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When water evaporates from building materials, it takes the salts from masonry to the surface where they form a crystalline deposit called efflorescence.

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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. 

efflorescence on wall

What Causes Efflorescence? 

When for some reason there is too much water in the concrete mix, it tends to evaporate. On its way to the surface, vapor carries soluble salts with it. There are various reasons why there is suddenly unwanted moisture in the concrete, from underground seepage to sprinklers and roof runoff.   

Through the pores in concrete, brick, and masonry, vapor carries dissolved salts to the surface and leaves a powdery residue. The denser the materials, the harder it is for water to reach the surface. 

Efflorescence can appear due to seasonal weather changes. It is more common during the rainier months when excess water can find its way into the concrete. On the other hand, efflorescence rarely occurs during the drier months.  Since low humidity speeds up water evaporation, salt deposits are left unseen. However, high humidity levels slow down the evaporation, which means that there are higher chances that salts will leave a trail in a form of efflorescence. 

Three factors that play an important role in the appearance of efflorescence are soluble salt, water, and channels. Some of the salts that can be found in masonry materials are table salt, sulfates, and silicates. In addition, alkalis such as calcium hydroxide form salts in contact with air. The sand and gravel from which concrete, patio blocks, and mortar are made, contain natural salts. 

Primary vs. Secondary Efflorescence 

There are two types of efflorescence, primary and secondary. Primary occurs when the building is still fresh. During the first couple of months after the construction, the water used to make cement evaporates. It leaves behind a crystalline deposit that will vanish on its own after some time and won’t reoccur. On the other hand, there is secondary efflorescence that presents a bigger issue. It is more persistent and will not just disappear. It happens due to the influence of external concrete poisons like the presence of road salt. These salts create saline solutions that find their way into the concrete garage floors. Secondary efflorescence can occur anytime there is excess moisture, and unless you fix the moisture problem, things will only get worse. 

How to Remove Efflorescence 

If you are not in a hurry to remove the white powder from your concrete, the best thing you can do is wait. In time, foot traffic will remove residue located on the garage floors. When it comes to new buildings, efflorescence will occur on the walls, and the trail will eventually get washed away by rain. However, if you cannot just sit still waiting for the problem to resolve itself, here are several measures you can take. 

A Simple Washing 

If you have just noticed efflorescence on your concrete, it means that the deposits are still new, and the powder is still very soluble. Therefore, grab a stiff brush and a bucket of water, and use a mild detergent to scrub the efflorescence off the masonry materials. In case some stains are particularly stubborn, you can use elbow grease to get rid of them. When you are done, grab a hose and rinse everything thoroughly, so that salts are completely removed. Otherwise, they might reappear as efflorescence in a couple of months. 

Power Washing 

In case you have a pressure washer in your home, you can use it not just to wash your car or your driveway, but also 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. Once the surface is damaged, it can leave the wall more susceptible to efflorescence. 

Chemical Cleaning 

In case the efflorescence has been there 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 

Of course, it is always better to prevent efflorescence from occurring in the first place than to deal with the consequences later. To prevent efflorescence, you will need to call waterproofing professionals. Here are some measures these experts may recommend: 

Architectural adjustments: Installing a gutter system is a great way to prevent water from pooling near your home and entering your foundation or walls. Without excess moisture, efflorescence won’t occur. 

Landscaping adjustments: Your yard should be graded in a way that directs water away from your house, not towards it. If you have any flowerbeds near your home’s perimeter that require constant watering, consider moving them someplace else. 

Surface sealer: A hydrophobic sealer can stop moisture from penetrating the walls, but this is not a permanent waterproofing solution. 

Encapsulation: If you have a crawl space, encapsulation can be a solution you are looking for. A vapor barrier will keep the moisture out. 

Grout admixtures: With grout admixtures, you can improve grout flow and reduce the porosity of materials, therefore making them less prone to salt absorption. 

Whether you live in Alabama, Mississippi, Georgia, or Tennessee, to get to the bottom of the problem contact AFS to schedule a free inspection. Waterproofing specialists will be able to locate the cause of efflorescence and recommend trusted solutions.

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