Section 8 - AS 3959:2018

Construction Requirements for BAL 40

Five houses in the path of a bushfire, demonstrating the different bushfire attack levels that houses can be subject to

BAL 12.5

Sections 3 & 5

Ember attack

radiant heat

below 12.5kW/m2.

BAL 19

Sections 3 & 6

Increasing ember attack and windborne debris, radiant heat between 12.5kW/m2

and 19kW/m2.

BAL 29

Sections 3 & 7

Increasing ember attack and windborne debris, radiant heat between 19kW/m2

and 29kW/m2.

BAL 40

Sections 3 & 8

Increasing ember attack and windborne debris, radiant heat between 29kW/m2

and 40kW/m2. Exposure to flames

from a fire front likely.

BAL FZ

Sections 3 & 9

Direct exposure to flames, radiant heat and embers from

the fire front.

Section 8 - AS 3959:2018

BAL 40 Reference Guide

Refer to Sections 3 & 8 for all BAL 40 Requirements

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 (including Amendments 1 & 2), AS1530.8.1, AS1530.8.2 and official test reports and assessments.

BAL 40

General

(Clause 8.1)

A building assessed as being BAL 40 shall conform with Section 3 (General Construction Requirements) and Clauses 8.2 to 8.8 of AS3959:2018.

Any element of construction or system that satisfies the test criteria of AS1530.8.1 may be used in lieu of the applicable requirements contained within Clauses 8.2 to 8.8 (see Clause 3.8).

BAL 40

Subfloor Supports

(Clause 8.2)

- Unenclosed Subfloors.

Supports (stumps, etc.) shall be (a) non-combustible, or (b) a system conforming with AS1530.8.1.

- Enclosed Subfloors.

No requirements if the subfloor is enclosed with a cladding that conforms with the wall requirements (sarking not required behind subfloor cladding).

BAL 40

Floors

(Clause 8.3)

- Unenclosed Subfloors.

Bearers and joists shall be (a) non-combustible, or (b) have the underside of the combustible elements of the floor system protected with non-combustible material (eg, cement sheet or metal sheet), or (c) a system conforming with AS1530.8.1.

- Enclosed Subfloors.

No requirements if the subfloor is enclosed with a cladding that conforms with the wall requirements (sarking is not required behind the subfloor cladding).

BAL 40

Walls

(Clause 8.4)

Walls shall be (a) non-combustible (including brick, concrete, rammed earth and mud brick, etc. at min. thickness of 90mm), or (b) cladding on sarked walls that is (i) non-combustible, or (ii) min 9mm thick cement sheet, or (iii) steel, or (c) a system conforming with AS1530.8.1.

Any gaps greater than 2mm to be screened with 2mm mesh in corrosive resistant steel, bronze or aluminium.

BAL 40

Windows, Sidelights & Doors

(Clause 8.5)

This section of AS3959:2018 includes multiple compliance paths and detailed variations. Always confirm exact requirements using the current version of AS3959.

* Compliance options for BAL 40 windows and doors.

(a) A system tested to conform with AS1530.8.1, or

(b) Be completely protected by a bushfire shutter, or

(a) System Tested to AS1530.8.1.

Window and door manufactures can have their products tested to comply with a BAL rating. Refer to window and door manufacturers for options.

Note: Non-combustible frames are usually the only option for BAL 40, however tested timber windows and doors are available from Paarhammer.

(b) Bushfire Shutters.

Bushfire shutters can be used to protect windows and doors that are not:

(a) tested to AS1530.8.1, or

(b) do not meet the DTS requirements.

Where fitted, they must conform with Clause 3.7 and be made from non-combustible material.

- DTS Frames.

Window and door frames shall be metal (inc. aluminium).

- DTS Glazing.

For windows, sidelights and doors, toughened glass with a min. thickness of 6mm.

- DTS external glass protection information.

All DTS glazing is to be protected by externally fitted screens (glazing protection screens) made from (a) metal, or (b) a tested system to AS1530.8.1, and have 2mm mesh or perforated sheet in (a) corrosive resistant steel, or (b) bronze (no aluminium allowed).

For the DTS window option, screens (glazing protection screens) must cover the glazing, and must prevent embers from entering an open window, the use of two screens may be needed in certain cases (see insect/ember screen info below).

For the DTS door option, screens (glazing protection screens) must protect the glazing by either screen doors or screens fixed to the face of the openable door to protect glazing (seperate insect/ember screen doors are not a requirement).

* Understanding the term 'Screens' in AS3959:2018.

The term, 'screen' in this section is used to describe three different applications:

1. Complete Screening.

Screens need to be applied externally to cover the entire window or door assembly, including the frame, glazing, sash, sill and hardware. This gives maximum protection from embers and radiant heat.

