External Wall Insulation System Designers meet with the BBA to discuss Dry Fix Systems

Mitch Gee – INCA Chairman

The BBA called certificate holding system designers to a meeting on the 7 August to discuss dry fix systems. The majority of UK external wall system designers were represented at the meeting.  Paul Valentine, the BBA’s Director of Technical Excellence presented to the group.

Paul explained that for the BBA to become aligned with European Technical Approvals there was a requirement for system designers to provide evidence that dry fix systems did not suffer from settlement. Such settlement is potentially a result of the flexing of fixings caused by the bending moment as a result of the weight of the render system. The majority of the audience believed this was not necessary, as dry fix EWI systems had been used installed in the UK for over 30 years without any evidence of failure caused by this phenomenon.

European Systems

Dry fix systems are not approved in continental Europe. This is because there is no market for dry fix systems in continental Europe. In Germany, the use of heavy dash systems is very rare and the market is predominantly thin coat render systems.

It is critical with thin coat render systems that the insulation is applied perfectly flat. To achieve this a bedding mortar is required.  In the early days of the UK market when EWI systems were predominantly thicker dash systems, there wasn’t the same need to ensure the insulation was fitted perfectly flat. Therefore in Germany there has always been need for a bedding mortar and no demand to develop dry fix systems.  Some may argue that with a heavy dash system the risk of settlement of would be greater due to the heavier render finish, although there is little evidence to support this.

I believe that the consensus of opinion that on high rise buildings, the additional resistance to wind load that an adhesive mortar might provide and its use in thin  coat render systems it may be considered as best practice, but this is certainly not the case for low rise buildings with thicker render systems.

Calculating the performance of a system

Notwithstanding this, Paul demonstrated three theoretical methods by which the performance of the system could be demonstrated, each one making an allowance for the insulation to assist in limiting the bending moment of the fixing. He described the three method as:

  1. Strut and Tie
  2. Cantilever
  3. Finite modelling.

Paul recommended the use of the cantilever model as it was the easiest to calculate. The strut and tie is more complicated, but would provide a more accurate result that is more favourable to the system designer. The most accurate method would be the finite modelling but its complexity would probably make it impractical for this purpose.

It will be possible for the BBA to arrange testing but this practical method of assessment would be costly and expensive and therefore unlikely to be adopted by any of the system designers.

Paul was open to other methods of calculation, and offered the option of the BBA undertaking the calculation or to receive the calculations submitted by system holders. Either way he did not expect the cost to be greater than a few hundred pounds.

View from INCA

I believe the industry would prefer not to have to undertake this exercise at all as they believe that there is no evidence that there is a problem. If it has to be done in the interests of European harmonisation then we expect the BBA to provide us with the most efficient and cost effective solution and provide the service for a reasonable cost.

The industry is pleased that the BBA is operating a more open policy of engagement and consultation before imposing their will. INCA understands that the BBA has a difficult job, consulting with the industry as a whole but having to retain client confidentiality, ensure all certificates are treated equally and to ensure continual updating. This is a challenging task, and as an industry we need to assist them in this endeavour.

Did you know that EWI will save the world?

Last week at the INCA AGM we were delighted to welcome Andrew Warren from the British Energy Efficiency Federation. A man who has been working across sectors in energy efficiency for his whole career, Andrew entertained us with his take on the value EWI brings to the world. He told the meeting that energy use in the UK is reducing substantially, which has an obvious impact on the health of the planet. He described how measures such as EWI are key to this reduction, and those who work in this sector must feel proud of the contribution we make.

Aside from Andrew Warren’s fascinating talk, the meeting heard about the work that INCA is doing for its members. This includes engaging with Government stakeholders such as BEIS and MHCLG both formally – consultation responses, and informally to ensure that our industry is represented. Mitch Gee, Executive Chairman also described the work of the Technical Committee in engaging with the BBA and BRE. There is clearly a lot going on at the moment!

A highlight of the meeting was the announcement of the INCA Awards shortlist. Anna Wesson, INCA Manager, reported a high number of entries – over 70, and the challenges facing the judges when they shortlisted. A quick reminder that tickets are now on sale for the event on 1 November in Manchester.

A key topic of discussion at the meeting was the Government Consultation on the use of combustible cladding on residential buildings above 18 metres. This closes on Tuesday 14 August, and in order to ensure the INCA response is as representative as possible, we value your input. Please get in touch if you have any comments you would like to make.

The AGM elected Mitch Gee to continue as Chairman at INCA for another year. This will allow him to continue much of the work he has started in terms of raising the profile of the Association and recruiting new members. The Board of Management also remains the same.

Independent Review of Building Regulations and Fire Safety – Final Report

Mitch Gee, Executive Chairman

The much-anticipated Independent Review of the Building Regulations was published last week. I have yet to read the full report but will endeavour to do so over the coming weeks and submit a fuller response to its contents.

Since her interim report in December, Dame Judith Hackitt has unearthed further evidence that the regulatory system for high rise is not fit for purpose. It does not just relate to cladding systems but for the industry as a whole.

The report was damning of the industry listing key issues for its failure:

  • Ignorance
  • Indifference
  • Lack of clarity and responsibility
  • Inadequate regulatory oversight and enforcement tools

She states there needs to be a clear model of risk ownership with clear responsibilities for the client designer, contractor and owner. It must be ‘outcomes-based’ rather than based on prescriptive rules and complex guidance with serious consequences for those who try to ‘game the system’. The model is dependent on competent people thinking for themselves and taking responsibility for their decisions. This is a breath of fresh air in our ‘tick box’ society where we are guilty of hiding behind guidelines that are at best confusing and at worst contradictory.

The report states the building must be considered as a system and not just a collection of products stitched together. Transparency of information and an audit trail. I am amazed in my own experience, how poor many of the archives are for construction projects. In an era of digital technology, one would expect the opposite, but contractors appear to invest very little in keeping good ordered records.

The report calls for systematic change which will require legislative change and it should not only consider new buildings, but look at our existing housing stock.

One has to compliment Dame Judith Hackitt on her ability to grasp the weaknesses in the current systems and culture of the building industry that results in ‘a race to the bottom’ for the construction and refurbishment of housing. We live in a tick-box culture that invades our society, the construction industry being no different in this regard. Dame Judith appreciates that there needs to be a shift change in this culture. It’s a big ask – can it be achieved?

Dame Judith, an Engineer by profession provides a pragmatic rational approach to solving some of the systemic failings in the system which ultimately resulted in the tragedy of Grenfell. She proposes to do this without restricting the industry to a limited range of products it can use on high rise cladding. As an industry we wish to build exciting, varied buildings, cost effectively and without compromising on safety. The report’s proposals should allow us to do that.

The politically more palatable solution however, is to only use non-combustible products over 18m. This may result in unnecessarily limiting the options for exciting design for architects, creating capacity issues and resultant inflation in the supply chain. We are already seeing price rises well above inflation in the supply of some non-combustible elements of high rise cladding. This will not solve the systemic problems that Dame Judith Hackitt has identified and most of us agree exist.

We wait therefore as the government consults on whether to ban everything but non combustible materials on high rise buildings.

It would be great to get feedback from the membership before we formulate INCA’s official position.