A new report commissioned by Woodform Architectural spells out BCA compliance requirements for acceptable timber fire resistance. Though a combustible material, timber, when properly specified, can perform well in a fire in comparison to other materials.

Woodform Architectural specially commissioned Wood & Grieve Engineers (WGE) to produce an independent report clarifying the compliance requirements under the Building Code of Australia (BCA) for acceptable timber fire resistance. A multi-awarded engineering consultancy based in Australia, WGE has in-depth knowledge of the BCA as well as fire engineering expertise, and has helped numerous architects achieve their overall design vision in compliance with BCA rules.

WGE’s report, ‘Confused? A Quick Guide to Timber Fire-Resistance Regulations’ offers a basic overview of the performance requirements of timber products; applicable BCA deemed-to-satisfy provisions; and alternative solutions relating to wall and ceiling linings as well as external wall cladding that meet fire regulations.

Excerpts from the WGE report:

Timber products are generally Group 3 or 4 materials, fire retardant timbers are expected to be Group 2 materials. The Group material of specific products needs to be confirmed by compliance testing provided by the manufacturer.

Following the Lacrosse fire in Melbourne in November 2014, Fire Brigade and governing bodies have adopted a stance not allowing Alternative Solutions relating to the use of combustible material in external building façades. Therefore all combustible external façades in Type A and B buildings have to be constructed in accordance with the Deemed-to-Satisfy Provisions and be attachments to fire rated external walls.

When wood is exposed to fire or high temperature, the surface of the wood initially ignites and burns rapidly. The burned wood forms a layer of char, which acts as a layer of insulation for the solid wood below. The initial burning rate decreases to a slower steady rate, which continues throughout fire exposure.

The char layer does not usually burn because there is insufficient oxygen in the flames at the surface of the char layer for oxidation of the char to occur. The insulating qualities of timber mean that although the temperature at the char layer may be 300°C, the temperature of the inner wood is considerably lower.

Depending on the thickness of the timber and type of timber used, a fire may cause charring of the outer layer while the inner layer maintains structural stability of the structure.

Woodform Architectural’s specially commissioned report explains misconceptions about timber fire resistance, relevant fire codes for timber lined walls and ceilings, and alternative solutions that comply with the Building Code of Australia.

The full WGE report ‘Confused? A Quick Guide to Timber Fire-Resistance Regulations’ can be accessed online on the Woodform Architectural website.