spotted gum cladding

Fire compliance for timber cladding is an area filled with confusion. Let’s be clear, you can use timber cladding on low-rise apartment building facades.

High-rise building tragedies such as the Grenfell tower in London and the Lacrosse Building in Melbourne have left designers and builders full of doubt as to whether they should use cladding in their projects. Amendments to the NCC (National Construction Code) have ruled out using cladding deemed as combustible under AS 1530.1 on high-rise and mid-rise buildings – However, NCC concessions mean that low-rise Class 2 and Class 3 projects may still use timber cladding and remain compliant.

Sculptform Tubbs Lookout

What is combustible cladding?

Combustible cladding is a term used to describe cladding which is deemed combustible under AS 1530.1. Examples include timber cladding and some forms of composite cladding. An example of a facade solution which is deemed non-combustible is Sculptform’s Click-on Battens in Aluminium.

Where is timber cladding permitted?

Class 1 buildings are typically houses, which allow timber cladding to be used externally. These buildings are split into Class 1a, which are single dwelling houses and Class 1b, which are usually used as guest houses or hostels which ordinarily have less than 12 people living in them. While any cladding is permitted, if the project is in a bushfire prone area ensure that the required BAL rating is achieved by the timber species used.

Class 2 buildings are usually multi-storey apartment buildings. These may also be single story attached dwellings where there is a common space below.

Class 3 buildings are residential buildings other than Class 1 or Class 2. Examples are boarding houses, hostels, hotels or dormitory style accommodation.

To determine the class of a project, use this great download from the ABCB.

Timber cladding is permitted on Class 2 and Class 3 buildings, according to concessions in the NCC. Certain concessions which have been around for decades allow for the use of timber cladding, provided other conditions are met.

Along with classes, buildings are also assigned a Type of Construction – determined by the rise in stories above and including the ground level. Type A is the most fire-resistant level and Type C is the least. The following table is used to determine a building’s type. 

Table C1.1

Building Class
Rise in Storeys
2,3,9
5,6,7,8
Type of Construction
4 or more
A
A
3
A
B
2
B
C
1
C
C

 

 

Now that all makes sense so far, right?

This is where we bring in the big guns and quote Boris Iskra, National Codes and Standards Manager for Forest and Wood Products Australia (FWPA) –

“Since the introduction of a “Concession” for timber-framed construction systems in 1994 (BCA 1990 – Amdt 7) for Class 2 apartment buildings and recently (NCC 2014) for Class 3 buildings (e.g. hotels, motels, backpacker accommodation etc.), the use of timber products has been permitted as external timber cladding for 3-storey Class 2 and 3 buildings, and 4-storey if the lowest storey is constructed of concrete or masonry and used for car parking, under the Deemed-to-Satisfy provisions in non-sprinkler protected buildings.”

You can see his entire reasoning behind why timber cladding is acceptable for Class 2 and Class 3 low-rise buildings here.

The amendment that lets this happen

For Type A construction, the NCC 2016 Amendment 1 Specification C1.1, Clause 3.10(a) states –

“3.10 Class 2 and 3 buildings: Concession

(a) Class 2 or 3 building having a rise in storeys of not more than 3 need not comply with Clause 3.1(d) of Specification C1.1 and the requirements of C1.9(a), (b) and C2.6 for non-combustible material, if it is constructed using—
(i) timber framing throughout; or
(ii) non-combustible material throughout; or
(iii) a combination of (i) and (ii),

provided—

(iv) *****
(v) any insulation installed in the cavity of a wall required to have an FRL is non-combustible; and
(vi) the building is fitted with an automatic smoke alarm system complying with Specification E2.2a.”

Sculptform 30 Explanade

How the amendment works – and what it means for your project

This amendment means that 3-storey Class 2 and Class 3 timber-framed buildings fitted with an automatic smoke alarm system do not need to comply with the following requirements for Type A construction:

  • Specification C1.1, Clause 3.1(d) – concrete, masonry or fire-protected timber requirements for loadbearing internal walls and loadbearing fire walls,
  • Clause C1.9(a) – non-combustible external walls and common walls, including all components incorporated in them including the façade covering, framing and insulation; the flooring and floor framing of lift pits; and non-loadbearing internal walls where they are required to be fire-resisting.
  • Clause C1.9(b) – non-loadbearing, shafts (e.g. lift, ventilating, pipe, garbage or similar) to be of non-combustible construction, and
  • Clause C2.6 – the non-combustible material requirements for vertical separation of openings in external walls.

External walls must however, still comply with other fire-resisting construction requirements in the NCC (eg. 90/90/90).

By not being required to comply with these requirements, Class 2 and Class 3 buildings are able to use timber cladding on exterior walls, allowing designers to specify Sculptform’s Tongue & Groove Cladding to create a feature timber facade that remains NCC compliant.

This article is based on Sculptform’s interpretation of the NCC, be sure to always check with the fire engineer/certifier on your project. 

timber ceiling cladding

A big thanks too –