STRUCTURAL ELEMENTS


The devil is in the detail: fire protection processes for timber


Howard Morris at Trade Fabrication Systems explores the relative performance benefits of fire-retardant surface coatings and pressure treatments for timber, and explains the merits of an alternative process


construction, but it has a major flaw – it burns. As fire protection drives design, it is integral for architects to utilise products and solutions that meet the needs of the market, while guaranteeing adherence to Building Regulations.


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The Euro Class system determines a product’s fire performance by measuring it against a comprehensive set of characteristics. As wood is an organic combustible material, it will never achieve Euro Class A1 or A2 non-combustibility. With this in mind, the highest fire-retardant classification wood can receive is Euro Class B which can be successfully achieved by embracing timber technologies and enhancing the substrate. There are two main types of fire-retardant timber treatment that can be used to achieve compliance; pressurised treatment and surface coating.


Scratching the surface of FR coatings


One of the most common forms of fire protection for timber substrates is the application of fire retardant coatings. Cost effective and compliant, the coating can be applied to any wood-based product through a traditional onsite coating process. Protecting the appearance of the substrate, while also guaranteeing its structural integrity remains intact, surface coating is an ideal way to ensure timber complies with Euro Class specification. However, true compliance is entirely dependent on the coating applied and the timber substrate originally tested. For example, if the type of timber used differs to the one that was tested, this solution will be non compliant – as the fire retardant coating may not perform as expected in


ADF DECEMBER 2019


practice. The same is also true if the coating is not applied to the exact specification and consistency of that tested. So, while fire retardant coatings represent a cost effective route to delivering fire protection performance, there remains room for error onsite, particularly in relation to the quality control of workmanship.


Under pressure to perform Pressure treatment is an alternative method to Building Regulations compliance. A time consuming process, the timber substrate is impregnated with chemical preservatives to enhance its durability and withstand damage and exposure to the elements. The pressure treatment method should


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dmired for its rustic appearance, strength and cost, timber is an attractive material for use within


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