Bitumen membrane

The Sika Group has acquired a majority stake in Index Construction Systems and Products, a leading Italian manufacturer of roofing and waterproofing systems. Index is known for its superior range of high-quality bitumen membrane solutions. As a popular roofing material choice, bitumen offers versatility, durability, cost-effectiveness and, above all, it is highly waterproof. 

What should be considered when choosing a bitumen membrane? 

Key factors 


The temperature, exposure and local weather determine the type of compound type – be it elastomeric, plastomeric, elastoplastomeric or oxidised bitumen. 

Intended use 

  • Smooth surfaces such as talc, sand and PE foil are indicated for ballast systems, or as a base sheet in a multi-layer system. 
  • Covered membranes such as granulated surfaces protect the compound and can be used as an exposed layer. 

 Performance requirements 

  • Polyester increases the strength and elongation. 
  • Glass fibre increases the dimensional stability. 
  • Aluminium works as a vapour barrier. 

* The type of reinforcement defines the system build-up and whether the membrane should be applied in a single or double layer. 

 Life expectancy 

Aging tests are strongly recommended, as are tests to check thermo-oxidisation. 

 Project limitations 

These include fire performance, local approvals, certifications, required anti-root materials and safety considerations during the application process. 

Product variables 

Key variables of bituminous membranes: 

  • Cold flexibility: Directly related to weather conditions and the life expectancy of the membrane. The lower the flexibility, the higher the durability. 
  • Reinforcement: Strength (tensile force), elongation and tear-and-shear resistance. 
  • Top surface: Smooth for non-exposed roofs, below-ground applications or self-protected surfaces for exposed roofs and the upper layer in multi-layer systems.  

Issue: Choosing the correct bitumen membrane.

Solution: With over 100 years of waterproofing experience, Sika identifies the factors and variables to consider.

For more information, contact Sika: 

Tel: +27 31 792 6500 





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