What To Use To Control Moisture & Humidity In Your Basement

Generally speaking, homeowners now recognize the importance of creating a vapor barrier on their walls. Whether through waterproof paint, a plastic vapor barrier, a penetrating concrete sealer, or some other method, creating this barrier will prevent water vapor from seeping through the pores of concrete.

In a finished basement, a vapor barrier will protect drywall and insulation from the moisture buildup that would otherwise lead to mold, mildew, and humidity passing through the concrete walls and floors located within the space. In an unfinished basement or cellar, sealing the walls and floor will create a drier environment, protecting stored items from rot and mold, and helping to control that musty smell that’s notoriously present in below-grade spaces.

However, there are a lot of basements out there – and a lot of companies competing to earn your consumer dollar on products that will help to control that moisture intrusion. And, like all things in the home improvement industry, some work better than others.

Let’s take a look at the three most common methods of moisture control:

1. Waterproof Paint

Most popular among do-it-yourselfers, many homeowners will opt for waterproof coatings and paints that are available at most local box stores. These products sport big promises, low cost, and seductive warranties that make them look like they’re a foolproof choice for any basement.

Unfortunately, these products have three major weaknesses:

• A Non-Penetrating Formula: These paints and coatings are surface-level only, and have a comparatively weak bond on your concrete surfaces. If this coating is used on surfaces that are dirty, the will peel off. They are also a weak choice for high-traffic areas of floor, where the surface coating can peel off.
• Poor Resistance To High Alkalinity Levels: There’s a lot of chemistry going on in the concrete walls of a basement – and the moisture that passes through may be highly alkaline. This is particularly true if your basement walls are new, and haven’t completed the years-long curing process. This alkalinity can break the bonds of surface coatings, causing them to blister and peel off.
• Vulnerability To Efflorescence Buildup: Along with moisture, minerals also pass through your basement walls. As the moisture evaporates or recedes, it can leave these minerals in the form of a white, powdery mineral salt known as efflorescence. As this builds up, it can also compromise the bond of paints and coatings. Read your warranty carefully, and you’ll see that it probably doesn’t cover walls with efflorescence!

To make matters worse, once these coatings fail, they can be extremely troublesome to remove. You’ll be working quite hard on those ugly, blistering, peeling walls – and most likely, you’ll be renting some equipment as well!

2. Plastic Vapor Barriers

Whether rigid or pliable, plastic vapor barriers are a good choice for preventing moisture that comes through basement walls. Because they attach mechanically to the walls, there is no concern of peeling or detaching from the walls as there is with waterproof paint. Additionally, this is the only solution that can also intercept water flooding through cracks in the concrete – ones that would otherwise bypass sealers and paint coatings. This flooding water would be directed to a perimeter drain system, presuming you have one in place. Typically, the seal is made permanent with epoxy or caulk along the top and seams.

Plastic vapor barriers install fairly quickly, and there’s no VOC’s or drying time to worry about. They can give a basement a brighter, more cheerful appearance, or they can be used behind finished walls.

There are three disadvantages to plastic vapor barriers

• Cost: The cost to buy, cut, and attach plastic vapor barriers can be much higher than simply applying a concrete sealer or waterproof paint.
• Mold Concerns: What happens to the moisture that collects behind this plastic vapor barrier? Many homeowners voice concerns of mold and mildew growth, although there is little scientific evidence to support a health issue of mold behind a sealed vapor barrier.
• Not Ideal For Floors: While this is a great option for the walls, it’s a less-than-impressive option for the floors. On a very flat floor, plastic floor tiles (without chipboard present) can be a possible vapor barrier substitute, but these tend to click and make noise on less even surfaces.

Despite the disadvantages, these vapor barriers provide a permanent solution, where applicable, and could be considered for moisture control in many homes.

3. Concrete Sealers

For the purpose of this article, we’ll discuss sliane-based concrete sealers. These sealers penetrate deep into the pores of the concrete, activating with the minerals in the concrete to create a glasslike barrier deep within the concrete. They’re safe to use indoors, and contain little or no VOC’s (brand depending).

Sliane-based concrete sealers activate quickly, and can be applied to both cured and newly-placed concrete. They will not change the appearance of the concrete, efflorescence and acidity will not harm them, and they’re able to be painted over with ease. Installation is fast (done with a brush, roller, or sprayer), and they’re middle-of-the-road in overall cost.

Three disadvantages to consider are as follows:

• Provides Moisture Control ONLY: Unlike plastic vapor barriers, this will not be able to breach cracks or stop flooding water. It’s meant only as a sealer for water vapor that would otherwise pass through the pores of the concrete.
• Take Care When Installing: Sliane-based sealers cause etching on glass, should they come in contact with it. When installing, be sure to protect and/or avoid glass surfaces.
• Possible to Overapply: Waterproof paints can be coated thickly, thinly, or in multiple layers, and it’s impossible to overapply a plastic barrier. But an installer should be careful to only use enough sliane-based sealer to damp the concrete, as too much will leave a white residue behind.

Sliane-based sealers are the ideal choice for basements that are damp but do not flood, as they are inexpensive, install quickly and subtly, and provide a lasting solution.