How to Waterproof a Block Foundation From Exterior: Essential Techniques and Tips

How to Waterproof a Block Foundation From Exterior?

To waterproof a block foundation from the exterior, there are several steps that can be followed.

First, the surface should be properly prepared by removing any dust, dirt, or debris.

Next, voids, joints, and cracks on the surface should be reinforced with hydraulic cement or masonry caulk.

Before starting the waterproofing process, it is important to assess the water table and select an appropriate waterproofing membrane.

Fluid-applied asphaltic rubber membranes are recommended for sealing below-grade concrete block walls.

These membranes should be applied with a brush, roller, or trowel and allowed to fully cure for 24 hours.

To complete the waterproofing system, exterior drainage boards and footing drains should be installed.

Once the waterproofing membrane is fully cured, the foundation can be backfilled.

Overall, proper preparation, the right choice of waterproofing membrane, and the installation of drainage systems are essential for effectively waterproofing a block foundation from the exterior.

Key Points:

  • Prepare the surface by removing dust, dirt, and debris.
  • Reinforce voids, joints, and cracks with hydraulic cement or masonry caulk.
  • Assess the water table and select an appropriate waterproofing membrane.
  • Use fluid-applied asphaltic rubber membranes for sealing below-grade concrete block walls.
  • Apply the membrane with a brush, roller, or trowel and allow it to cure for 24 hours.
  • Install exterior drainage boards and footing drains to complete the waterproofing system.
  • Backfill the foundation once the waterproofing membrane is fully cured.
  • Proper preparation, choice of membrane, and installation of drainage systems are essential for effective waterproofing.

Did You Know?

1. Did you know that the world’s first waterproofing material was made from a mixture of boiled animal fats and tar, dating back to ancient Mesopotamia? This early form of waterproofing was used to protect and seal the foundations of buildings.

2. In the early 20th century, one of the most effective waterproofing methods for block foundations was the use of asphalt coatings. It was discovered that applying a thick layer of asphalt paint to the exterior of a block foundation could effectively prevent water infiltration.

3. While there are many modern waterproofing methods available today, a unique technique employed in some parts of the world involves using a combination of specialized waterproofing cement and layers of recycled rubber tires. This not only provides effective protection against water damage but also helps with insulation.

4. Before waterproofing became a common practice, many ancient structures were designed to adapt to water-related challenges. For example, some Roman buildings featured raised foundation walls with ventilation gaps, allowing any water that seeped in to evaporate naturally.

5. Have you ever wondered why block foundations tend to crack over time, leading to water seepage? One lesser-known cause is expansive clay soil, which can expand and contract with changes in moisture levels. This constant movement puts pressure on the foundation walls, resulting in cracks and potential water infiltration. Waterproofing helps mitigate such issues by preventing water from exacerbating the problem.

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Importance Of Waterproofing Concrete Block Foundations

Waterproofing a concrete block foundation from the exterior is essential for ensuring its long-term performance. Concrete block foundations are susceptible to water leaks due to their porous nature and numerous joints.

Moisture intrusion can damage the foundation and result in leaks into the occupied space. The mortar joints in the foundation can crack over time, providing a pathway for moisture to seep through. Therefore, implementing waterproofing measures is crucial to prevent moisture intrusion and protect the foundation.

Common Issues With Concrete Block Foundations

Concrete block foundations face several common issues that make them vulnerable to water intrusion.

  • Concrete blocks are more permeable to water and water vapor compared to poured concrete, making them susceptible to moisture-related damage.
  • The pores of concrete blocks can enlarge due to moisture, leading to structural damage.
  • Concrete blocks have more joints and areas to seal compared to poured concrete, making them more prone to leaks.
  • Mortar joints on all sides of the blocks can develop cracks over time, providing pathways for water infiltration.

These issues highlight the importance of implementing effective waterproofing strategies for concrete block foundations.

Recommended Membranes For Waterproofing

When it comes to waterproofing concrete block foundations, there are two recommended types of membranes:

  • Liquid rubber membranes: These are highly blended emulsified asphalt mixed with polymers for enhanced durability. They are cold-process, fluid-applied, and easily adhere to surfaces. Liquid rubber membranes possess good vibration absorption, shear strength, and peel strength.
  • Self-adhering membranes: These membranes come in rolls and have a controlled thickness, which reduces the project timeline.

Both types of membranes are effective in preventing moisture intrusion and protecting concrete block foundations.

