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What Is Efflorescence?: The White Powder on Your Basement Walls

efflorescence on wall

Look at the image below. Have you ever seen this white, powdery substance in your basement? This chalky stuff is called efflorescence, and it’s more common than you might think. Despite its simple appearance, efflorescence is actually a sign of water intrusion. Taking it seriously and calling professionals for a closer inspection can save your home from water damage in the future. Let’s explore why efflorescence appears, how it’s formed, and what it can tell you about your basement.

What is Efflorescence?

Efflorescence is a crystalline deposit that usually appears on concrete, brick, stucco, or natural stone surfaces. It is made of salts that are left behind when water evaporates from masonry materials. These salts look like white or gray powder and can be seen both on floors and walls. Although efflorescence on its own is not a major issue, apart from the fact that it is visually unappealing, it can indicate that there are other, more serious problems such as an internal structural weakness. In either case, efflorescence can give homeowners quite a headache. Let’s take a closer look at this crystalline deposit and ways to prevent it. 

What Causes Efflorescence? 


Efflorescence is caused by a process that begins when water seeps through porous materials like concrete, brick, or stone. Water often dissolves and absorbs salts that are naturally found in these materials (or in the soil surrounding them). Eventually, the water evaporates and leaves these salt deposits behind. Over time, these deposits build up and become visible as a white, powdery substance, which we refer to as efflorescence.

The amount of efflorescence can change with the seasons. It’s more common in wetter months when there’s a lot of water to dissolve the salts. In drier months, the water evaporates faster, so the salts often don’t make it to the surface before the water is gone.

Efflorescence depends on three things: soluble salts, water, and a path for the water to reach the surface. This is why you often see efflorescence on materials that are frequently exposed to water, whether from rain, sprinklers, or groundwater, and especially in areas where the structure has cracks, gaps, or is just naturally porous.

Primary vs. Secondary Efflorescence 

There are two types of efflorescence. Primary and secondary efflorescence are both forms of the same phenomenon, but they occur at different stages of a material’s life and under slightly different conditions.

  1. Primary – Salt deposits that appear on the surface of materials like concrete, brick, or stone due to water used during the initial curing or drying process.
  2. Secondary – Occurs after the material has already cured or dried and has been in use. Often the result of external water sources, like rain or groundwater, that penetrate the material, dissolve internal or external salts, and then carry them to the surface as the water evaporates.

Both types of efflorescence require salt, water, and a path for the water to travel. However, to summarize, the main difference is that primary efflorescence comes from water used in the original mixing and curing process, while secondary efflorescence comes from water that the material is exposed to after it has already hardened and been put into use.

How to Remove Efflorescence 

Efflorescence itself isn’t going to pose a health threat to you or your family, it’s just salt. However, efflorescence is a bit of an eye sore so removing it can make your basement look and feel cleaner. Here are the best ways to remove efflorescence.

1. Simple Washing 

Efflorescence that is newly formed is still very soluble. Using a stiff brush, a bucket of water, and a mild detergent (as well as some elbow grease) should be enough to scrub the efflorescence off your walls. When you are done, grab a hose and rinse everything thoroughly, so that salts are completely removed. Otherwise, efflorescence might reappear in a couple of months. 

2. Power Washing 

If you have a pressure washer in your home, you can use it to remove efflorescence. With pressurized water, you can get rid of white deposits quickly and effectively. However, make sure you use the widest-angle tip so you don’t damage the surface. If the surface is damaged, it can actually leave the wall more susceptible to efflorescence. 

3. Chemical Cleaning 

If efflorescence has been on your wall for a while and it cannot be washed away with soap or the pressure washer, you will need to get acidic cleaners. Follow the instructions thoroughly and make sure you soak the surface with water before you begin with cleaning, otherwise, the cleanser might penetrate the surface and open new pores.

Apart from acidic cleaners, you can use diluted citric acid, vinegar, and muriatic acid as well. After you have removed the efflorescence, neutralize the acid with a baking soda solution and rinse the surface with water. If you opt for this solution, be sure to wear protective gloves and goggles, so that the acid doesn’t hurt your skin or eyes. It is always recommended to try the gentle methods before you send in the cavalry. 

