How to Seal Concrete Floor From Moisture

How to Seal Concrete Floor From Moisture


A concrete sealer is a protective barrier that gives longevity to concrete and makes cleaning easy. If your concrete is new, you’ll need to let it cure; wait at least one month before applying sealer. Before you apply it, check the weather. The sealer needs to be applied in dry conditions because it won’t adhere to damp concrete. The temperature also needs to stay above 50 degrees Fahrenheit during application and drying, taking up to three days.

Floor sealants are a very effective moisture mitigation solution for Royal Oak Michigan Basements. They’re used to seal the concrete subfloor and create an impermeable barrier between the subfloor and your flooring. The idea is that the sealant traps any moisture in the subfloor (either released by newly poured concrete as it cures or released into the concrete due to fluctuations in the water table). As such, it is unable to cause damage to your flooring or the building above.

If you select the right type of floor sealant, it will adequately mitigate the risk of moisture damaging your building and flooring. However, not all projects will require the use of floor sealants.

If your project requires concrete floor sealants, it’s important to understand the different types of products available. There are two main types of sealant:  water-proofing sealants and water vapor-proofing sealants.

While these may appear very similar at first glance, there’s an important difference: one blocks water vapor molecules, while the other only blocks the larger water molecules, meaning that water vapor can pass through the water-proofing sealant. This means the smaller water vapor molecules can pass right through the water-proofing sealer and become trapped beneath the floor covering’s non-permeable backing.

Once the water vapor molecule is trapped, it only takes a few degrees’ changes in temperature for this water vapor to condense into liquid water – and this is where the problems start. This trapped liquid water now has no place to go, as the treated slab will not allow the water to re-absorb, and the non-permeable backing will not allow it to evaporate. This means the water will begin to activate the slab’s pH and begin to break down the flooring adhesive and provide the perfect damp conditions conducive to mold and mildew growth. In contrast, a vapor-proofing sealant will trap both liquid water and water vapor molecules in the concrete, protecting your flooring and building from damage.

Combined with the right sealer, concrete can successfully withstand changing conditions, water damage, wear and tear associated with long-term use, abrasions, freeze-thaw cycles, and exposure to the elements. A penetrating sealer for your concrete will give it long-lasting protection by altering its chemical makeup, thereby reducing the need for reapplications. However, if the concrete has been paired with a surface sealer, it will need to be reapplied occasionally based on the type of sealer used. Epoxies, for example, have a longer life cycle than either acrylic or water-based sealers.

Unless you’ve applied a penetrating reactive sealer, you will eventually need to know how to remove old sealer from the concrete before a reapplication.  Before applying a new sealer, you must make sure the old one is completely gone. This is because any old sealer left on the surface of your concrete can impede the effectiveness of the newly applied sealant, preventing proper adhesion to the concrete surface.

The removal of old concrete sealer can be done in one of two ways: mechanical or chemical. The mechanical way involves using some tool to grind, sand, or blast away the sealer physically. This method can be noisy and damaging to the concrete. There can be significant scratching or damage sustained during the process of mechanically removing the sealer. The other method to remove sealer from a concrete floor or patio or remove concrete sealer of any type is chemical. You have a variety of choices when it comes to which products you want to use.

You may have heard that it is possible to use muriatic acid to etch your concrete surface. Unfortunately, muriatic acid is often used because it’s cheaper than professional-grade products. Using muriatic acid is not wise because it can actually damage the concrete surface and harm people, pets, and plants.  Using a professional-grade product that’s specially formulated for concrete sealer removal is considered to be best practice. 

Your product must prepare your concrete floors for whatever direction you plan to do after you’ve removed all the old sealer. If you’re working with a concrete sealer that’s merely a surface coat, at some point, you’ll need to strip it off totally before you reapply a fresh coat. Ensure that the product you use can penetrate deeply to remove all remnants of the old sealer completely. This is important because your new coat of sealer will need a fresh and clean surface to which it can adhere. Should you want to add any finish to your concrete, such as a decorative finish, you’ll need a product that allows for this. A penetrating sealer will make a concrete floor more resistant to damage from water and surface abrasions. Sealing a concrete floor will also make it harder, less dusty, and easier to maintain.

As long as it is properly sealed, concrete is non-porous, making it resistant to stains and easy to clean and maintain. Polished concrete floors are extremely durable. These are excellent in high foot traffic environments because of their superior scratch resistance. You should never attempt to clean your sealed or polished concrete floors with ammonia, bleach, citrus cleaners, pine-based cleaners, vinegar, or any highly acidic substance. These are not pH neutral and could break down or dull the sealant on your concrete flooring.

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