Keeping your basement dry helps prevent water damage, mold growth, and serious foundation problems. If you notice musty odors, condensation, discolored drywall, or puddles in your basement, it’s time to waterproof the space. While some methods involve waterproofing from the interior basement walls and floors, you may need to waterproof your basement from the outside to address more severe moisture problems.

In this guide, we’ll explain how different basement waterproofing methods work, highlight why waterproofing is important, and provide step-by-step instructions for exterior waterproofing.

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What Causes Basement Water Problems?

Before exploring waterproofing solutions, you should understand why basements are prone to water issues and the risks associated with moisture problems.

Common Causes of Basement Moisture

Several factors can contribute to basement water problems, including the following:

• Foundation cracks: Small fissures in your foundation walls can allow water to seep through.
• High water table: Water can penetrate even through solid concrete in areas with elevated groundwater levels.
• Hydrostatic pressure: When soil becomes saturated with water, it pushes against basement walls and floors.
• Plumbing leaks: Faulty pipes or connections can introduce moisture into your basement.
• Poor drainage: Improper grading or clogged gutters can direct water toward your foundation.

Risks and Consequences of Water Damage

If ignored, basement water issues can escalate, leading to the following:

• Decreased property value: Water damage often decreases home resale value.
• Mold and mildew growth: Damp environments can proliferate harmful fungi.
• Pest infestations: Moisture-rich environments are inviting to insects and rodents. If this is already a concern, you might need to hire a pest control expert.
• Reduced air quality: Moisture can carry allergens and other irritants into your home’s air.
• Structural damage: Prolonged exposure to moisture can compromise your home’s foundation.

Check out the video below for more information about different basement dampness sources and how to address them. Plumbing expert Richard Trethewey explores wet basement solutions that direct water away from your foundation, provide a vapor barrier, and control your basement’s humidity.

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Benefits of Exterior Basement Waterproofing

Waterproofing your basement from the outside provides numerous benefits, including the following:

• Avoid expensive repairs: Basement waterproofing prevents water damage, potentially saving you from costly foundation repair expenses.
• Energy efficiency: Proper waterproofing enhances your home’s insulation capabilities.
• Health benefits: Keeping moisture at bay helps prevent mold-related health issues.
• Increased living space: You can convert a dry basement into a functional area.
• Long-term protection: Exterior methods tackle water infiltration’s root causes.
• Peace of mind: You’ll worry less about water damage during extreme weather conditions.

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Types of Basement Waterproofing

Basement waterproofing solutions fall into two main types—interior and exterior. We’ll explore both below.

Interior Basement Waterproofing

Interior basement waterproofing combines several techniques to stop water from entering the space. Here’s an overview of the process:

1. Repair small cracks in concrete or cinder block walls with hydraulic cement or sealant.
2. Fill gaps around doors, windows, ducts, and pipes with polyurethane sealer.
3. Finish sealing your basement walls with several layers of waterproof paint.
4. To address more severe water seepage problems, install a waterproof membrane called a vapor barrier between the concrete and any finishing materials.
5. Hire a waterproofing contractor to install an interior drainage system to address pooling water. This drainage system might include a French drain system—which consists of drain tiles surrounded by gravel into which water can flow—or a sump pump that moves water away from your foundation. 

Exterior Basement Waterproofing

Exterior waterproofing is more expensive and disruptive but is the most effective option. Consider the following exterior waterproofing techniques:

• Improve drainage by upgrading gutters and extending downspouts to direct runoff away from your house.
• Install French drains to create an escape route for excess water.
• Install window well drains or covers to prevent water from leaking into basement windows.
• Regrade your yard so water runs away from the foundation.

If groundwater is a problem, you may need to expose the exterior foundation and apply a cementitious coating or waterproofing membrane to the foundation walls. This rubberized asphalt membrane keeps all water out and is often the most effective solution. However, it’s also the most expensive option because you’ll need to excavate and backfill the area around the foundation.

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Types of Exterior Waterproofing Methods

There are several methods to accomplish exterior basement waterproofing. Each caters to specific circumstances and budget considerations.

Excavation and Membrane Application

This method involves excavating around your foundation to apply a waterproof membrane. Follow these steps:

1. Excavate the soil around the foundation walls.
2. Clean and repair the exterior wall surface.
3. Apply a waterproof membrane or coating.
4. Install a drainage board for added protection.
5. Backfill with gravel and soil.

French Drain Installation

Install a French drain system as follows to divert water away from your foundation:

1. Dig a trench around your home’s perimeter.
2. Place a perforated pipe surrounded by gravel in the trench.
3. Verify the pipe is sloped to direct water away from the foundation.
4. Cover the setup with soil and adjust grading as necessary.

Grading and Landscaping Solutions

Make simple landscaping changes, such as the following, to reduce moisture problems:

1. Make sure the ground slopes away from your foundation.
2. Install gutters and downspouts to channel water 5 feet away from your home.
3. Create a swale or dry creek bed to guide water away naturally.
4. Use deep-rooted plants to help absorb excess water.

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Step-by-Step Guide to Exterior Basement Waterproofing

Follow our step-by-step guide below to undertake a thorough exterior waterproofing project.

Assessing Your Basement’s Needs

1. Look for visible cracks, damp spots, or mold.
2. Evaluate the grading around your home.
3. Inspect your current drainage system.
4. Consider seeking a professional assessment for a thorough evaluation.

Preparing the Work Area

1. Contact 811 to mark utility lines before you begin excavation.
2. Clear away obstacles such as shrubs or outdoor installations.
3. Set up safety barriers around the project site.
4. If needed, rent equipment like an excavator.

