The importance of correctly specifying EuroClass B Fire Treatment on Timber Cladding

With timber being such a versatile product, and the ever popular material for use in external cladding, it comes as no surprise at NORclad we see conflicting specifications. We take a huge number of phone calls asking for advice when it comes to what can, and cannot be applied to timber cladding.

An ever increasing number of projects are now requiring External Timber Cladding to meet EuroClass B spread of flame, at NORclad we work closely with architects, planners and contractors in generating Timber Cladding NBS Specifications and therefore we want to be able to offer the most up to date advice and guidance. Fire treatment can be carried out in a number of ways, NORclad have selected and tested the most suitable of those dependant on species and scenario required;

  • Factory Spray & Brush Applied Fire Treatment
  • Pressure Impregnated Fire Treatment
  • On site application
  • “Dipping”

Factory Spray & Brush applied Fire Treatment

When working with NORclad Lite and NORclad Brunnea Pressure treatments, an additional pressure treatment for EuroClass B would not be achievable. On species such as Siberian Larch, and European Redwood, NORClad offer application through a Factory controlled system to EuroClass B through an ISO 9001 & 14001 audited Spray & Brush Line, as per the Pressure Impregnated process, the treatment is designed to last for the life of the building and no maintenance is required.

A more labour intensive process than pressure impregnation, every board going through the line will have a consistent application of fire treatment to all faces.

At NORclad we wanted to ensure a full due diligence was carried out, and to ensure full compatibility alongside the NORclad Lite and NORclad Brunnea preservative treatment. In order to do this, we took it upon ourselves to get independent testing carried out at Warrington Fire.

Warrington Fire are global leaders in fire safety, through their UKAS accredited laboratories they offer independent third party certification for EuroClass B Timber Cladding.

From carrying out an Audit on the NORclad process in house, checking the control and monitoring processes in place and looking at the application used in coating through spray and brush application.

Finally on to full testing panels in a cladding scenario at Warrington Fire laboratories, it is only at this point that EuroClass B certification along with full test reports were issued, showing the NORclad High pressure Brunnea & NORclad Lite preservative treatment and EuroClass B fire treatment, on a single certificate.

Fire Protection 6

Pressure Impregnated Fire Treatment

A combination of high pressure impregnation in a treatment cylinder followed by heat curing under controlled conditions, the Sentrin FRX product is our choice for Fire Treating a number of species including Canadian Western Red Cedar and Abodo to EuroClass B. The treatment is designed to last for the life of the building and no maintenance is required.

With the high pressure impregnation pushing the treatment into, and around the packs of timber within the cylinder there is a consistent uptake within the packs.

Undergoing this process can create an element of wastage so we would always recommend talking to us here at NORclad when looking at volumes required on your project, as nobody wants to run out of cladding 90% of the way through an elevation!

Canadian Western Red Cedar - Header

On site application/ “Dipping” – A word of Caution!

Whilst carrying out testing with Warrington Fire we also used this opportunity to test some of the other methods that we are aware of being carried out to try and get Timber Cladding to EuroClass B.

On site application, for any form of coating, be it for Fire Treatment, or Paint, on site application makes things very difficult.

With on-site application it is very difficult to ensure a number of basic steps are carried out:

  • Humidity control
  • Contamination
  • Consistent level of application
  • Coating to all faces, not just the external face
  • Curing time (often 5-10 days required which should be complete in a controlled environment)

Dipping of timber in a fire treatment solution, (not to be confused with pressure impregnated above)

This process, as the name suggests, involves placing packs of timber into a fire treatment solution bath before removing, allowing to drip dry and potentially repeating the process if required. This process is without the benefit of high pressure closed cylinder driving the solution through the pack into the individual timbers, nor the measured and monitored approach of a Spray & Brush line.

The dipping process not only offered great inconsistency from board to board in terms of uptake, when then tested in a cladding scenario at Warrington Fire, the constructed panels only achieved the indicative of EuroClass D.

In Summary on Fire Treating Timber Cladding to EuroClass B

NORclad will continue to strive in offering the best service in supplying Timber Cladding Nationwide with constant due diligence, and testing of our products on the market. Having some of the most up to date (within last 12 months*) EuroClass B Fire Certification for Timber Cladding in the industry.

Hopefully the above summary offers an insight into some of the phrases and process that we are aware of, both good and bad!

Please feel free to get in touch if you want to talk through your current project.

*May 2020-2021

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2021-05-14T11:32:47+01:00May 14th, 2021|

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