2. Glazing Protection Screens.

Only the glass area is protected by screens. These are fitted externally and reduce radiant heat exposure to glazing. This could be done by fixing the screening to the window and/or door frame, or using an external insect/ember screen door.

3. Insect/Ember Screens.

These are required on openable windows and may be fitted internally or externally to prevent ember entry when the windows are open. These are required for openable windows at all Bushfire Attack Levels. Doors do not require these, but if fitted externally, need to comply with the screening material for each Bushfire Attack Level.

* BAL 40 Screening Material.

All screens must be made from mesh or perforated sheet (max. 2mm aperture) using:

(a) corrosive resistant steel, or

(b) bronze. (aluminium is not allowed)

Refer to AS3959:2018 for frame requirements.

BAL 40

Garage Doors

(Clause 8.5.6)

Garage doors shall be (a) non-combustible, or (b) bushfire resisting timber, or (c) 6mm cement sheet, and requires door seals to meet section 3 of AS3959:2018.

BAL 40

Roofs

(Clause 8.6)

- General.

Any roofing materials, systems or accessories shall be (a) non-combustible, and (b) sealed in accordance with AS3959:2018 Clause 3.6, and (c) any roof vents fitted with ember guards with 2mm mesh or perforated sheet in corrosive resistant steel or bronze (no aluminium allowed).

- Evaporative coolers.

Evaporative coolers are not permitted.

- Fascias & Eaves (including alfresco ceilings)

Fascias & bargeboards shall conform with AS1530.8.1.

Eave lining shall be min. 6mm thick cement sheet.

Note: for alfresco ceilings, standard plasterboard is non-compliant at BAL 40.

Fascias and eave gaps to be fitted with 2mm mesh or perforated sheet in corrosive resistant steel or bronze (no aluminium allowed).

- Tiled Roofs.

Tiled roofs to be fully sarked and shall (a) be located on top of roof framing, except battens may be fixed above the sarking, and (b) cover the entire roof, inc ridges and hips, and (c) extend into gutters and valleys.

- Sheet Roofs.

Sheet roofs to be fully sarked and shall (a) be located on top of roof framing, except battens may be fixed above the sarking or foil backed insulation blankets may be installed over the battens, and (b) cover the entire roof, inc ridges and hips, and (c) extend into gutters and valleys, and (d) have any gaps sealed at the fascia or wall line, hips and ridges by (i) 2mm mesh or perforated sheet in corrosive resistant steel or bronze (no aluminium allowed), or (ii) mineral wool, or (iii) other non-combustible material.

- Verandah & Carport Roofs.

Verandah and carport roofs shall meet the roof requirements of the main roof, or be separated by an external wall conforming with the wall requirements and shall have non-combustible roof covering, and the complete support structure shall be (a) non-combustible material, or (b) timber rafters lined on the underside with min. 6mm cement sheet or material conforming with AS1530.8.1, or (c) a system conforming to AS1530.8.1.

- Downpipes & Gutters.

No requirement for downpipes.

Gutters shall be non-combustible.

Box gutters shall be non-combustible, and flashed with non-combustible materials.

- Gutter Guards.

No requirement to install gutter or valley guards, but if they are fitted shall be non-combustible.

- Skylights.

Refer to AS3959:2018 for requirements of skylight flashing and glazing.

- Roof Penetrations.

Refer to AS3959:2018 for requirements of roof penetrations such as skylights, evaporative coolers, vent pipes, aerials and support brackets, etc as there are many.

BAL 40

Verandahs, Decks, Steps & Landings

(Clause 8.7)

- Verandah & Carport Posts.

Verandah and carport posts shall be non-combustible.

- Unenclosed Deck Supports & Framing.

Deck supports and framing shall be (a) non-combustible, or (b) a system conforming to AS1530.8.1.

- Enclosed Deck Supports & Framing.

If the subfloor is enclosed, it must be enclosed to match the wall requirements, and there are no requirements for the supports and framing.

- Decking Boards, Stairs & Ramps.

Decking boards, stair treads, landings and ramps shall be (a) non-combustible, or (b) cement sheet, or (c) a system conforming to AS1530.8.1.

- Balustrades.

Balustrades, handrails and other barriers within 125mm of any glazing or combustible wall, shall be non-combustible.

BAL 40

Water & Gas Pipes

(Clause 8.8)

Above ground exposed water supply pipes shall be metal, external gas pipes and fittings above ground shall be of steel or copper with a min. wall thickness in accordance with gas regulations or 0.9mm, whichever is the greater and shall extend a min. of 400mm within the building and 100mm below ground.