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External Wall Insulation & 60 Effective Life

Background

 

The British Board of Agrement (BBA), in circa 2012, created a programme for clients requesting a 60-year effective life statement for their Certificate. This was either conducted as an initial assessment or as a retrospective increase in the effective life period given in an existing certificate. It is not a guarantee and does not ensure that the system or product will perform for over 60 years.

Certain systems and materials can be assessed based on known service life, either directly, indirectly by analogy or through proven accelerated age testing combined with a statistical regression analysis. Considering the possible methods of assessment, the BBA decided to evaluate the 60-year effective life of an external wall insulation (EWI) system via an alternative, less scientific, theoretical approach.

 

There are several EWI systems on the UK market that have been assigned 30 years effective life. This has been proven through long established testing regimes, but clients are increasingly looking for BBA Certificates to state 60 years effective life. Rather than developing testing and statistical regimes that can reproduce 60 years real world service, the BBA have simply opted for a more hypothetical methodology, a ‘top up’ assessment to extend the quoted period of effective life. This is a simple approach that does not evaluate or certify the systems durability or robustness, but basically estimates that the system can feasibly perform as required for that 60-year period.  

What Makes a 60 Year Effective System Different?

It is commonly known within the EWI industry that a system can establish 30-year effective life via the use of established artificial weathering techniques such as those contained withing ETAG004 Guideline for European Technical Approval of External Thermal Insulation Composite Systems with Rendering. The default position is that the effective life statement is fixed at a maximum of 30 years, unless it can be demonstrated through other evidence, that an extension is justified. The BBA do not consider extending the weathering cycles and increasing the severity of the cycles a viable approach to justification, therefore, neglecting the effects of climate change, hurricanes, hailstorms, heatwaves, blizzards etc. Instead, the BBA prefer a conjectural approach, upon which the following aspects are required to demonstrate the EWI’s systems ability to achieve a 60-year effective life:

  • Enhanced durability
  • Weathering testing in accordance with ETAG004 (as standard for 30 year)
  • Enhanced specification of materials for extended life
  • Insulation fixings must have a stainless-steel central pin
  • Certain beads and profiles must be stainless steel
  • Enhanced structural specification
  • Increased safety factors
  • Mechanical fixings are to be fixed through the reinforcement layer
  • Insulation adhesive must be used
  • Enhanced supervision of workmanship during installation
  • Yearly surveillance and maintenance recommendations
  • Training for the maintainers

Similarities Between a 60 Year Effective Life System and a 30 Year Effective Life System?

Due to the BBA only conducting a ‘top up’ assessment, there are minimal changes to the system required to achieve the 60-year effective life status. With the following remaining the same;

  • Insulation
  • Beads in many instances
  • Fixings (apart from central pin)
  • Basecoats
  • Reinforcement
  • Primers
  • Finishes

 In many instances, the systems are identical apart from adaptations already identified. Even the enhanced supervision of installation, yearly surveillance and maintenance recommendations are not unfamiliar procedures within the EWI industry. These practices are typical requirements of most, if not all, system designers when installing their 30-year effective life systems on high rise buildings and are therefore not innovative or unusual.

Who has 60-Year Effective Life Statements?

 

Due to the simplicity of demonstrating a systems 60-year durability, with minimal associated cost, most system designers have the 60-year statement contained within some, if not all their certificates:

  • Alsecco
  • Envirowall
  • K Systems
  • Soltherm
  • STO
  • Wetherby

Conclusion

 

Achieving 60-year effective life statements within a system designers BBA certification is an uncomplicated and simple process. System designers, such as Soltherm, only specify adhesive and mechanically fixed systems and adopt a stringent high-rise policy. This high-rise policy already requires enhanced site inspection, yearly surveillance and maintenance. Therefore, there are very minimal changes required to achieving 60-year effective life for system designers of this type.

Whilst the changes, stainless steel components, are not innovative, having been available for decades, they are positive from a corrosion perspective. This along with the enhanced structural specification makes a 60-year effective life system an attractive prospect but not a guarantee.

The BBA 60-year effective life programme should do a lot more to prove and ensure that the system has the guaranteed durability to withstand all the effects of the UK’s current environment and predicted future climate changes. This could be achieved through increased artificial weathering and durability testing, supported by statistical regression analysis. Currently, the theoretical methods adopted by the BBA are nowhere near providing this 60-year assurance.

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