How to Prevent Efflorescence 

Efflorescence, though often not directly harmful, signifies a larger problem for buildings and structures: water intrusion. To avoid extensive water damage, it’s best to take preventative measures with the help of professional waterproofing services. Let’s discuss a few strategies professionals may employ.

  • Architectural Adjustments: Implementing changes like installing a gutter system can help channel rainwater away from your home. This prevents water from collecting near the foundation or walls, reducing the chances of efflorescence appearing.
  • Landscaping Adjustments: Consider the lay of your land. Your yard should slope away from your house to ensure water drains away instead of towards it. If you’ve got flowerbeds close to your home that need regular watering, it might be worth relocating them to prevent constant soil saturation near your foundation.
  • Surface Sealants: Application of a hydrophobic sealer can prevent moisture from penetrating walls, reducing efflorescence. However, this is often a temporary solution and might need regular reapplication.
  • Encapsulation: Particularly useful for homes with crawl spaces, encapsulation involves installing a vapor barrier to prevent moisture from seeping in. This keeps the area dry and less prone to efflorescence.
  • Drainage Solutions: Sump pumps and below floor drains are popular ways to remove water buildup in your basement. Basement drainage captures water quickly and prevents it from sitting on porous surfaces for too long.
  • Grout Admixtures: These can be added to improve grout flow and reduce the porosity of construction materials, making them less likely to absorb salts and contribute to efflorescence.

Efflorescence might appear no matter where you live — Alabama, Mississippi, Georgia, or Tennessee. If you’re dealing with this issue, don’t hesitate to contact professionals like AFS for a free inspection. With their expertise, they can pinpoint the cause of the efflorescence and recommend reliable, effective solutions.

Efflorescence FAQs

To permanently remove efflorescence, addressing the root moisture problem is essential. Simple cleaning won’t prevent recurrence. Professional solutions like those offered by AFS involve identifying and sealing moisture entry points and managing indoor humidity. This comprehensive approach ensures a lasting resolution and a healthier basement environment. 

Not necessarily. While efflorescence does indicate the presence of moisture, it doesn’t always signify a severe problem. It could be due to minor, easily fixable issues like slight condensation or minor leaks. However, professional assessment is recommended to rule out major underlying issues. 

Have you ever noticed a white residue on your crawl space walls? That is efflorescence, and while it won’t harm your walls on its own, it is often a sign that there are moisture problems in your crawl space. 

Why Does Efflorescence Appear? 

White or grayish stains on your masonry walls can leave you confused and worried. Luckily, this crystalline deposit is efflorescence, and it shows up when water from the bricks begins to evaporate. On its way out it collects salts, and leaves them on the surface of the brick or concrete. These stains will not compromise your home’s structural integrity in any way, but they can be a sign of underlying foundation problems. Excess water can end up in the building materials in multiple ways. In some cases, there is excess water in the concrete mix itself, other times sprinklers, underground seepage, and roof runoffs can lead to efflorescence. 

Increased humidity levels in the crawl space can also cause efflorescence. When moisture-laden air enters the crawl space, it causes condensation to form on the masonry walls. Those moisture drops are then absorbed into the porous materials. 

How Can a Dehumidifier Help? 

Efflorescence is often a telltale sign that there are high moisture levels in your crawl space. To prevent those unsightly crystalline deposits from appearing on your walls you should take the necessary steps to keep your foundation as dry as possible. 

With a dehumidifier, you can remove excess moisture from the air. Therefore, apart from preventing mold and mildew growth as well as wood rot, you can prevent efflorescence from showing up. Of course, you will need a strong and efficient dehumidifier that is powerful enough to dry out your crawl space. To make sure you choose the best dehumidifier for your needs, contact your local contractor and see what your options are. 

Holly Richards-Purpura

Holly Richards-Purpura

Content Writer

Holly is a Content Writer for Groundworks who has written and edited web content for the foundation services industry for almost 10 years. With a background in journalism, her passion for the written word runs deep. Holly lives in Columbus, OH, with her husband. Along with educating homeowners, she also has a big heart for the Big Apple.

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