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How To Waterproof An Old Basement​

Posted on January 19, 2025

Estimated Reading Time : 6 Min.

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How To Waterproof An Old Basement​

If you have a wet basement, you’re not just dealing with an inconvenience, you are dealing with an issue that can compromise your home’s structure and affect your family’s health. As a homeowner, knowing how to waterproof an old basement helps prevent expensive repairs and protect your home’s value, no matter the extent of the water issue. 

In this blog post, we’ll cover some proven methods to keep your basement dry and your home’s foundation strong.

Why You Should Waterproof Your Basement

Basement waterproofing

Before getting into waterproofing methods, it’s important to understand why it’s essential. Waterproofing protects your home from flooding, which can lead to major damage. It also prevents mold and mildew growth, which can harm your health and indoor air quality. 

Additionally, it helps maintain your home’s strength by stopping moisture buildup that can cause foundation cracks. By reducing humidity, waterproofing can also improve energy efficiency, making heating and cooling more effective. Ultimately, a waterproofed basement increases your home’s value and gives you more usable space by lowering the chance of flooding, pooling water, and excessive condensation.

Also Read: Best Basement Waterproofing Products Of 2025

Assessing Your Basement: Finding the Problem

To fix the problem, you first need to understand what’s causing the moisture—let’s break it down:

1. Conduct a Visual Inspection

Start by closely examining your basement for visible signs of damage or moisture. This will help you spot potential issues early on:

  • Cracks in Walls or Floors: Look for both small and large cracks. These can be entry points for water, jeopardizing the structural integrity of your basement.
  • Water Stains or Damp Spots: Discoloration on walls, ceilings, or floors could signal leaks or condensation.
  • Mold or Mildew Growth: The presence of mold often indicates persistent water intrusion or high humidity levels.
  • Efflorescence: White, powdery residue on walls suggests water seepage through masonry.
  • Rust on Metal Fixtures: Corrosion on pipes or other metal components typically points to excessive moisture.

2. Test for Moisture Sources

Once you’ve identified visible signs of moisture, it’s important to determine where it’s coming from. Simple tests can help pinpoint the source:

  • Aluminum Foil Test: Tape a piece of aluminum foil to the wall and leave it for 24 hours. If there’s moisture on the outside, it’s condensation. If there’s moisture behind the foil, water is infiltrating the basement through the walls.
  • Hygrometer Readings: Use a hygrometer to measure the humidity level in your basement. If it’s over 50%, you may need to consider dehumidification.

3. Evaluate Groundwater and Drainage Systems

Groundwater and drainage systems play a significant role in maintaining your basement’s dryness. Assess these factors to prevent moisture problems:

  • Grading Around the Foundation: Ensure the ground slopes away from your home. This helps to prevent water from pooling near the foundation and seeping in.
  • Gutters and Downspouts: Check that gutters are clear and downspouts are directing water at least 5 to 10 feet away from the foundation.
  • Standing Water: Puddles near your home’s exterior could indicate drainage problems that need to be addressed.

4. Structural Integrity Assessment

Finally, assess the structural integrity of your basement to identify potential risks related to ground movement and the stability of the foundation:

  • Foundation Stability: Look for signs of settlement, such as uneven floors or misaligned doors and windows.
  • Party Wall Considerations: If your property shares walls with neighbors, make sure these are not affected by any shifts or cracks caused by structural issues.

After determining where moisture is entering your basement, you can move on to waterproofing either the outside or inside walls. 

Also Read: How Much Does Basement Waterproofing Cost In 2025?

How To Waterproof An Old Basement Wall​

Now, let’s get into the best waterproofing methods to keep your basement dry and secure:

Exterior Waterproofing For An Old Basement​

Starting from the outside, here are key ways to stop water from seeping into your basement:

1. Regrading the Yard

Regrading the yard around your home ensures that the ground slopes away from the foundation, preventing water from pooling near the basement walls. This method reduces the risk of leaks and seepage by directing rainwater away, which minimizes hydrostatic pressure on the foundation.

2. Installing Gutter Downspout Extensions

In addition to regrading, extending downspouts 10 to 15 feet away from the foundation helps prevent water accumulation near basement walls. Proper downspout placement directs rainwater far enough from the foundation, stopping soil saturation and water infiltration.

