Transforming Exterior Cinder Block Walls With Paint

Painting a cinder block exterior foundation can be a great way to improve the look of your home and protect it from the elements. Here are the steps to paint a cinder block exterior foundation:

1. Clean the Cinder Blocks: Start by removing any old paint, dirt, grease, or mildew from the surface of the cinder blocks. You can use a pressure washer, scrub brush, or a combination of both. If there are any cracks or holes, fill them with polyurethane caulk.

2. Prime the Surface: Choose a bonding and filling primer that is latex acrylic-based. Apply the primer evenly with a nap roller and let it dry for at least 24 hours.

3. Paint the Cinder Blocks: Use a high-quality acrylic latex paint in your desired colour. Apply two coats of paint with a nap roller, allowing at least 12 hours of drying time between coats.

4. Consider the Weather: Avoid painting in extremely humid conditions or when there is a possibility of rain. Ideal painting conditions are warm temperatures (75-80°F or higher) and low to moderate humidity.

5. Sealant (Optional): If you want to add an extra layer of protection, consider using a concrete sealer or masonry waterproofer after the paint has dried.

Clean the cinder blocks

Cinder blocks are highly porous, meaning that they can easily attract and absorb dirt, dust, grease, oil, fingerprints, and hair. Here are some steps to clean your cinder blocks before painting:

Indoors

Protect the floor with a sheet of plastic. Mix trisodium phosphate (TSP) in a bucket with warm water, using about half a cup of TSP per two gallons of water. Use a nylon-bristled brush to scrub the cinder blocks, then rinse with clean water.

Exteriors

Clean outdoor cinder blocks with a pressure washer. Run a mild detergent through the pressure washer and let it soak on the blocks for about 15 minutes. Rinse the cinder blocks from the top down, staying about three to four feet away from the wall as cinder blocks are easily damaged.

To remove white efflorescence, try scrubbing with diluted vinegar.

Remove Old Paint

If the cinder blocks are coated with old paint, you will need to remove it. You can do this with a paint scraper, wire brush, or paint stripper. If there is caulk, silicone, or other materials on the cinder blocks, these will also need to be removed.

Let the Cinder Blocks Dry

Water soaks deeply into cinder blocks, so it is important to let them dry for at least 24 to 48 hours before painting. The blocks should be perfectly dry to avoid trapping moisture behind the paint.

Prime the cinder blocks

Priming the Cinder Blocks

Priming is a crucial step in painting cinder blocks. It creates a uniform base for the paint to adhere to and ensures that the final coat is free of pores. While primer is optional for other surfaces, it is a requirement for cinder blocks. Here's a step-by-step guide to priming your cinder block exterior foundation:

Step 1: Choose the Right Primer

Select a primer specifically designed for concrete and masonry bonding. Look for a latex acrylic-based bonding and filling primer that will fill in any cracks and pores in the blocks while also neutralizing the pH. If your cinder blocks are outdoors or in an area with water leakage issues, opt for a waterproof primer.

Step 2: Prepare the Surface

Before applying the primer, ensure that your cinder blocks are thoroughly clean and dry. Use a pressure washer or a garden hose with a scrub brush to remove any dirt, grease, or efflorescence (a white powder caused by water infiltration). Allow the blocks to dry completely, which may take up to 48 hours.

Step 3: Seal Cracks

Inspect your cinder blocks for any cracks and use polyurethane caulk to fill them. Cut the tip of the caulk tube and push the caulk into the crack, covering the joint completely. Smooth the caulk with a razor to create a seamless finish. This step will help create a uniform surface for the primer and paint.

Step 4: Apply the Primer

Use a nap roller to apply the primer to the cinder blocks. Choose the right roller nap length based on the surface texture: 0.5 inches for rough surfaces and 0.25 inches for smooth surfaces. Apply the primer using long, even strokes, ensuring complete coverage. One coat of primer is usually sufficient if you plan to paint over it. However, if you intend to leave the blocks primed without a topcoat, consider a second coat for added protection and durability.

Step 5: Allow Drying Time

After priming, let the cinder blocks dry thoroughly. This step is crucial, as applying paint over wet primer will affect the adhesion and overall finish. Check the manufacturer's instructions for the recommended drying time, typically around 24 hours. Ensure that the primer is completely dry to the touch before proceeding to the next step.

Tips for Priming:

• Measure the height and length of the wall to estimate the total area you'll be priming. This will help you purchase the appropriate amount of primer.
• For large areas, consider using a paint sprayer for a more efficient application. However, always back-roll to ensure even coverage and fill in any pores.
• If you're priming cinder blocks in a humid environment, you may need to allow extra time for the primer to dry thoroughly.