Applying Waterproofing Materials

1. Clean and repair the foundation wall surface.
2. Apply primer if the waterproofing product requires it.
3. Install the waterproof membrane per manufacturer guidelines.
4. Allow sufficient drying time before proceeding.

Installing Drainage Systems

1. Lay a drainage board against the waterproofed wall.
2. Place a perforated drain pipe at the foundation’s base.
3. Surround the pipe with gravel to facilitate water flow.
4. Connect the system to a sump pump or a daylight drainage point.

Backfilling and Finishing

1. Cautiously backfill the excavation area with gravel and soil.
2. Compact the soil to avoid settling.
3. Grade the soil so it slopes away from the foundation.
4. Replant grass or landscaping to restore the area if desired.

Check out the video below to explore more basement waterproofing tips from general contractor Tom Silva:

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Professional vs. DIY Basement Waterproofing

You can DIY some waterproofing tasks, but we recommend leaving more extensive or complex methods to the professionals.

When To Call a Professional

Consider hiring a professional in the following cases:

• For extensive foundation damage
• If you’re uncertain about the most suitable waterproofing technique
• If you lack the necessary skills or equipment
• When permits are mandatory

DIY-Friendly Waterproofing Tasks

You can perform the following waterproofing tasks yourself with the right tools and knowledge:

• Applying waterproof coatings on small areas
• Extending or installing downspouts
• Improving grading and landscaping
• Repairing minor cracks

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How To Hire a Basement Waterproofing Pro

Consider the following tips when hiring a professional contractor for exterior basement waterproofing:

• Ask family and friends for references. If they don’t have someone to recommend, check reputable customer review sites such as Trustpilot.
• Check the Better Business Bureau’s website for waterproofing contractors in your area. These listings will include the BBB’s rating, the company’s accreditation status, and important information about time in business and customer complaints.
• Get quotes from at least three local contractors before making your choice. While cost shouldn’t be the only factor you consider, this will help you determine the price range in your area.
• Verify that workers have a regular contractor’s license, even if waterproofing contractors don’t require special licensure from the state. They should also be bonded and insured.

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Cost Considerations for Exterior Basement Waterproofing

Exterior waterproofing can be a substantial investment, but protecting your home is often worth the cost.

Factors Affecting Waterproofing Costs

The following factors will impact your project costs:

• Basement size
• Chosen waterproofing techniques
• Local labor costs
• Mandatory permits and inspections
• The extent of existing water damage

Budgeting for Your Project

Consider the following tips when drawing up a waterproofing budget:

• Account for potential additional costs for repairs or landscaping.
• Explore financing options if necessary.
• Obtain multiple quotes from reputable contractors.
• View waterproofing as an investment in your home’s value and security.

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Maintaining Your Waterproofed Basement

Once you’ve successfully waterproofed your basement, regularly inspect and maintain the space as follows to ensure moisture resistance:

Regular Inspection Tips

• Keep an eye on gutters and downspouts for blockages. You can use gutter guards to prevent debris buildup, but you’ll still need to periodically clean your gutters.
• Monitor the grading around your foundation.
• Regularly inspect for new cracks or moisture signs.
• Test the sump pump annually.

Long-Term Maintenance Strategies

• Avoid planting water-thirsty vegetation near the foundation.
• Keep gutters and drains clean and in good condition.
• Maintain optimal grading around your property.
• Promptly address water issues to avoid escalated problems.

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Troubleshooting Common Waterproofing Issues

Even with robust waterproofing, you may still run into the following issues—here’s how to address them:

• Consistent leaks: You may need to explore additional interior waterproofing options to remedy consistent leaks.
• Cracks in foundation: Hire a professional to evaluate cracks emerging in your foundation.
• New dampness: Inspect your drainage systems for blockages if you notice new dampness.
• Sudden flooding: If your basement suddenly floods, immediately remove the water before determining the cause.

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Additional Considerations for Waterproofing

Effective waterproofing combines different techniques, but you also need to understand your environment to choose the best options for long-term success. Consider the following when embarking on a waterproofing project:

• Choose environmentally friendly materials whenever possible.
• Consider how any alterations to water flow might impact your local ecosystem.
• Consider the impact of seasonal rains or snowmelt.
• Explore options such as crystalline waterproofing, which penetrates concrete to block water pathways.
• Install external sump pits in areas prone to high water tables.
• Research how different seasons can affect water levels and soil conditions.

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Our Conclusion

Exterior waterproofing is often the best solution for stubborn or recurring basement water problems. While it may have a higher upfront cost, it addresses the root cause of moisture problems by keeping water out of your foundation. This offers long-term protection and minimizes the need for ongoing maintenance compared to interior fixes. We recommend consulting with professional waterproofing contractors to explore your options.

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FAQ About Exterior Basement Waterproofing

How much does it cost to waterproof a basement from the outside?

Exterior basement waterproofing costs vary substantially by method. For example, installing an exterior French drain will cost $15–$35 per linear foot and yard regrading typically costs $900–$3,000.*

*Cost data sourced from Angi.

How long does it take to waterproof a basement from the outside?

Exterior basement waterproofing can take anywhere from a day to a week depending on the basement size and waterproofing method.

How do I know if my basement needs waterproofing?

Here are some signs your basement needs waterproofing:

• Bowed or cracked foundation walls
• Condensation on pipes or windows
• Efflorescence on concrete
• Mold or mildew
• Musty odors
• Visible flooding or standing water

Can you waterproof a basement from the inside?

Yes, you can waterproof a basement from the inside. This is often less expensive and disruptive than exterior waterproofing but may not resolve severe moisture problems.

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