The Sika Waterbar FB-125 is a fully bonded, flexible waterstop engineered for sealing construction joints in watertight concrete structures. Manufactured from a hybrid flexible polyolefin (FPO) compound, its rough-textured surface creates a mechanical and chemical bond with fresh concrete, effectively eliminating lateral water migration through vulnerable joint zones. Cast directly into the concrete during placement, the FB-125 forms a continuous, permanently embedded watertight barrier — making it a trusted waterproofing solution for below-grade structures, underground construction, water treatment plants, reservoirs, and other water-retaining applications. The streamlined installation process requires no recesses, no special reinforcement detailing, and no specialized tools, significantly reducing labor time and installation complexity without compromising long-term waterproofing performance.
Key Features
The Sika Waterbar FB-125 sets itself apart from conventional waterstop systems through its fully bonded installation method. Rather than simply spanning a joint, the FB-125 bonds directly to the surrounding concrete structure, eliminating the risk of lateral water underflow that commonly causes failures in traditional embedded waterstops.
Built from a durable hybrid flexible polyolefin (FPO) compound, the FB-125 maintains permanent flexibility throughout its service life, resisting the cracking and degradation that can compromise lesser waterstop materials over time. Its robust construction also provides reliable resistance to all natural substances found in soil and groundwater, making it well suited for demanding below-grade and submerged environments.
Installation is straightforward and efficient. The FB-125 requires no special tools, no additional reinforcement detailing, and no extra formwork recesses — reducing both labor costs and on-site complexity. Long roll lengths further minimize the number of field joints required, decreasing potential leak points and speeding up the installation process.
When integrated into a broader waterproofing strategy, the FB-125 is fully compatible with other proven Sika waterproofing and joint sealing systems, allowing engineers and contractors to build comprehensive, layered moisture protection into their structures. And in the rare event that a leak does occur, the fully bonded nature of the system simplifies leak detection and repair, providing added confidence in long-term performance.
Technical Specifications
| Specification | Value |
|---|---|
| Material | Flexible Polyolefin (FPO) |
| Thickness | > 3.00 mm |
| Shore A Hardness | 85 ± 10% |
| Tensile Strength | ≥ 6 N/mm² |
| Elongation | ≥ 400% |
| Adhesion in Peel | ≥ 50 N / 50 mm |
| Water Tightness | Tight (EN 1928, Method B) |
| Lateral Water Migration | Pass (7 bar, 7 days) |
| Service Temperature | -10°C to +40°C |
| Roll Length | 164 ft (50 m) |
Frequently Asked Questions
How is the Sika Waterbar FB-125 installed? The FB-125 is embedded a minimum of 30 mm into fresh concrete to ensure a fully bonded, watertight seal and prevent lateral water underflow. Depending on the joint type, it can be fixed directly to the formwork shutter, temporarily secured to starter bars, or anchored to fresh concrete using mounting brackets. Always follow Sika’s method statements and working instructions, adjusted to actual site conditions.
Can the FB-125 be used in both vertical and horizontal joints? Yes. The FB-125 is suitable for a wide range of construction joint configurations, including slab-to-slab, slab-to-wall, and wall-to-wall joints. This versatility makes it a practical choice for complex concrete structures where joint orientation varies throughout the project.
Is UV exposure a concern during installation? Yes. The FB-125 is not permanently UV or weather resistant. If concrete cannot be placed within 90 days of waterstop installation, the product must be protected using appropriate protective sheeting. Planning concrete placement schedules around this limitation is recommended to maintain product integrity.
What jointing methods are approved for the FB-125? The FB-125 can be jointed using thermal welding equipment, adhered with SikaProof Sandwich Tape-50, or mechanically fixed using a clamping bar set. Factory-fabricated joins are always preferable where possible to minimize field joint failures and maintain a continuous watertight seal.
Is the FB-125 compatible with other Sika waterproofing products? Yes. The FB-125 is designed to integrate seamlessly with other proven Sika waterproofing and joint sealing systems, allowing contractors and engineers to create a comprehensive, multi-layer moisture protection strategy tailored to the specific demands of the structure.
What types of structures is the FB-125 best suited for? The FB-125 is ideal for any structure where long-term watertight construction joints are critical. Common applications include underground structures and basements, water treatment plants, reservoirs, swimming pools, retaining walls, and other water-retaining concrete constructions exposed to continuous or intermittent hydrostatic pressure.
Does the FB-125 require any special tools for installation? No special tools or equipment are required for standard installation, which is one of the key advantages of the FB-125 system. This simplifies site logistics, reduces the skill threshold for installation crews, and helps keep labor costs under control on large or complex projects.
What happens if a leak develops after installation? Because the FB-125 is fully bonded to the concrete structure, leak detection and repair are significantly easier compared to unbonded waterstop systems. The bonded interface allows repair teams to pinpoint the source of ingress more accurately and apply targeted remediation, reducing the scope and cost of any corrective work.
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