Choose the right paint

Cinder blocks are a common building material that can be used on the exterior of a home. Painting cinder blocks can be a great way to improve the exterior aesthetic of your home. The right paint will protect the foundation from weather damage and prevent future repair costs by sealing cracks and gaps.

The best types of paint for cinder blocks are acrylic latex paint and elastomeric paint. If you are looking for an option without any volatile organic compounds (VOCs), you can also use milk paint.

Be sure to buy exterior concrete paint if you are painting outdoor surfaces. Elastomeric paint is best for areas with high moisture, such as basements.

When choosing a paint, consider both the look and feel of the paint. Some paints are more durable than others, while some have a higher gloss finish. Ultimately, it is important to choose a paint that you are happy with and that will last for years to come.

Make sure the paint is designed for use on exterior vertical concrete surfaces. Many paints are only suitable for wood or metal surfaces, so using them on your foundation could result in peeling and flaking.

Select a product that will resist water under pressure from storm winds or ground pressure. Choose a paint that is fade-resistant to ensure that your home's exterior looks freshly painted for years.

It is also important that the paint is easy to apply. You don't want to spend hours struggling to apply it evenly, so look for a paint that goes on smoothly and evenly.

If you are painting in a sunny area, consider using a paint that is resistant to UV rays. This will help to protect your home from sun damage and keep it looking its best.

Finally, if you are concerned about mould or mildew, choose a paint that inhibits their growth. This will help to keep your home healthy and free from these unwanted organisms.

Apply the paint

Now that you have cleaned, dried, and primed the cinder block exterior foundation, it's time to paint! Here are the steps you need to follow:

• Choose the right paint: Select a high-quality acrylic latex paint that is specifically designed for exterior concrete surfaces. Make sure the paint can withstand the elements and protect your foundation from water damage. Consider factors such as durability, gloss finish, and colour when making your selection.
• Prepare your tools: Gather the necessary tools for painting, including a paint roller with a thick nap (long fibres) and a wide exterior paintbrush for edges and recesses. You may also need a paint tray and liners.
• Apply the first coat: Using long, even strokes, apply an even coat of paint to the cinder block exterior foundation. Work in vertical sections, covering as much area as possible with long strokes of the roller. Avoid overlapping sections, as they will take longer to dry and may create an uneven finish.
• Allow the first coat to dry: Keep the area well-ventilated and ensure the first coat of paint dries completely before proceeding. Depending on the humidity levels, this may take 12-18 hours. Touch the paint gently with a rag or gloved finger to check if it is dry; there should be no paint transfer.
• Apply the second coat: Once the first coat is completely dry, apply the second coat of paint using the same technique as the first. Work slowly and use a small amount of paint at a time to ensure an even application and prevent dripping.
• Let the second coat dry: Again, maintain good ventilation and allow the second coat to dry for at least 24 hours. Check if the paint is dry by touching it gently with a gloved hand or rag in an inconspicuous area. There should be no paint transfer.
• Apply additional coats (optional): If you desire a more even finish or better coverage, you can apply a third coat of paint. Be sure to wait at least 12 hours between coats.
• Clean up: Don't forget to clean your tools and properly dispose of any paint cans or leftover paint according to local regulations.

Allow the paint to dry

Allowing the paint to dry is a critical step in the painting process. Depending on the type of paint used, the drying time may vary, but it is generally recommended to let the paint dry for at least 12 hours before adding a second coat. In some cases, such as with oil-based paints, the drying time may be longer, up to 24 hours or more. It is important to ensure that the paint is completely dry to the touch before adding another coat, as this will ensure a smooth and even finish.

To speed up the drying process, it is recommended to keep the area well-ventilated, especially when painting indoors. Using fans can help accelerate the drying process. Additionally, maintaining proper temperature and humidity levels is crucial for optimal drying. Temperatures between 50 and 90° F are ideal for painting cinder blocks. High humidity can slow down the drying process, so it is advisable to choose a day with lower humidity when painting.

If you are painting in a humid environment, you may need to wait longer than 12 hours for the paint to dry completely. In some cases, you might need to wait up to 18 hours to ensure that the paint is thoroughly dry. It is essential to be patient and allow the paint sufficient time to dry to avoid any issues with the final finish.

Once the first coat is completely dry, you can proceed to apply the second coat of paint using the same technique as the first. Remember to work slowly and use a little paint at a time to ensure an even application and prevent dripping. After applying the second coat, allow it to dry for at least 24 hours before considering the project complete.

By following these instructions and allowing adequate drying time, you will achieve a professional-looking finish on your cinder block exterior foundation.

Frequently asked questions