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A Guide to Waterproofing a Crawl Space

Your home is your sanctuary, a place of comfort and safety, but beneath your house, the crawl space may harbor potential problems. This neglected area can become damp and attract mold, pests and structural damage over time. A well-maintained, dry crawl space is crucial for the longevity and health of your home. 

From waterproofing your crawl space to understanding moisture causes and implementing solutions like French drains, ventilation, insulation and maintenance, there are things you can do to keep your crawl space protected and your home safe for you and your family. 

What is a Crawl Space?

The picture depicts a crawl space. There is concrete walling and wooden infrastructure.

A crawl space is a foundation that lifts a home off the ground, typically three to four feet high for easy access. It’s not a liveable area but serves as a convenient entry point for plumbing, wiring and HVAC systems. In damp climates, rather than building on a slab, this type of foundation is common to help prevent flood damage. 

However, if not waterproofed properly, the crawl space can breed moisture and mold that can be harmful to the home and its inhabitants. Many people mistakenly think that crawl spaces are inherently damp and mold-prone areas that require minimal maintenance. There’s also a frequent misunderstanding that crawl spaces have little impact on the home’s overall health and energy efficiency.

The Consequences of Neglect: Why Waterproofing Matters

Neglecting to waterproof a crawl space can have serious consequences that go beyond the crawl space itself. Here are some reasons why waterproofing is important:

  • Mold and Mildew Growth: A damp crawl space can cause mold and mildew to grow, which can damage your home’s structure and pose health risks like respiratory issues and allergies.

  • Pest Infestation: Excess moisture can attract pests like termites and rodents, which can cause further structural damage.

  • Wood Rot and Rust: High humidity in the crawl space can cause wood rot and rusting of metal appliances which can compromise your home’s stability.

  • Damage to Living Areas: Moisture can seep into the living area and cause unpleasant odors and potentially damage your property.

  • Failure to Waterproof: Neglecting to waterproof a crawl space can lead to costly repairs and decreased property value because persistent moisture problems often require extensive and expensive solutions.

Waterproofing your crawl space is not just about maintaining the area itself, but also about protecting your home and ensuring a healthy living environment for its occupants.

Signs of a Waterproofing Issue in Your Crawl Space

The picture depicts a wall with blue and black mold spots.

Identifying a waterproofing issue in your crawl space is the first step towards solving it. Several tell-tale signs can indicate a moisture problem:

  • One obvious sign is the presence of water puddles or damp areas. You might also notice a musty smell or increased humidity, both indicators of excess moisture.

  • On the walls of the crawl space, you may see water stains, peeling paint or efflorescence — a white, chalky substance that appears when water evaporates from concrete, brick or stone.

  • Fungus, mold or mildew on the floor joists are other common signs.

  • Rust on metal surfaces, deteriorating insulation or wood rot can also point toward a waterproofing issue.

  • Evidence of pests, such as termites or rodents, may indicate the presence of damp conditions.

How to Properly Waterproof Your Crawl Space

Inspection and Assessment

Conduct an Overall Inspection

The first step to waterproofing your crawl space is conducting a thorough inspection and assessment. This process will help you pinpoint the root of the moisture problem. It’s essential to inspect all aspects of the crawl space, such as the floors and walls, for signs of dampness, mold and structural damage.

Check for Leaks

You should also check the vents and openings for any signs of leaks or seepage. In addition, assess the condition of the insulation and look for any signs of rust on metal surfaces. Pay close attention to the smell, as a musty odor often indicates a moisture problem. It might be helpful to use a moisture meter to measure the humidity level in the crawl space. If it’s above 50%, it’s high enough to promote the growth of mold and mildew.

Ensure That You Have Proper Drainage

Assessing the soil and drainage around your home’s foundation is crucial in waterproofing your crawl space. Start by inspecting the ground next to your house. It should slope away from the foundation to help direct rainwater away from your home. 

If the soil is flat or slopes towards your house, rainwater may pool around the foundation and seep into the crawl space. If this is the case, you might need to regrade the yard or install a drainage system to protect your foundation.

Sealing Concrete and Entry Points

Patch and Seal Foundation Cracks

Inspect the foundation for any cracks, as they can be entry points for water. Use a wire brush to clean out the cracks and remove any loose debris. This will create a smooth surface for the sealant to adhere to. For small cracks, use a good quality waterproof masonry sealer or a concrete patching compound like DRYLOK® Masonry Crack Filler.

For larger cracks, you may need to use hydraulic cement. It expands as it dries to create a water-tight seal. Remember, fixing cracks in the foundation is not just about preventing water in the crawl space, it also helps maintain the structural integrity of your home.

Sealing Concrete

To effectively waterproof your crawl space, sealing the concrete walls is a crucial step. 

This process involves applying a waterproof sealer to protect against moisture ingress.

