Section 3 - AS 3959:2018

This reference guide is not an exhaustive list of all of the requirements of AS3959:2018, and should be read in conjunction with Australian Standards AS3959:2018, AS1530.8.1, AS1530.8.2 and official test reports and assessments.

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General (Clause 3.1)

This section specifies general requirements for the construction of buildings for all Bushfire Attack Levels (BAL’s).

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Construction Requirements for Specific Structures (Clause 3.2)

- Attached structures and structures sharing a common roof space.

Where any part of a garage, carport, verandah, cabana, studio, storage area or similar roofed structure is attached to, or shares a common roof space with, a building required to conform with this Standard, the entire garage, carport, verandah or similar roofed structure shall conform with the construction requirements of this Standard, as applicable to the subject building.

 

Alternatively, the structure shall be separated from the subject building by a wall that extends to the underside of a non-combustible roof covering, and that conforms with one of the following:

(a) The wall shall have an FRL of not less than 60/60/60 for load bearing walls, and -/60/60 for non-load bearing walls when tested from the attached structure side and shall have openings protected as follows:

 

• (i) Doorways - By self-closing fire doors with an FRL of -/60/30, conforming with AS1905.1 and tested in accordance with AS 1530.4.

• (ii) Windows - By fire windows with an FRL of -/60/- when tested in accordance with AS1530.4 and permanently fixed in the closed position.

• (iii) Other openings - By construction with an FRL of not less than -/60/- when tested in accordance with AS1530.4.

• Note: Control and construction joints, subfloor vents, weepholes and penetrations for pipes and conduits need not conform with Item (iii).

 

or, 

(b) The wall shall be of masonry, earth or masonry-veneer construction with the masonry leaf of not less than 90 mm in thickness and shall have openings protected as follows: 

 

• (i) Doorways - By self-closing fire doors with an FRL of -/60/30, conforming with AS1905.1 and tested in accordance with AS1530.4.

• (ii) Windows - By fire windows with an FRL of -/60/- when tested in accordance with AS1530.4 and permanently fixed in the closed position.

• (iii) Other openings - By construction with an FRL of not less than -/60/- when tested in accordance with AS1530.4.

• Note: Control and construction joints, subfloor vents, weepholes and penetrations for pipes and conduits need not conform with Item (iii).

 

 

- Adjacent structures on the subject allotment.

Where any garage, carport, or similar roofed structure on the subject allotment is not attached to a building required to conform with this Standard, that structure shall conform with the construction requirements of this Standard.

 

Alternatively, the adjacent structure shall be separated from the subject building by one of the following:

(a) A distance of not less than 6m from the building required to conform with this Standard. This distance is measured as any of the horizontal straight lines from the adjacent structure to the subject building.
or,

(b) A wall of the building required to conform that extends to the underside of a non-combustible roof covering and has an FRL of not less than 60/60/60 for load bearing walls and -/60/60 for non-load bearing walls when tested from the outside. Any openings in the wall shall be protected in accordance with the following:

 

• (i) Doorways - By self-closing fire doors with an FRL of -/60/30, conforming with AS1905.1 and tested in accordance with AS 1530.4.

• (ii) Windows - By fire windows with an FRL of -/60/- when tested in accordance with AS1530.4 and permanently fixed in the closed position.

• (iii) Other openings - By construction with an FRL of not less than -/60/- when tested in accordance with AS1530.4.

• Note: Control and construction joints, subfloor vents, weepholes and penetrations for pipes and conduits need not conform with Item (iii).

 

or,

(c) A wall of the building required to conform that extends to the underside of a non-combustible roof covering and is of masonry, earth or masonry-veneer construction with the masonry leaf of not less than 90mm in thickness. Any openings in the wall shall be protected in accordance with the following:

 

• (i) Doorways - By self-closing fire doors with an FRL of -/60/30, conforming with AS1905.1 and tested in accordance with AS 1530.4.

• (ii) Windows - By fire windows with an FRL of -/60/- when tested in accordance with AS1530.4 and permanently fixed in the closed position.

• (iii) Other openings - By construction with an FRL of not less than -/60/- when tested in accordance with AS1530.4.

• Note: Control and construction joints, subfloor vents, weepholes and penetrations for pipes and conduits need not conform with Item (iii).

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External Mouldings (Clause 3.3)

Unless otherwise required in Clause 3.6.1 and Sections 5 to 9, combustible external mouldings, jointing strips, trims and sealants may be used for decorative purposes or to cover joints between sheeting.

 

 

Higher Levels of Construction (Clause 3.4)

A higher level of BAL construction can be used in lower level of BAL Construction (ie: if your building is BAL 29 for example, construction complying with BAL 40 or BAL FZ is acceptable).

 

 

Reduction in Construction Requirements due to Shielding (Clause 3.5)

The Relevant Building Surveyor (RBS) may be able to grant a reduction to the next lower BAL to a wall that is not exposed to the bushfire threat (see AS3959:2018 for further information and diagrams). This does not apply to floors, roofs or walls exposed to the bushfire threat.

 

 

Vents, Weepholes, Gaps and Screening Materials (Clause 3.6)

- Vents, Weepholes, Joints and the like.

All gaps including vents, weepholes and the like shall be screened, except for weepholes to the sills of windows and doors. All joints shall be suitably backed with a breathable sarking or mesh, except as permitted by Clause 3.3. The maximum allowable aperture size of any mesh or perforated material used as a screen shall be 2mm.

 

- Gaps to door and window openings.

Where screens are fitted to door openings for ember protection, they shall have a maximum aperture of 2mm and be tight fitting to the frame in the closed position.

Gaps between doors including jambs, heads or sills (thresholds) shall be protected using draught seals and excluders or the like (see AS3959:2018 Figure 3.2).

 

Windows conforming with AS2047 will satisfy the requirements for gap protection.

Screens fitted to window openings (insect screens with ember mesh) shall have a maximum aperture of 2mm and these shall be tight fitting to the frames.

 

 

Bushfire Shutters (Clause 3.7)

Refer to AS3959:2018 for requirements of bushfire shutters if they are being provided.

If bushfire shutters are fitted to all external doors then at least one of those shutters shall be operable from the inside to facilitate safe egress from the building.

 

 

Testing of Materials, Elements of Construction and Systems to the AS 1530.8 series (Clause 3.8)

Refer to AS3959:2018 for requirements details on AS1530.8 series.

Where any element of construction or system satisfies the test criteria in the AS1530.8 series without screening for ember protection, the requirements of this Standard for screening of openable parts of windows shall still apply.

 

Where a window protected with a shutter satisfies the test criteria of the AS1530.8 series, the additional requirements of this Standard for screening of openable parts of windows do not apply.

 

 

Glazing (Clause 3.9)

Glazing requirements shall be in accordance with Sections 5 to 9 of this Standard.

 

 

Sarking (Clause 3.10)

Where sarking is required in Sections 5 to 9, the flammability index shall not be greater than 5 when tested in accordance with AS1530.2.

 

 

Timber Log Walls (Clause 3.11)

Where the thickness of a timber log wall is specified in Sections 5, 6 and 7, two criteria are nominated, as follows:

(a) The nominal overall thickness is the overall thickness of the wall.

(b) The minimum thickness is the thickness of the wall at the interface of two logs in the wall.

Note: For most log profiles, the thickness of the log at the interface with an adjacent log is less than the overall thickness of the wall.