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Bushfire Protection Issues

Disclaimer

This section is revised from time to time.
It is developed from experience in this architectural practice and associated activities of allied organisations.
It is intended to be an evolving discussion topic with thinking and understanding extending over time.
This section does not attempt to reflect in any particular way any specific expertise, standards, or attitudes held by any bushfire organisations or regulatory instrumentalities.

Layout

This section embodies the following discussion topics:-

Philosophy

Consistent with ESD principles, this architectural practice seeks to fulfill reasonable bushfire protection objectives, while also meeting the broader environment protection goals.
Within this philosophy, the preservation of human life takes highest priority; protection of property less so.
As well this philosophy seeks to achieve protection of natural systems from the impact of excessive implementation of conventional bushfire techniques, notably vegetation clearance, by incorporating more advanced bushfire mitigation and protection techniques.

broad area assessment

The philosophy requires that the broader context of development proposals is considered. Thus the topography, geology and variety of vegetations are considered together with priority fire wind directions, extreme weather potential and applicable fire behaviour; rather than a simplistic generic view of fire propagation within a limited model of fire behaviours.

local area assessment

The philosophy accepts that local vegetation within the site can contribute to local fire behaviour differing from the broad area; vegetation with appropriate density characteristics or wetted by an on-site waste water re-use system can contribute to fire barrier rather than be considered part of the fire fuel load.

building features assessment

The philosophy considers the development infrastructure within and around the building which can contribute to fire protection, including conventional contributions including vegetation and landform modifications, and internal fire refuges.

occupant behaviour

The philosophy accepts that occupant behaviour has a major role to play in achieved bushfire protection, including both conventional considerations of vegetation, fuel load management and fire fighting facility maintenance, and management introduced by this practice to occupants such as evacuation kit and plan which form part of the self sufficiency manual information.

Standard building features

Consistent with the Building Code of Australia Section SA G5.101, the projects of this practice embody these bushfire resistant construction practices.
The Section advises:-
- floor systems with concrete-on-ground or protected under floor surfaces or voids
- wall systems which are non-combustible, contain fire retardant sarking, or timber logs with no ember or spark paths
- windows and doors with draught seals and metal flyscreen covering
- roofs non combustible and avoiding ember or spark entry at flashings, gutters, eaves.
- vertical skylights with wired glass.
- services pipes buried or metal construction
and other detail construction.

Standard bushfire asssessment

At this time no input to this section of this web site has been possible, because this architect has not been able to overview the assessment philosophy, standards or process of the S.A. Country Fire Service - Bushfire Protection Unit.

Conventional infrastructure

In South Australia, the Native Vegetation Council considers applications for clearance of natural vegetation in defined regions as a control measure against excessive land clearing.
The Native Vegetation Act provides for a dispensation for vegetation within 20metres of approved development as part of bushfire protection measures.
S.A. Country Fire Service - Bushfire Protection Unit sometimes recommends clearances beyond these distances in their assessment.

Consistent with these techniques as well as the Building Code requirements, projects from this practice regularly incorporate some vegetation clearance in the prominent fire path directions, as well as non combustible external materials and finishes as well as compartmentation of the building interior. Steel roof decks, autoclave concrete, stone, rammed earth exteriors and segregation of living spaces from private spaces into fire isolated zones with non combustible separating walls are common solutions.

Unique solutions

This practice has developed a number of projects in bushfire locations consistent with locating habitation in connection with land protection and revegetation projects. As vegetation retention is consistent with ESD principles which are described throughout this web site; interactions between vegetation value and bushfire protection are a regular issue in project design from this practice. In addition to incorporating standard features, the projects additionally utilise one off solutions developed to be suited to each situation. These features include:
  • segregated non combustible wall structure and main structure
  • fire refuge
  • earth berme
  • curved roof
  • fire rated shutters

segregated non combustible wall structure and main structure

This practice has evolved and implemented on a number of projects construction utilising steel main structure set within the non combustible and fire rated external skin of the building to achieve fire resistant construction standards beyond those required as noted above.

fire refuge

The design of a number of projects incorporate internal fire refuge potential beyond the compartmentation of the building. Usually this is a wet area with no flammable surfaces or finishes incorporating also metal fire window shutter, smoke seals to openings and a hose reel within the space for active fire intrusion control.

earth berme

Some projects contains earth berme either against the building exterior to add to the building fire heat resistance, or as part of landform modification to form a fire deflection mound in the prominent upwind direction from the building.

curved roof

Curved roof form is used in concert with landform modification to maximise the effectiveness of the deflection strategy.

fire rated shutters

In conjunction with earth berme or fire refuge, fire rated shutters emenating from their use in commercial building interior shaft protection to Metropolitan Fire Service requirements are used in bushfire protection to achieve performance beyond conventional construction standards.

Projects

Projects implemented from this practice include:-

projects embodying standard bushfire features:
- Uniting Church residential colony, Kuipto
- Addition to Driffield Ct house, Bridgewater
- Addition to Silver Sands residence
- Addition to Lopresto residence, Coromandel Valley
- Addition to Ashton residence
- multiple residences for Leonard family, Callington
- Kameruka residence, Inman Valley
- Redcone residence, Bower
- Klopsch Road cottage, Lobethal
- proposal for Coach House Drive residence, Teringie
- proposal for Stevens residence, Vivonne Bay, Kangaroo Ils.

projects embodying both standard and unique features:
- Dolbat - D'Estrees Bay, Kangaroo Ils.
- Martin residence, Carey Gully
- Strathearn residence, Wistow
- proposal for St.John residence, Carey Gully
- proposal for Davelea residence, Kuitpo

Dolbat - D'Estrees Bay, Kangaroo Ils.

The building is set into the sloping landform to create a berme toward the fire prone direction, the building has internal steel frame and partial external stone walling, steel roof, bathroom fire refuge

Martin residence, Carey Gully

The building is of stone construction with steel roof with excavated open ground and deflection mound toward the fire prone direction,

Strathearn residence, Wistow

The building has interior steel frame and external partial stone cladding. The bathroom is set within the building volume separating living and bedroom functions with direct external path to the egress from the site shielded by the greenhouse and garage wings of this Y shaped building.

proposal for St.John residence, Carey Gully

This proposal is for an extreme bushfire site in unbroken native vegetation within the site and beyond in the undulating sloping land in the fire prone direction. The design has separate interior steel structure and 4 hour fire rated autoclave concrete external skin complete with earth bermes and fire rated shutters, steel curved roof deck, fire refuge bathroom, and compartmention.

proposal for Davelea residence, Kuitpo

The proposal is for a building set in a native bushland site with farmland area surrounding. The proposal includes clearing extension around the building, separate internal steel structure, external 4 hour fire rated autoclave concrete skin, some berme arising from the lower level of the building set into the slope, laminated glass to openings, steel roofs, some compartmention between living, bedroom and garaging sections of the building. The subsidence tower is expected to contribute to avoiding ember intrusion into the building.

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