One of the best products to seal your concrete and keep your crawl space dry is the DRYLOK Floor & Wall Masonry Waterproofer. This high-quality waterproofer is a clear, non-pigmented masonry waterproofer specifically formulated for floor and wall applications. It penetrates deeply into the concrete and reacts with the alkali and free lime to seal the pores and capillaries of the concrete. 

Installing Vent Covers

Crawl space vents, while initially designed to let air in and out, can sometimes allow water and pests to enter, especially during heavy rains or snowfall. The solution to this issue is the installation of vent covers. Vent covers are designed to keep water and pests out while still allowing enough ventilation to prevent moisture buildup.

Ensure Doors and Access Points Are Properly Sealed

To prevent water and pests from entering, ensure all doors and access points to your crawl space are properly sealed. Use weatherstripping for doors and replace damaged or deteriorated weatherstripping promptly. For utility penetrations and larger gaps, seal with high-quality silicone or acrylic latex caulk or expandable spray foam. 

Regularly inspect and reapply sealants as needed to maintain effectiveness. Properly sealed doors and access points reduce the risk of water and pest intrusion to help keep your crawl space dry and safe.

Improving Drainage

Install a Sump Pump if Necessary

In areas prone to heavy rains or high water tables, a sump pump in your crawl space can prevent flooding. It collects excess water in a basin and pumps it away from your home. To install, dig a hole, place the basin and connect the pump to a discharge pipe. 

Make sure that the discharge location is far enough away to prevent water from flowing back. Consider a battery-operated backup pump for emergencies. Regular maintenance is crucial for efficiency and longevity.

Grade the Soil-Away From the Foundation to Encourage Water Runoff

The landscape around your home is crucial for waterproofing the crawl space. Ideally, the ground should slope away from your home to direct rainwater away from the foundation. This technique, called grading, prevents water from pooling around the foundation and seeping into the crawl space. 

To grade your yard, determine the high and low points and create a gentle slope away from the foundation. Aim for a 6‑inch slope over the first 10 feet from the foundation. Smooth the soil with a landscaping rake and consider covering it with grass or mulch to prevent erosion.

Consider Installing a French Drain for Additional Drainage

If water pooling persists after grading the soil, consider installing a French drain. It’s a trench with gravel and a perforated pipe that redirects surface water away from your home. This system is effective in saturated soil. To install, identify the water accumulation area, dig a trench away from the house, place the pipe and fill with gravel. 

Slope the pipe away from the house (1 to 2 percent gradient). Water enters the pipe, collects in the trench and drains away. Cover the gravel with sod or soil for a lawn-like surface.

Ventilation and Insulation

Ensure Proper Ventilation to Prevent Condensation

Proper ventilation in your crawl space is crucial to prevent moisture buildup, condensation, mold growth and structural damage. Ventilation can be natural (via vents and air bricks) or mechanical (using fans and dehumidifiers). Ensure a steady airflow to keep the area dry. 

In humid climates, mechanical ventilation like exhaust fans or dehumidifiers is often more effective. Install a vapor barrier on the ground to prevent soil moisture from evaporating. Regularly check and clean vents and ensure fans and dehumidifiers are functional.

Insulate Crawl Space to Regulate Temperature and Reduce Moisture

Insulating your crawl space is essential for maintaining a dry environment and preventing moisture-related issues. It helps limit condensation and regulates temperature to reduce the risk of frozen pipes in winter and keep your home cooler in summer. Use materials like fiberglass batts or rigid foam boards. Rigid foam insulation is preferred because it’s moisture-resistant and retains its insulating properties.

Maintenance Tips for a Dry Crawl Space

Regular maintenance is the key to ensuring that your crawl space stays dry, clean and free from moisture-related issues. Here are some practical steps you can take:

Routine Inspection

Regularly inspect your crawl space for any signs of moisture, such as dampness, mold or condensation on insulation. Look out for any water pooling or structural damage that might suggest a leak or poor drainage.

Check and Clean Vents

Make sure the vents that provide natural ventilation to your crawl space are not blocked. Clear out any debris or blockages and clean the vents regularly to maintain good airflow.

Check the Condition of the Vapor Barrier and Make Repairs as Needed

A vapor barrier is crucial for preventing moisture from entering your crawl space. 

Regularly inspect it for signs of damage like rips, punctures or looseness. Repair or replace it promptly to maintain effectiveness. For small tears, use vapor barrier tape. For larger damage, replace the affected area or the entire barrier. Choose a high-quality vapor barrier with a high perm rating to resist moisture penetration.

Waterproof Your Crawl Space Properly with DRYLOK

Don’t leave your crawl space at the mercy of moisture and potential structural damage. 

Protect your home and peace of mind by waterproofing your crawl space with DRYLOK. Our expert solutions are designed to provide superior moisture resistance to help ensure that your crawl space stays dry and damage-free. Act now, safeguard your home with DRYLOK and enjoy a healthier, safer living environment.

Contact us today for a retail store near you!