and trigger allergies.

Reduced Property Value and Saleability

Ignoring efflorescence can reduce property value and saleability, as it can indicate underlying damp-related issues. Buyers may see this as a risk to their investment.

How to Treat Efflorescence and Prevent Return

Scrubbing and Cleaning Methods

Removing efflorescence will not cure your efflorescence problems. However, if you have addressed the underlying issue and wish to get rid of the salt deposits from your walls, scrubbing with a strong brush and water can remove efflorescence from the surface of a material.

Chemical Cleaners and Pressure Washing

Chemical cleaners purchased from a local DIY store can be effective for removing stubborn efflorescence, while pressure washing can remove efflorescence from outdoor surfaces.

Sealing and Waterproofing Solutions

Sealing building materials with an impregnating hydrophobic sealant can prevent the ingress of moisture and reduce the risk of efflorescence. Additionally, the correct installation of damp proofing can stop damp in its tracks.

Controlling Moisture and Humidity

Controlling moisture and humidity levels can help prevent efflorescence by reducing the amount of water available to migrate through building materials. A professional damp survey can help you to understand where your dampness is coming from and save your building from excess water, damp and the structural damage that could be caused by it.


Efflorescence Warning Signs and Dangers

Efflorescence is a warning sign of serious damp-related issues, which can lead to severe structural damage if left untreated.

Importance of Addressing Efflorescence Promptly and Repairing the Damage

It is essential to address efflorescence promptly to prevent further damage and reduce the risk of costly repairs. Contact Damp Surveyors Ltd today for a professional damp survey to find the root cause of your issue.

Table of Contents

Picture of Sam Fitzgerald – CSRT Damp Surveyor

Sam Fitzgerald – CSRT Damp Surveyor

Author – CSRT Damp Surveyor
Sam is a highly qualified and seasoned damp surveyor with over ten years of specialised experience. With a strong academic foundation in building surveying and numerous professional certifications, Sam has established himself as an authority in the field of damp diagnosis and remediation.

At Damp Surveyors Ltd, Sam applies his extensive knowledge to help homeowners across the UK address and solve their damp issues effectively. His approach combines cutting-edge techniques with a commitment to honest, client-focused service, ensuring that every survey and recommendation is tailored to the specific needs of the property.

As a thought leader, Sam’s insights into damp prevention and treatment have been featured in industry publications, underscoring his role as a trusted expert dedicated to maintaining the integrity and comfort of your home.

Testing device for measuring dampness in a house


At Damp Surveyors Ltd, we stand out as your premier choice for damp survey services in the UK. Our commitment to excellence and customer satisfaction sets us apart. Here’s why you should choose us:

  • Exclusive 3 Free Quotes: We offer a one-of-a-kind optional service where you not only get our top-notch damp survey but also receive 3 free quotes from vetted local companies, giving you peace of mind by saving you thousands on getting the most competitive quotes, and also time researching and contacting other reputable companies.
  • Knowledge and Experience: We provide unmatched knowledge to every survey we conduct thanks to our team of seasoned professionals and years of industry experience. This guarantees accurate assessments and practical solutions.
  • Nationwide Coverage: Whether you’re in a bustling city or a rural area, our services extend across the UK, making us accessible wherever your property is located. Choose us for nationwide reliability and excellence.

Choose Damp Surveyors Ltd as your reliable partner for all-inclusive survey needs. Our top concerns are the health and safety of your property, and we are committed to providing outcomes you can trust.

Damp issues in the attic of a house

Why Is My Attic Damp?

Key Takeaways Causes of Attic Damp: Attic damp occurs during winter and transitional spring months due to warm, moisture-laden air from the house rising into the attic. The collision between warm

Read More »
A garage filled with water

How to Stop Damp and Mould in the Garage?

Key Takeaways Identification of Damp and Mould Issues: Common signs include wet patches, leaks, cracks, musty odours, and flaky plaster. Issues may occur behind tiles or cabinets, making identification challenging. Removal

Read More »
Damp surveyor explaining house survey to prospect buyer

How Do Surveyors Check For Damp?

How Do Surveyors Check For Damp?   Key Takeaways Role of Damp Surveyors: Damp surveyors conduct a detailed visual inspection of the property during their investigation. They identify two main

Read More »

Our Services

Related Posts