Waterproofing | How To Waterproof A Block Foundation From Exterior

Aug 24

Protecting your home's foundation from water damage is crucial to ensure its longevity and structural integrity. Block foundations are commonly found in many homes among the various types of foundations. Waterproofing a block foundation from the exterior can be challenging yet essential to prevent water infiltration and potential structural issues. In this blog, we will explore the steps and techniques on how to waterproof a block foundation from exterior, safeguarding your home from the damaging effects of water.

Importance of waterproofing block foundations

Block foundations, commonly made of concrete or cinder blocks, are susceptible to water intrusion due to their porous nature. When water seeps into the foundation, it can cause a range of problems, such as mold growth, deterioration of the blocks, and even compromising the structural integrity of the building. Waterproofing your block foundation is essential to prevent these issues and safeguard your investment.

Why Waterproof Your Block Foundation Wall?

Keeping your home's foundation dry is essential to avoid potential moisture-related issues. However, traditional foundation vents lack motors and often struggle to handle excess moisture in unfavorable conditions. This is particularly problematic when block foundation walls allow water into the crawl space.

Block foundation walls are naturally porous, designed to absorb moisture from the mortar. Unfortunately, this also means they can absorb groundwater, which can then reach the framing of your home. It's crucial to waterproof the block foundation and install a vapor barrier to prevent such water absorption. In some cases, adding a French drain can be beneficial. These measures prevent exterior moisture from entering your crawl space or basement through the block walls.

What is Block Foundation Waterproofing

Foundation waterproofing creates a barrier between the foundation and groundwater to prevent water from entering the structure. When it comes to blocking foundations, this process is typically done from the exterior, as it provides a more comprehensive and long-lasting solution compared to interior waterproofing methods.

Causes of water intrusion in block foundations

Before moving forward with waterproofing, it's crucial to understand the primary causes of water intrusion. Some common reasons include:

Poor drainage: Inadequate grading around the foundation can lead to water pooling against the walls, increasing the chances of seepage.
Hydrostatic pressure: Water-saturated soil surrounding the foundation can exert pressure on the walls, forcing water to penetrate through cracks and gaps.
Cracks and gaps: As block foundations age, they can develop cracks and gaps, providing an entry point for water.
Absence of proper waterproofing: Some older buildings may need proper waterproofing measures, making them vulnerable to water damage.

Identifying signs of water damage

Before you start the waterproofing process, it's essential to inspect your block foundation for signs of water damage. Look out for the following indicators:

Damp or musty odors in the basement or crawl space.
Efflorescence: White, chalky substance on the walls, indicating salt deposits left behind by evaporating water.
Cracks in the walls, especially if they are leaking or show signs of water penetration.
Mold or mildew growth on walls or surfaces.
Staining or discoloration on the walls.

How exterior waterproofing works

Exterior waterproofing of a block foundation typically involves the following steps:

Excavation: The area around the foundation is excavated to expose the exterior walls completely.
Cleaning and repairing: The walls are cleaned of any dirt, debris, or loose material. Cracks and gaps are repaired to ensure a smooth surface.
Application of waterproofing materials: A waterproofing membrane or coating is applied to the exterior walls. This barrier prevents water from seeping into the foundation, allowing any trapped moisture to escape.
Drainage system: A drainage system, such as perforated pipes or a French drain, redirects water away from the foundation.
Backfilling: Once the waterproofing is in place, the excavated area is backfilled with gravel or soil, ensuring proper drainage from the foundation.

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Exterior Block Foundation Waterproofing Methods

Excavation and Drainage

The first step in waterproofing a block foundation from the exterior is to excavate the area around the foundation. This allows access to the foundation walls and footing, making identifying any cracks, defects, or weak points easier. Proper drainage is also crucial for redirecting water away from the foundation. Install a perforated pipe, a weeping tile, alongside the footing to collect and direct groundwater away from the foundation.

Waterproofing Membranes

Waterproofing membranes are an effective barrier against moisture and are commonly used in exterior foundation waterproofing. These membranes are typically made from asphalt-modified polyurethane, rubberized asphalt, or other synthetic materials. The membrane is applied to the foundation walls, creating a seamless and impenetrable barrier that prevents water from seeping into the block walls.

