SealBoss® SwellCaulk™ – Caulk-Grade Swelling Waterstop for Cold Joints and Concrete Sealing

An Overview of SealBoss SwellCaulk

In modern concrete construction, water intrusion is one of the most persistent threats to structural durability and performance. Construction joints, cold joints, and pipe penetrations are particularly vulnerable to leakage, especially in below-grade, submerged, or high-moisture environments. Enter SealBoss SwellCaulk™—a next-generation, high-performance caulk-grade swelling waterstop developed specifically to combat these challenges.

What is SealBoss SwellCaulk?

SealBoss® SwellCaulk is a single-component, polyurethane-based, hydrophilic waterstop and leak-sealing caulk grade swelling waterstop paste designed for easy application and long-lasting waterproofing. The product is engineered to react with water by expanding up to 350% of its original volume, effectively sealing gaps and voids in concrete joints.

• Single-component system – no mixing required
• Water-activated expansion for maximum sealing power
• Extremely adhesive – bonds to concrete, even when rough or damp
• Flexible and moldable to irregular joint surfaces

Packaging Formats for On-Site Versatility

SealBoss SwellCaulk is available in two user-friendly packaging formats:

• Cartridges – For use with standard caulking guns
• Sausages – For use with common sausage-style applicator guns

These application options allow field teams to adapt to specific project conditions and scale—from small detailing work to long joint runs on large concrete slabs or walls.

How SwellCaulk Works: Hydrophilic Expansion and Active Sealing

The core innovation behind SwellCaulk lies in its hydrophilic polyurethane composition. Upon exposure to water, this Caulk Grade Swelling Waterstop undergoes a controlled expansion, growing up to 3.5 times its initial volume while creating a permanent compression seal. This physical expansion enables the product to fill gaps and irregular surface areas, forming a dense, resilient, and water-impermeable seal.

• Self-adheres to dry or moist concrete
• Eliminates need for primers or adhesives
• Adapts to rough, porous, or irregular substrates
• Forms watertight seals even in uneven joints

SwellCaulk as a Pressure-Positive Compression Seal

Unlike conventional caulks that merely sit in a joint, SwellCaulk becomes an active barrier once confined and hydrated. Its expansion creates a compression seal, pressing outward against joint walls to establish a pressure-positive seal—blocking water flow even under significant hydrostatic pressure.

• Withstands considerable hydrostatic pressures
• Provides permanent, resilient water sealing
• Ideal for below-grade, wet, or submerged conditions

Understanding Cold Joints—and Why They Need SwellCaulk

Cold joints form when a new batch of concrete is poured next to an existing pour that has already begun to set. These unbonded seams can act as fine channels for water migration, creating long-term leakage problems.

Despite appearing solid from the surface, cold joints are inherent weak points in a concrete structure.

SwellCaulk is engineered to permanently seal cold joints. Its expanding action allows it to create a strong bond with both concrete layers, forming a continuous, flexible and active seal.

• Designed to seal cold joints in cast-in-place and precast concrete
• Seals non-bonded gaps caused by pour delays
• Creates a permanent watertight barrier at potential failure points

Superior Hose Injection System

SealBoss Injection Hose Advantage
The Inject Tube 2 Hose System is installed in concrete joints to waterproof and seal the cold joint and any cracks or voids in connection with the joint area. The SealBoss Inject Tube System seals joints watertight. The SealBoss Injection Tube Hose System is improving waterstop technology towards a zero leak tolerance. SealBoss Injection Tube is easy to install and priced with a competitive advantage in mind.

Injection Hose Design
The SealBoss Inject Tube System 2 is high quality competitively priced injection hose system with a proven track record. Inject Tube 2 is specially designed with a solid perforated PVC core and covered by two woven membranes to prevent any contamination and clogging of the inner core and to provide for an even distribution of sealant along the cold joint during the injection process.

Injectable Waterstop for Cold Joints & Construction Joints
Cold joints and construction joints in concrete structures are vulnerable areas for leaking and cracking due to water penetration. Water ingress can lead to reduced structural integrity and other issues including rebar corrosion and expansion cracks, frost and thaw cycle damages and adverse health effects cause by mold and fungus growth.

What is a Cold Joint?
A cold joint is the area that is created during the concrete pouring process when fresh and existing concrete meet.  A cold joint is caused by a lack of bonding / cohesion between the old and new concrete.  The cold joint is created when the original batch of concrete has begun to set (or is fully cured) before the next fresh batch is added. The two batches do not form a strong  bond and create a passageway for water to migrate.

Injection Hose Applications

• Water Stop and Leak-Seal Caulk for Cold Joints / Construction Joints
• Retaining walls
• Foundations
• Slabs on Grade
•  Tunnels and culverts
• Dams, Canals
• Pipe penetrations

Injection Hose  Application Advantages

• Works on Smooth, Rough, Irregular Concrete Substrates
• Horizontal & Vertical poured-in-place Concrete Joints
• Reliable and Durable
• Retro-fit and New Construction
• Can withstand high Hydrostatic Pressures
• Back-up Solution for Combination with Conventional Waterstops
• Easy to Secure and Install
• InjectTube 1 – Re-Injectable with SealBoss injection acrylate resins

SealBoss Training

• Sealboss on-site training is available to ensure your job gets done right and is successful.

Popular Cold Joint / Construction Joint Water Stop Systems Links

• Three Important Cold Joint / Construction Joint Seal Systems
• SealBoss Injection Tube System
• SealBoss SwellTape
• SealBoss SwellCaulk