Project Overview

At Zavza Seal, we recently completed a large crawl space waterproofing project for a homeowner in Far Rockaway, NY. The property was experiencing ongoing water intrusion through cold joints and cracks in the crawl space floor, creating excessive moisture and raising concerns about mold growth, odors, and long-term structural damage.

Our team designed and installed a complete waterproofing system to collect groundwater, relieve hydrostatic pressure, and keep the crawl space dry year-round.

The Problem: Water Entering Through Crawl Space Cold Joints and Floor Cracks

The homeowner noticed recurring water seepage in the crawl space after heavy rainstorms. Water was entering through the cold joints where the foundation walls met the floor slab. There was also a significant crack running across the crawl space floor from east to west.

Over time, the moisture created several concerns:

• Standing water in parts of the crawl space
• Damp conditions and elevated humidity
• Increased risk of mold growth
• Musty odors entering the living space
• Potential foundation deterioration
• Concerns about future property damage

Like many homes in coastal areas such as Far Rockaway, groundwater pressure was forcing water through weak points in the foundation system.

Our Solution: Complete Interior French Drain and Sump Pump System

After a detailed inspection, our team recommended a full interior waterproofing system designed to capture water before it could accumulate inside the crawl space.

Step 1: Trench Excavation and Concrete Removal

To begin the project, our crew used diamond saw blades to cut and remove approximately 6 inches of concrete along the crawl space perimeter walls.

We also opened the large floor crack and created a trench along its entire length. This allowed us to install a traverse drain that would collect water from the center of the crawl space, not just the perimeter.

Once the concrete was removed, we excavated the trench and removed all soil and debris.

Step 2: Interior French Drain Installation

We installed approximately 130 linear feet of perimeter French drain along the crawl space walls.

In addition, we installed approximately 45 linear feet of traverse drain across the crawl space floor to connect the east and west sides of the drainage system.

The system included:

• 2-inch gravel base
• 4-inch perforated PVC drain pipe
• Soil separator fabric to prevent clogging
• Clean gravel surrounding the drainage pipe

This design allows groundwater to enter the drainage system and move efficiently toward the sump pump basins.

Step 3: Dual Sump Pump Installation

To provide reliable water removal, we installed two new sump pump basins.

Each basin received:

• Heavy-duty cast iron sump pump
• High-efficiency 1/2 HP motor
• Check valves
• Dedicated discharge plumbing

The dual-pump setup provides additional protection during periods of heavy rainfall and high groundwater conditions.

Water collected by the drainage system is automatically pumped away from the foundation through new discharge lines.

Step 4: Delta Membrane and Vapor Barrier Protection

To improve moisture control, our team installed a dimpled Delta drainage membrane along the crawl space perimeter.

The membrane was extended below the drainage system and approximately four inches above the slab surface.

This allows any incidental water entering the foundation wall area to flow directly into the drainage system.

We also installed a vapor barrier above the system to help reduce moisture vapor transmission through the crawl space floor.

According to the U.S. Environmental Protection Agency, controlling moisture is one of the most important steps in preventing mold growth and protecting indoor air quality.

Source: EPA Mold and Moisture Guidance

Step 5: Concrete Restoration

After the waterproofing system was installed, our crew restored the crawl space floor with new 4-inch thick, 4,000 PSI concrete.

The concrete was finished flush with the existing slab, creating a clean and durable surface while protecting the drainage system below.

Step 6: Exterior Concrete Joint Sealing

As part of the project, we also sealed the exterior concrete slab joints around the home.

Our process included:

• Cleaning all joints
• Filling joints with compacted sand
• Applying self-leveling sealant
• Finishing with a protective sand cover

Proper joint sealing helps reduce water infiltration around the foundation and protects exterior concrete surfaces from deterioration.

The National Ready Mixed Concrete Association notes that properly sealed concrete joints help limit water penetration and extend the life of concrete structures.
Source: National Ready Mixed Concrete Association Concrete Resources

Need Crawl Space Waterproofing in Far Rockaway, NY?

If your crawl space has standing water, musty odors, foundation seepage, or excessive moisture, Zavza Seal can help. Our team installs custom waterproofing systems designed for the unique groundwater and coastal conditions found throughout Far Rockaway, Queens, Long Island, and the surrounding areas.

Contact Zavza Seal today to schedule a professional crawl space waterproofing inspection and learn how we can help keep your home dry and protected year-round.