Exterior Sealants and Coatings

Exterior sealants and coatings are complementary methods used in conjunction with waterproofing membranes. These products add an extra layer of protection against water intrusion and can also provide resistance to environmental factors such as UV rays and soil erosion. Acrylic-based sealants and coatings are commonly used for their durability and flexibility.

Step-by-Step Waterproofing Process

Start with a Clean Surface: Before implementing any waterproofing method, clean the exterior surface of the block foundation to ensure optimal adhesion.
Address Existing Cracks: Seal any visible cracks in the blocks with an appropriate sealant to prevent water from entering through these openings.
Choose the Waterproofing Method: Depending on the level of water exposure and your budget, select the most suitable method - excavation and drainage, waterproofing membranes, or exterior sealants and coatings.
Prepare for Excavation (if applicable): If you opt for excavation and drainage, ensure the trench is dug to the appropriate depth and with a proper slope.
Apply the Chosen Method: Carefully follow the manufacturer's instructions to apply the selected waterproofing method, whether it's a membrane, sealant, or coating.
Inspect and Monitor: Regularly inspect the foundation for any signs of water infiltration or damage. Promptly address any issues that may arise to avoid more extensive problems.

Professional vs. DIY Waterproofing

Pros:

Cost Savings: DIY waterproofing can be more budget-friendly, as you won't incur labor costs.
Hands-on Experience: It can be a rewarding experience to work on your home's foundation yourself.

Cons:

Expertise and Knowledge: Waterproofing requires specialized knowledge and skills to be effective. DIYers may not be aware of the best methods and materials to use.
Time-Consuming: Waterproofing a foundation is time-consuming, and mistakes may lead to costly repairs down the road.
Limited Warranties: Professional waterproofing companies often offer warranties, providing additional peace of mind.

How Do I Waterproof My Block Foundation From the Outside?

Assess the Foundation

Before you begin waterproofing your block foundation, it's essential to inspect it thoroughly. Look for any visible cracks, gaps, or damaged mortar joints that could serve as potential entry points for water. Take note of problem areas, as addressing them during the waterproofing process will enhance the effectiveness of your efforts.

Clean and Prepare the Surface

A clean and well-prepared surface is essential for proper adhesion of waterproofing materials. Use a wire brush or power washer to remove dirt, debris, and loose mortar from the foundation's surface. Make sure the area is completely dry before proceeding to the next step.

Repair Cracks and Mortar Joints

Patch up any visible cracks or gaps in the foundation using hydraulic cement or an appropriate concrete patching compound. Pay close attention to corners and intersections, as these areas are particularly vulnerable to water intrusion. Addressing these issues will prevent water from seeping into the foundation later on.

Apply Waterproofing Membrane

Waterproofing membranes are an integral part of the exterior foundation waterproofing process. Choose a high-quality, rubberized asphalt membrane designed explicitly for below-grade applications. Roll or brush the membrane onto the prepared surface, ensuring complete coverage.

Install Drainage System

An effective drainage system is critical for diverting water away from your foundation. Consider installing perforated drain pipes, also known as weeping tiles, along the exterior perimeter of your foundation. These pipes should be placed in a gravel bed and sloped to direct water away from the foundation towards a proper drainage outlet.

Backfill Properly

Once the waterproofing membrane and drainage system are in place, carefully backfill the excavated area around the foundation. Use clean, fill dirt, and avoid using sharp rocks or debris that could damage the waterproofing layer. Ensure the soil slopes away from the foundation to promote water runoff further.

Maintain Landscaping

After waterproofing, it's essential to maintain the landscaping around your home. Trim bushes, trees, and shrubs away from the foundation to prevent them from rubbing against the waterproofing membrane or causing damage to the drainage system. Keep gutters and downspouts clean and debris-free to ensure proper water flow from the house.

Waterproofing a block foundation from the exterior is vital to saving your home from severe water-related problems in the long run. By understanding the causes of water infiltration and implementing proper waterproofing techniques, you can protect your foundation and, in turn, your entire home. Regular maintenance and proactive measures will contribute to a dry and secure living space, providing peace of mind and a solid foundation for many years. Remember, investing in waterproofing today can save you from extensive repairs tomorrow. So, take the time and effort to safeguard your home's foundation—it's well worth it!

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