Quck answer
Waterproofing concrete surfaces is essential to protect them from water damage. Here are some key steps to follow:
1. Clean the concrete surface thoroughly to remove any dirt, debris, or existing coatings.
2. Repair any cracks or damaged areas using a concrete patching compound.
3. Apply a concrete waterproofing sealer using a brush or roller. Make sure to cover the entire surface evenly.
4. Allow the sealer to dry completely before applying a second coat if necessary.
5. Consider adding a topcoat for additional protection and durability.
6. Regularly inspect the waterproofed surface and reapply the sealer as needed.
By following these steps, you can effectively waterproof your concrete surfaces and extend their lifespan.
If you have a concrete patio, garage, or driveway, it is important to seal the concrete to protect it from water damage. This should be done when the surface is first installed and periodically throughout its lifespan. Sealing the concrete creates a barrier that repels water while allowing trapped water vapors to escape. It also prevents stains from mold and mildew and increases the durability of the concrete by reducing corrosion, efflorescence, freeze-thaw damage, and spalling.
There are two types of concrete sealers available: film-forming sealers and penetrating sealers. Film-forming sealers create a protective layer of acrylic, epoxy, or urethane on the surface of the concrete. These sealers are easily found at home improvement stores and provide a wet or high-gloss finish. However, they require more frequent reapplication. Penetrating sealers, on the other hand, permeate the concrete and form a chemical barrier. These sealers often use substances such as silanes, siloxanes, silicates, and siliconates. They may be more expensive and require purchase from a specialty dealer, but they last longer and do not alter the appearance of the concrete.
Note: It is important to wait at least one month before applying sealer to new concrete to allow it to fully cure.
If your concrete surface has been previously coated, you may need to remove the coating before applying new sealant. Follow the instructions provided by the sealer manufacturer in this case. Even if you do not need to remove the coating, you will still need to prepare the surface. Refer to the instructions provided by the waterproofer for proper preparation. Additionally, if you plan to paint the surface after waterproofing, make sure that the waterproofer is compatible with painted finishes.
Tip
Check the weather forecast before applying the sealer. The concrete must be dry, so avoid applying the sealer in damp conditions. The temperature should be between 50 and 90°F on the day of application and for the following two days for the sealer to cure properly. It is also best to avoid applying the waterproofer in direct sunlight.
What You Will Need
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Push broom
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Safety equipment: goggles and acid-resistant gloves and boots
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Cleaner/etcher for concrete
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Large plastic watering can
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Long-handled non-metal scrub brush
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Water hose
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Plastic squeegee with a long handle (optional)
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Liquid waterproofer for concrete
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Large painter’s tray
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Paintbrush
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Wide roller with a 1/4-inch nap
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Long handle for the roller
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Mop
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Floor-cleaning detergent
Warning
When using cleaner/etcher, always wear safety equipment such as goggles and acid-resistant gloves and boots. If working in an enclosed space like a garage, ensure proper ventilation.
Step 1: Clean and Prepare the Concrete Surface
These necessary steps are crucial for preparing the concrete to accept the waterproofer. Do not skip them!
- To protect your walls, cover them with a plastic sheet. Use a push broom to sweep the concrete thoroughly and remove any dirt and debris. Repeat the sweeping process to ensure all dust is removed.
- Make sure the concrete is completely dry. Pour the cleaner/etcher into a large watering can and sprinkle it on the surface. Leave it on for 10 to 20 minutes.
- Scrub the surface vigorously with a long-handled scrub brush. If the cleaner/etcher starts to dry, lightly mist it with water to keep it wet.
- After scrubbing, rinse the surface thoroughly with a hose. Make sure the rinse water does not go down storm drains.
- If desired, use a squeegee to remove water from the concrete. Let the surface dry completely, preferably overnight (24 hours is best).
Once properly prepared, the surface should feel like medium-grit sandpaper. For stained or smooth, dense concrete, you may need to apply cleaner/etcher more than once. After drying, there should be no residue or loose concrete. Lightly run your finger on the surface, and if it comes away with dust, rinse again.
Step 2: Apply Waterproofer/Sealer to the Concrete Surface
Depending on the porosity of your concrete, a gallon of waterproofer can cover 250 square feet.
- Pour waterproofer into a large painter’s tray. If sealing an indoor area, use a paintbrush to apply sealant to the floor along the walls’ edges. This will prevent touching the walls with the roller in the next step.
- Load the roller with sealant from the painter’s tray. Roll it onto the concrete, saturating the surface completely. If sealer puddles, spread it to drier areas.
- Allow the first coat of sealer to dry.
- If a second coat is needed, apply it in the opposite direction from the first coat to ensure even coverage.
- Let the sealer dry and cure. Most sealers require 24 to 48 hours to cure.
Step 3: Concrete Surface Aftercare
Check the product for specific drying instructions, but generally, wait at least three days before allowing heavy foot traffic on the sealed surface and 14 days before driving on it. Wait 30 days before cleaning with a mild floor-cleaning detergent and mop.
Areas with heavy traffic may need annual touch-ups. Resealing may be necessary depending on the sealer used and the surface’s wear and tear. Signs that it’s time to reseal include water soaking into the concrete instead of beading on the surface, and the concrete appearing scratched, dull, or dirty. Acrylic waterproofer lasts one to three years, while epoxies, polyurethanes, and polyaspartics can go five to 10 years between applications. Penetrating sealers may never require reapplication.
Sealed concrete on the left, unsealed on the right.
Image Credit:
Walkers Concrete LLC
