BAL Levels and Weephole Requirements

Bushfire Attack Levels in AS3959:2018

BAL - Low 
There is insufficient risk to warrant specific construction requirements.
BAL - 12.5 
Ember attack and radiant heat up to 12.5kW/m2.
BAL - 19 
Increasing levels of ember attack and burning debris ignited by wind-borne embers together with increasing radiant heat greater than 12.5 kW/m2 up to and including 19 kW/m2. 
BAL - 29 
Increasing levels of ember attack and burning debris ignited by wind-borne embers together with increasing radiant heat greater than 19 kW/m2 up to and including 29 kW/m2. 
BAL - 40 
Increasing levels of ember attack and burning debris ignited by wind-borne embers together with increasing radiant heat greater than 29 kW/m2 up to and including 40 kW/m2. 
BAL - FZ 
Direct exposure to flames together with ember attack and radiant heat of more than 40 kW/m2. 
Construction in BAL—FZ may require reliance on measures other than construction. The requirements for construction of a building BAL—FZ may be regulated by the building authorities having jurisdiction in the States and Territories of Australia.

Summary of Weep Hole Requirements in AS3959:2018

BAL - Low
The Bushfire Attack Level BAL—LOW is based on insufficient risk to warrant specific bushfire construction requirements. It is predicated on low threat vegetation and non- vegetated areas (see Clause 2.2.3.2).
BAL - 12.5 
Clause 5.4.3  "Except for exclusions provided in Clause 3.6, vents and weepholes in external walls shall be screened with a mesh (maximum aperture 2mm) made of corrosion-resistant steel, bronze or aluminium."
BAL - 19
Clause 6.4.3  "Except for exclusions provided in Clause 3.6, vents and weepholes in external walls shall be screened with a mesh (maximum aperture 2mm) made of corrosion-resistant steel, bronze or aluminium."
BAL - 29
Clause 7.4.3  "Except for exclusions provided in Clause 3.6, vents and weepholes in external walls shall be screened with a mesh (maximum aperture 2mm) made of corrosion-resistant steel, bronze or aluminium."
BAL - 40
Clause 8.4.3 "Except for exclusions provided in Clause 3.6, vents and weepholes in external walls shall be screened with a mesh (maximum aperture 2mm) made of corrosion-resistant steel, bronze or aluminium." 
BAL - FZ
Clause 9.4.3 "Except for exclusions provided in Clause 3.6, vents and weepholes in external walls shall be screened with a mesh (maximum aperture 2mm) made of corrosion-resistant steel or bronze"

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The Weepa range is subject to Intellectual Property Rights. Aust Pat Nos 713335, 762230, 2007237177, 2007215369, 2008271915, 2013211506. Aust Pat Aps 2018902177, 2019900971. International PCT AU2007/000004, PCT AU2014/000123, PCT AU2019/050629. NZ Pat No 567674. NZ Pat Ap 716834. Sth African Pat No 2008/03841. US Pat Nos 8171677, 14/908620. Canadian Pat Nos 2629033,2916320.UK Pat No1984580.Des Reg137021,150609,156915.Aust TM 775282,NZ TM 961710,US TM 1145302.