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24 November 2017

Timber Claddings and the Fire Code

We now have facade and cladding restrictions for all commercial construction with occupiable spaces above 7m, and residential builds above 10m — meaning more limited and cost prohibitive cladding options.

Detailed blog image Fireshield november

In the wake of the tragic Grenfell Tower fire that claimed 71 lives in the UK, and the Lacrosse tower fire in Melbourne that caused $15million in damage, passive fire and combustible claddings have become hot topics. What lessons can we learn from these past mistakes and what tools do we have to avoid repeating them?

Whilst we can try to specify what we think is the best product for the job, it can be very difficult understanding the testing and certification limitations. As a result, specification changes are rife throughout the construction sector — often driven by budget constraints, attempts to maximise profits or support favoured suppliers. This is generally considered the root cause of the aforementioned disasters and many current litigations in New Zealand.

Many prominent architectural firms in New Zealand still maintain firm control of their specifications. Sadly, this is seldom the case in Australia or the UK. Increasingly in New Zealand, we are beginning to see changes to specifications being made without the specifier's knowledge, or with misinformation provided by aggressive suppliers with poor ethics.

Remarkably, the NZBC facade legislation and requirements were revised and clarified just one week prior to the Grenfell tower disaster. The previous facade allowances for sprinklered buildings under 25m was removed, and a clarification of what constitutes a 'facade system' was made. We now have facade and cladding restrictions for all commercial construction with occupiable spaces above 7m, and residential builds above 10m. 

A typical townhouse can easily exceed this height. Cladding options for these situations have become very limited or cost prohibited. Resene and Fireshield have been working hard to find solutions, and are very excited to offer the only exterior paint system currently available in NZ for timber claddings. The Fireshield Exterior System is a BRANZ certified paint solution that meets the “Type B” cladding requirements. This allows for combustible claddings, battens, rigid air barriers and bracing ply to be used on all buildings over 1m from the relevant boundary.

Resene and Fireshield are now working on a greater range of top coat options, to provide enhanced durability and easily maintained solutions for tall buildings. This gives architects and designers the freedom to choose sustainable materials in the shape and form they prefer.

Ultimately, passive fire products and especially claddings should never be changed post consent without thorough and documented consultation with all relevant stakeholders including the fire engineer, TA and fire service. The potential liability for anyone incorrectly substituting passive products is enough to sink most firms and may carry significant personal liability outside the scope of your company’s professional indemnity, as has been demonstrated by many overseas real fires recently. In these situations, it’s generally the main contractor that’s left with the cost of remediation and outdrawn costly legal battles. Moving forward, we can expect main contractors to be more resistant to accepting specification changes and the adoption of better quality assurance processes for products used by their subcontractor. Independent third party inspections of passive fire installations are common overseas, and are now being adopted by many NZ contractors, as a way to reduce potential liability and ensure compliant high quality workmanship.

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