FLEXOBIT Waterproofing for Foundations and Retaining Walls
Waterproofing of foundations and retaining walls is critical for structural safety and the long-term durability of load-bearing systems. Thanks to its high elasticity and SBS (Styrene-Butadiene-Styrene) polymer-modified composition, Flexobit provides a reliable and long-lasting waterproofing solution for these demanding applications.
1. Flexobit Application on Foundation Slabs
Surface Preparation
After the lean concrete (blinding concrete) has been poured, the surface should be mechanically finished to achieve a smooth substrate. The surface must be completely dry before waterproofing begins.
Flexobit Features
- SBS polymer-modified composition
- Homogeneous thickness of 5 mm
- Free from reinforcement felt and filler materials
- Up to 1600% elongation in all directions
- Maintains flexibility even at –25°C
- PE film-coated underside for full adhesion
- Sanded upper surface to improve joint performance
- Self-healing properties
- Three-dimensional formability for complex detailing
Application Method
For foundation slabs, the membrane is installed using the loose-laid application method.
- Longitudinal overlaps: 10 cm
- Transverse overlaps: 15 cm
- Overlaps are heat-bonded using a torch
- The bitumen should not be directly burned during installation
This installation method allows the waterproofing system to accommodate settlement and structural movement while maintaining continuous protection.
2. Flexobit Application on Retaining Wall Concrete Surfaces
Surface Preparation
After the concrete has cured and formwork has been removed:
- Oil, rust, dirt, dust, and loose particles must be removed
- Honeycombs, segregation areas, and construction joints should be repaired using suitable repair mortar
- Tie-rod holes should be filled to a depth of 5–10 cm
- A chamfer fillet measuring 3–5 cm should be formed at foundation-to-wall transitions
Primer Application
A layer of Flexobit Primer should be applied to the concrete surface.
Coverage rate: Minimum 0.400 kg/m²
The primer is applied cold and must be allowed to dry completely before membrane installation.
Installation of the Flexobit Waterproofing Membrane
- Longitudinal overlaps: 10 cm
- Transverse overlaps: 15 cm
- The membrane is fully bonded across the entire retaining wall surface
- Heat is applied carefully without burning the bitumen
Full adhesion ensures maximum waterproofing performance and resistance to groundwater pressure.
Advantages of Flexobit Waterproofing Systems
Integrated Protection for Foundations and Retaining Walls
Flexobit creates a continuous waterproofing barrier that protects both horizontal and vertical structural elements.
Exceptional Flexibility
Its high elasticity allows the membrane to adapt to structural movement without cracking or losing waterproofing performance.
Long-Term Waterproofing Performance
The SBS-modified composition provides durable protection against water infiltration, helping extend the service life of the structure.
Frequently Asked Questions (FAQ)
How is Flexobit installed beneath foundations?
Flexobit is installed in a single layer over lean concrete using the loose-laid method. Membrane sheets are overlapped by 10 cm longitudinally and 15 cm transversely, with bonding performed only at the overlap joints.
Why is Flexobit fully bonded on retaining walls?
Retaining walls are exposed to greater hydrostatic pressure and structural movement. Full adhesion across the entire surface provides maximum waterproofing reliability and prevents water migration behind the membrane.
Why is primer applied before installing Flexobit?
Flexobit Primer improves adhesion between the concrete substrate and the waterproofing membrane, ensuring long-term bonding performance.
Does Flexobit maintain flexibility in cold weather?
Yes. Flexobit retains its elasticity even at temperatures as low as –25°C, making it suitable for demanding climatic conditions.