Landscape and Building Design for Bushfire Areas

Caird Ramsay, Lisle Rudolph

• Publisher: CSIRO PUBLISHING
• Year: 2003
• Print ISBN: 9780643069046
• eBook ISBN: 9780643098817
• Topic: Technology & Engineering
• Subtopic: Urban Planning & Landscaping
• Index: Technology & Engineering

Shortlisted in TAFE Vocational Education category in the 2004 Australian Awards for Excellence in Educational Publishing.

The devastation wreaked by bushfires on Australian homes and landscapes is an all too familiar scenario. Yet, why do we often see one house burn, whilst an apparently similar house on an adjacent block can endure? Research has shown that many factors affect the chances of a building surviving a bushfire. If you are designing landscapes and buildings in bushfire areas you need to be aware of these factors so that the chances of losses to life and property can be minimised.

Landscape & Building Design for Bushfire Areas integrates the latest scientific knowledge about buildings and bushfires with a flexible design approach.

The book contains two main sections:
1) Provides a clear description of what happens in a bushfire. It describes the environment in which bushfires occur, how a fire attacks, and how buildings are ignited and destroyed.
2) Sets out a practical design approach to the design of buildings and their immediate surroundings. It presents a range of options for designing the various elements of both landscapes and buildings in bushfire-prone areas.

This book encourages design for bushfire to be included as a normal part of designing in bushfire-prone areas, rather than as an undesirable add-on. It will assist planning and building regulatory authorities to improve and administer regulatory requirements and guidelines.

Section two

Designing for
bushfire areas

This section describes a method for designing landscapes and buildings to overcome the problems of living in a bushfire area. It presents a range of options to assist in the design of the most important elements of landscapes and buildings.

Chapter 5: Design – general

This chapter explains the general method for designing landscapes and buildings. The chapters that follow give specific guidelines for the landscape and for buildings.

Priorities for design

It is unlikely that anyone would start designing their property with bushfire survival as their first priority because surviving a bushfire is not the main reason why people build. Hazards are problems that people would rather not have to think about and removing them does not give any positive enjoyment other than perhaps peace of mind. Nevertheless, the penalties for ignoring the risk of bushfire in hazardous areas can be severe.

In the final analysis, design for bushfire can never be treated in isolation from all other requirements. Buildings and their surrounding landscaping should satisfy many requirements including human comfort and satisfaction, social, economic and environmental criteria, to mention just a few. Undue emphasis on the bushfire aspects would distract attention away from other fundamental requirements. Successful design for bushfire will only be achieved if it is seen as part of the wider context.

The aim of this manual is to help people to include design for bushfire along with all of their objectives rather than as something added on afterwards. The key to integration of any objective is to include it early in the design process. If this is not done, it may be disruptive and expensive later when all of the other objectives have been dealt with.

If bushfire objectives are acknowledged early in the process the design of buildings for bushfire need not necessarily compromise other objectives or lead to expensive or unconventional buildings.

Design for bushfire survival applies not only to new buildings, but includes the modification of buildings and their surroundings over the whole of their lifetime. Therefore designing for bushfire is done by all those involved in that ongoing process, not just the design professionals.

Design options

In all designing, there is hardly ever a situation in which there is not more than one way of achieving an objective or solving a problem. The process of designing is not just a sequence of irreversible decisions taken one after another. A designer usually goes back and forth, trading off different options until a suitable solution is achieved.

The approach taken in this manual is to state objectives first and then provide design options for meeting them. These options are based on design principles which have been derived from a consideration of how to combat each of the modes of attack which have been described in Chapter 3, ‘Ignition and destruction of buildings’. This approach offers designers the flexibility they need to meet their individual situations and is better than giving them a straight list of ‘do’s’ and ‘don’ts’. If designers understand what each objective is, they can choose the option or combination of options that suits them best.

Ready made bushfire house designs

Both single-concept and ready-made bushfire house designs cannot be generally applied. In the case of single-concept solutions, such as building underground or relying on roof-top sprinklers, weak links will remain and a combination of design options is needed.

Off-the-rack bushfire house designs are not readily adaptable to different lots and may include excessive or expensive features that are not appropriate for a given situation. Model display bushfire houses have contained such features in the past and may actually discourage people from designing for bushfire because they are restrictive. Furthermore the focussing of attention on the building as the means of improving the chances of survival will deflect thought away from what can also be achieved by the use of siting and landscaping. In fact, exploiting the assets of the landscape to provide some degree of protection and also modifying some undesirable aspects of it offers many opportunities to reduce destruction of buildings in a very cost-effective manner.

Conflicting objectives

When bushfire design objectives conflict with other objectives, it is usually possible to trade off options between them. For example, someone may have a desire to have very large windows to capture a view and to allow sunshine to penetrate. These windows could be a serious weakness in a bushfire because they could be cracked by heat radiation or broken by wind-blown objects thus allowing embers to enter. There are various options, some of which may be used together, to resolve the conflict. For example, the designer could:

• use special glass resistant to breaking (e.g. toughened glass),

• reduce the size of panes of glass to increase strength,

• use metal shutters externally (e.g. sliding, hinged or rolling vertically),

• avoid locating combustible structures (e.g. pergolas) close to the windows,

• avoid locating highly flammable vegetation close to the windows, and

• protect the windows externally with plants that are suitable for forming a barrier against wind, embers, burning debris and radiation.

Landscape and building approaches

The first four options listed in the example given for the protection of large windows involve the building itself, whereas the remainder require modification of the landscape. All of the design options that can be taken to improve the chances of survival of a building in a bushfire can be classified under two main approaches:

• the landscape approach, and

• the building approach.

The landscape approach consists of choosing a suitable lot and landscaping the surroundings of the building to reduce the attack of a bushfire and the wind on the building.

The building approach consists of designing the building so that it does not ignite readily when subjected to the attack of a bushfire and the wind.

Either the landscape or th...

Table of contents

• Cover
• Title
• Copyright
• Contents
• Foreword
• Acknowledgements
• Section one: What happens in a bushfire?
• Section two: Designing for bushfire areas
• Glossary
• References and further reading
• Index