3. Applying Waterproof Membranes

Next, applying waterproof membranes to the exterior walls of the foundation creates an additional barrier against moisture. These membranes, made from durable materials like polyurethane or rubberized asphalt, block water from entering through cracks or porous surfaces for long-term protection.

4. Repairing Foundation Cracks

Before applying any waterproofing material, it’s crucial to repair any cracks in the foundation. Cracks allow water to seep through, so sealing them with epoxy or polyurethane injections restores structural integrity and prevents leaks.

5. Window Well Drainage and Covers

Another vulnerable point in your basement is the windows. Installing window well covers prevents water from entering through basement windows, while proper drainage means that any accumulated water is redirected away from the foundation.

Interior Strategies for Waterproofing An Old Basement​

If water still finds its way in, these interior solutions will help keep your basement dry:

1. Applying Interior Sealants and Coatings

On interior walls and floors, applying sealants like epoxy or urethane helps block any moisture from entering through cracks. These coatings form a water-resistant barrier, ideal for preventing minor leaks and dampness.

2. Installing Interior French Drains

If water has already seeped into your basement, installing interior French drains along the perimeter of the floor can help. These drains collect any water that has made its way inside and direct it toward a sump pump system that manages groundwater that bypasses exterior waterproofing.

3. Sump Pump Installation

Sump pumps play a critical role in managing water inside the basement. Installed in a sump pit, the pump removes accumulated water, directing it safely away from your home’s foundation. Many modern sump pumps even include battery backups so they continue to function during power outages.

4. Vapor Barriers on Walls and Floors

Another way to keep moisture at bay is through vapor barriers. These semi-permeable sheets block moisture from rising through floors or seeping through walls, keeping the basement dry while still allowing vapor to escape.

5. Dehumidifiers for Humidity Control

Installing a dehumidifier helps reduce humidity levels in the basement, preventing condensation on surfaces like pipes and walls. This is especially helpful for older basements that tend to be more humid, preventing mold growth and musty odors.

6. Reinforced Wall Liners

Heavy-duty plastic wall liners channel any incoming water to a drainage system, ensuring it doesn’t reach the living space. These liners are most effective when combined with interior French drains, providing a comprehensive approach to moisture management.

7. Crack Injection Repairs (Epoxy/Polyurethane)

For visible cracks inside the basement, crack injection repairs seal them effectively with epoxy or polyurethane, restoring both structural strength and preventing water from entering through the gaps.

How To Maintain Your Waterproofed Basement

Once your basement is waterproofed, follow these tips to ensure it stays dry and problem-free.

1. Regular Inspection of Walls and Floors

Check for dampness, mold, or peeling paint regularly to catch problems early.

2. Check Gutters and Downspouts

Clean gutters twice a year to prevent water from pooling near the foundation.

3. Maintain Exterior Drainage Systems

Ensure exterior drains are clear to prevent water buildup around the foundation.

4. Test Sump Pump Functionality

Test the sump pump occasionally and replace it every 7 to 10 years.

5. Control Indoor Humidity Levels

Keep humidity under 50% with a dehumidifier and empty it regularly.

6. Inspect Window Wells and Covers

Check window wells for debris and make sure covers are properly installed.

7. Monitor Landscaping and Grading

Check that landscaping slopes away from the foundation to direct water runoff.

8. Address Cracks Promptly

Seal any cracks in the foundation to prevent water seepage.

9. Review Waterproofing Solutions Regularly

Reapply sealants and coatings as needed to maintain waterproofing.

Get Professional Basement Waterproofing Services From A. Fricker Roofing & Waterproofing

Waterproofing an old basement may seem overwhelming, but understanding the causes of leaks and choosing the right solutions can help create a dry, usable space. Whether you choose interior, exterior, or a mix of both methods, the important thing is to tackle the problem early on.
Dealing with a damp, leaky basement? Don’t let water damage affect your home’s foundation. At A. Fricker Roofing & Waterproofing, we offer expert basement waterproofing services to stop leaks with both interior and exterior waterproofing methods. With years of experience, we provide reliable, long-lasting results. Contact us today at (918) 402-7167!

How To Waterproof An Old Basement​