Steps For Waterproofing A Block Foundation

Here are the recommended steps for waterproofing a block foundation from the exterior:

  1. Prepare the surface: Remove any dust, dirt, or debris from the foundation. Ensure that the surface is dry, free of frost, and relatively smooth before proceeding.
  2. Reinforce voids, joints, and cracks: Before starting the waterproofing process, fill and smooth any voids, joints, and cracks on the surface of the concrete blocks using hydraulic cement or masonry caulk. Allow 24 hours for the filler to dry before proceeding with waterproofing.
  3. Assess the water table: Evaluate the water table and fluctuations throughout the year. This information will help determine the most suitable waterproofing membrane and system for the specific situation.
  4. Apply primer/adhesive (for sheet-applied membrane): If a sheet-applied membrane is chosen, apply a primer/adhesive to prepare the concrete block foundation for proper adherence of the membrane. This step ensures optimal waterproofing performance.
  5. Apply fluid-applied membrane: For sealing below-grade concrete block walls, fluid-applied asphaltic rubber membranes are recommended, especially when the water table is not a concern. Apply the membrane using a brush, roller, or trowel. Allow the membrane to fully cure for 24 hours before proceeding.
  6. Install exterior drainage boards and footing drains: To extend the life of the waterproofed concrete block wall, install exterior drainage boards and footing drains as part of a complete waterproofing system. These components redirect water and prevent damage to the foundation.
  7. Install dimple membrane drainage system: Once the waterproofing membrane system is fully cured, install a prefabricated dimple membrane drainage system over the membrane. This additional layer helps further protect against moisture penetration.
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Installing Drainage Systems And Exterior Drain Channels

In addition to waterproofing the concrete block foundation, it is essential to install exterior drainage systems and drain channels to ensure effective water management.

These systems help divert water away from below-grade walls and prevent water accumulation. Exterior drain channels, along with proper slope and grading, ensure that water flows away from the foundation and does not contribute to moisture-related issues.

By installing drainage systems and exterior drain channels, you can enhance the effectiveness of the waterproofing measures and provide additional protection to the foundation.

Considerations For Sealing Concrete Block Walls

When sealing concrete block walls, there are several considerations to keep in mind.

Before sealing, it is important to remove any painted walls and efflorescence for optimal adhesion of the waterproofing materials.

It is also crucial to choose products that have been tested together as part of a system to ensure compatibility and effectiveness.

Additionally, if the plan is to finish the blocks with stucco, it is recommended not to seal the walls first, as it may impair the stucco’s ability to stick.

By considering these factors, you can ensure the success of your concrete block wall sealing efforts and enhance the overall waterproofing performance.

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Frequently Asked Questions

How do you waterproof a block wall from the outside?

One effective method to waterproof a block wall from the outside is to apply a coating directly on the bare wall. This coating acts as a protective barrier, preventing water from seeping through. Another approach is to use a breathable or permeable barrier, which allows moisture to escape while still keeping water out. Additionally, a weather-resistant elastomeric layer can be applied to further enhance the waterproofing capabilities of the wall. It is also crucial to repair any cracks and fill voids before waterproofing, as these can provide entry points for water. Finally, installing an air and moisture barrier can provide an extra layer of protection against water infiltration.

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What is the best waterproofing for block foundation?

When it comes to waterproofing block foundations, a combination of RadonSeal Plus and Ion-Bond Armor has emerged as the most effective solution. This tag team of concrete sealers has provided countless homeowners with a foolproof method to address damp basements. With the application of these two products, the block walls are fortified against water intrusion, offering a reliable and long-lasting waterproofing solution for your foundation.

What is the best waterproofing for exterior foundation?

When it comes to waterproofing exterior foundations, one of the best options is the Poly Wall® Waterproofing Barrier Systems. These systems are specifically designed for new foundation walls and offer excellent protection against moisture-related issues. By applying these barriers below-grade, especially in areas where there is earth on one side and usable space on the other, such as crawl spaces, homeowners can greatly reduce the likelihood of water damage to their homes. With Poly Wall® Waterproofing Barrier Systems in place, you can be confident that your foundation is well-protected.

What should be done to the outside of a block foundation wall?

To properly protect a block foundation wall from water penetration and potential damage, it is crucial to apply a waterproofing membrane on the exterior surface. This membrane acts as a protective barrier, preventing water from seeping into the concrete blocks and causing structural issues. Additionally, proper drainage systems should be installed around the foundation to redirect water away from the wall, further safeguarding it against moisture infiltration. Regular inspection and maintenance of these measures are essential to ensure the long-term durability and stability of the foundation.

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