The truth is that a dehumidifier does nothing to counter or reverse the effects of efflorescence on your crawl space walls.
The reason high humidity can cause efflorescence, is because high humidity leads to condensation forming on the masonry surfaces. Condensation causes beads of moisture to form on the cool surfaces and is absorbed into the porous cement. Remedy For Excessive Humidity: Buy a good dehumidifier for your basement.
Preventing Efflorescence
Applying a hydrophobic sealant to a wall, floor, or ceiling will prevent the water from soaking into the building material.
Dehumidifiers work by removing moisture from the air. This can help to reduce condensation on walls and prevent mould and mildew growth. However, dehumidifiers will not necessarily dry out damp walls. If your walls are damp, you may need to use a combination of a dehumidifier and a fan to help dry them out.
A solution of baking soda (sodium bicarbonate) and water (Approx. 1 lb. Of baking soda per 5-gallons of water) can be used to neutralize the stain. The solution should be applied until it stops fizzing.
Vinegar and water solution—Efflorescence can be removed by using a dilute solution of household white vinegar and water. A vinegar and water solution is relatively inexpensive, non-toxic, and easy to obtain, mix and apply. Dilution ratio is 20–50% vinegar in water by volume.
A dehumidifier typically needs between 24 and 72 hours to completely dry out a room. It's critical to continue using the dehumidifier until the humidity levels are normal.
Using a variety of dehumidification methods (such as compressor or desiccant), these powerful machines can extract a surprising amount of moisture from your whole home. You'll be left with drier air, much less conducive to the growth of allergy-triggering dust mites and mould.
There is a chance of dehumidifying your home too much with a dehumidifier, especially if you are leaving your dehumidifier running for several hours on a timer unattended.
Using low alkali Portland cement can help reduce efflorescence. A well-graded aggregate, using a low water-to-concrete ratio, and preventing premature evaporation of water during curing are all good ways to reduce mineral salts. And finally, water sources used in construction should be clean, potable, and salt-free.
Efflorescence is removed by natural weathering processes - as rainwater is slightly acidic, it gradually dissolves and washes away the deposits. The process may also be assisted by warm dry weather when the deposit is blown away.
However, wall cracks, foundation cracks, pores in the concrete and even the floor-wall joint in your basement can create that entry point. When you see efflorescence, it means water is leaking into the area where you see it.
It is common for people to confuse mold with efflorescence. Efflorescence itself isn't dangerous or harmful. It can lead to potential moisture problems that can cause structural damage to building materials.
No-one can say how long any incidence of efflorescence will last. It might be a few weeks; it might be a couple or three months; it &could be a year or two. There are so many factors affecting its generation and appearance, and its disappearance that an educated guess is the best we can manage.
A few major differences between efflorescence and mold growth: Mold grows, efflorescence doesn't. Mold can grow on just about any surface, whereas efflorescence doesn't spread. Mold is a fungus, whereas efflorescence is moisture that evaporates into salt deposits.
No, your dehumidifier should not have to run constantly to regulate the air humidity. An optimal humidity level to shoot for is between 30 and 50 percent.
Most dehumidifiers should not be operated in temperatures below 60° F, since the moisture removed from the indoor air can freeze when it condenses on the cooling coils, which can damage the unit.
Dehumidifier Placement Guide
To ensure the humidity in the balanced, position it at least 12 inches from walls and other objects so air can circulate freely. Avoid placing the unit near window panes or any drafty area to prevent cold air from entering and affecting its performance.
A dehumidifier should collect around 10-20 pints a day. However, factors such as relative humidity levels, size of the appliance, location, and temperature can affect how much it collects.
Most dehumidifiers will remove between 30 and 70 pints of water per day.
For the worst-case situations, is it okay to have them running constantly? A dehumidifier can be run constantly but in most cases it shouldn't need to be. Running a dehumidifier constantly can cause your home to become too dry, leading to health and other property problems.
Efflorescence and alkali salts can be removed by dry brushing with a stiff bristled brush followed by wet sponging the surface with a mild 5% solution of white vinegar (acetic acid) in water. The whole area should then be wiped down with a damp cloth and allowed to dry thoroughly.
The acidity in the vinegar helps remove the efflorescence and calcium deposits by breaking down mineral crystals. After cleaning the surface, let dry for 48-72 hours (moisture content below 25%).
Here's the deal with efflorescence and sealing … you do NOT want to seal before your pavers have had the chance to “breathe” and go through their normal efflorescence cycle. By sealing too soon, you'll run the risk of trapping migrating salts beneath the coating of sealer.