As a homeowner, you’ve probably seen white crystal-like substances forming in the basement or the crawl space during the wet season. That’s efflorescence. It appears in homes with poor drainage or water seepage issues. Here, we are going to look at what efflorescence is, what causes it, and whether a dehumidifier is of any use.
Efflorescence in your crawl space forms when water migrates from the surrounding soil and infiltrates cement or mortar, carrying with it dissolved salts and minerals. The white residue may appear over a large area, and stain the walls up to a certain height.
Your masonry is porous and will wick in water and moisture from the outside. When this moisture evaporates, the water-soluble ingredients start to crystallize. The resulting residue looks like white powdery stains on your walls.
Prolonged periods of rain and water movement through the concrete will bring salts and minerals to the surface. These combined with carbon dioxide from the atmosphere produces calcium carbonate, a white chemical substance.
Many factors can lead to the formation of efflorescence on your crawl space walls. Wall cracks, negative grading, poor drainage, and excess moisture tops the list. Cracks allow underground water into the crawl space. Negative grading or slope allows water to flow into your home’s perimeter and pool there or enter the crawl space. Excess humidity can lead to condensation. The water beads that form when the temperature drops get absorbed into the concrete. And when the weather warms up, this water moves up and brings with it salt and minerals to the surface.
The best time to remove the white chalky substance is before it combines with carbon dioxide in the atmosphere. Up to this point, the efflorescence will easily dissolve in water and can be dislodged by simply wet scrubbing it. Be sure to rinse the walls or floor with fresh water so no residue is left to dry on your concrete again.
Once efflorescence moves to the calcium carbonate phase, it becomes insoluble and difficult to remove. Try clearing with a mild acid solution such as vinegar (5% acetic acid) or citric acid. If you decide to use Muriatic acid, make sure you dilute it first and gear up.
Acid washing will leave residues that can harm your plants. Make sure you rinse the slab properly and neutralize any remaining acid with baking soda. Other commercial products are available, and these can help you dissolve calcium salts. However, they can also damage your concrete. Be sure to test them out on an inconspicuous part of the crawl space.
If you want to beat efflorescence, you’ve got to address the root cause of water or moisture in your crawl space. This entails improving surface drainage and sealing cracks on your foundation walls. It’s also advisable to have the walls encapsulated with a heavy duty plastic barrier.
Walk around the yard and see if it has a positive grading. If there’s a negative slope, you will have to get a landscaper to regrade it so water flows out instead of pooling around your home’s perimeter. The ideal yard grading should be six to eight inches over 10 feet.
When it comes to efflorescence, prevention is better than cure. You’ll avoid a lot of problems by ensuring your home builder uses a well-graded concrete mix and a water reducer. It’s also important for the concrete to be consolidated properly and applied directly to the vapor retarder. Grading your concrete mix and using a water reducer are instrumental to creating a dense concrete slab. Such a slab will have small amounts of bleed water and a little capillary network. As a result, it will be able to resist water absorption and stop water movement.
The truth is that a dehumidifier does nothing to counter or reverse the effects of efflorescence on your crawl space walls. This device will only help you dry out the crawl space air so moisture won’t build up and cause condensation, mold growth, rust, and other problems. If you’re going to condition the crawl space, we strongly encourage you to get a dehumidifier.
The best way to resolve the issue of efflorescence is to address the underlying problems that give rise to it in the crawl space. We typically use the CrawlSeal™ Encapsulation System, and effective barrier that isolates the crawl space from moisture. This durable system protects your home’s structural integrity while reducing energy costs by up to 25%. Ours comes with a 25 year warranty. Together with the crawl space drains, they may stop mineral-rich water from ponding.
If you’re struggling with crawl space humidity or experiencing water problems in the rainy season, we can help. Schedule a free crawl space waterproofing inspection with the experts at JES Foundation Repair. They will come over and uncover the sources of water, then apply a lasting fix.
Groundworks Editorial Team
