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Building in a fire zone - Risks and impacts on the Northern Beaches

With its long stretch of beaches, you'd be forgiven for thinking the Northern Beaches doesn't have any bushfire risk. But in actual fact a large portion of the LGA is covered in bush and many homes fall into bushfire risk zones.

Building a property in a bushfire zone comes with a unique set of requirements that can push up building costs and build times.

In this article, Catherine Ryland from CR Bushfire explains the risks and implications of building in a bushfire zone depending on the level of threat. Find out how it will affect your build, how much it will cost and when you should order a bushfire report if you're shopping for property on the Beaches.

Why should home buyers assess bushfire risk when shopping for a property on the Northern Beaches?

The Northern Beaches is actually quite prone to bushfires, with several exposed regions carrying significant risk. Home buyers should always check the bushfire prone land map to determine if the property or its vegetation falls within the bushfire prone area or its buffer zone.

If it is mapped as bushfire prone, it is advisable to engage a bushfire consultant to understand the potential risks. This information is crucial especially if there are plans for renovations or construction in the future.

The costs associated with building in areas with higher bushfire attack levels, particularly in Flame Zone, can be significant and may even make it unfeasible. Additionally, certain types of development may be restricted in bushfire prone areas. Engaging a consultant upfront will provide valuable information and help avoid unforeseen challenges and expenses that could arise later on.

Where are the main bushfire risk areas on the Northern Beaches?

The primary bushfire risk in this region originates from the national parks, such as Garigal and Ku-ring-gai Chase, situated in the northern and western parts. These parks encompass extensive stretches of vegetation, presenting significant risks. Communities around Belrose, Davidson, and Frenchs Forest, which are adjacent to these parks, are well aware of the bushfire risks in their vicinity.

There are also unexpected locations where bushfire risks exist, particularly in the northern part of the peninsula around Bilgola and Avalon. These areas have smaller reserves, some of which are managed and utilised for activities like mountain biking and recreation. Despite their size, these reserves still carry bushfire risk, and proper assessment needs to be conducted.

Some houses located near these reserves, in close proximity to the vegetation, are mapped as bushfire-prone areas and may even fall into the flame zone, despite the perceived lower risk. This can be surprising to residents.

How is the process different for building a house in a bushfire-prone area compared to an unaffected zone?

The construction requirements for houses in bushfire-prone areas are determined by the specific bushfire attack level, with the level of protection increasing as the potential impact of the bushfire rises.

There are six different bushfire attack levels. One of them is BAL Low, which indicates that no specific bushfire protection measures are required. The remaining five BAL levels are based on radiant heat levels. BAL 12.5 is the lowest level, corresponding to a radiant heat level of 12.5 kilowatts per meter squared. The levels then increase progressively, reaching BAL 19, 29, 40 and, the highest level which is known as Flame Zone.

The impact on your renovation or build depends on the level you are in. For example, at lower levels like 12.5 BAL, the focus is on protecting against ember attacks. This involves specific measures such as using corrosion-resistant metal fly screens with a tight mesh.

Ensuring all gaps are sealed is also important, including vents and gaps around doors. The thickness of glazing increases with higher bushfire attack levels.

As we reach the Flame Zone, additional measures come into play. This includes the requirement for bushfire shutters on windows and a roof system that complies with construction standards for Flame Zone. These measures can be quite expensive.

If you're renovating an older house in a bushfire-prone area, would you be required to fix other parts of the house due to stricter building standards?

The general rule of thumb is that if your renovation involves increasing the floor space by more than 50% of the existing floor space, then you would be required to upgrade the rest of the dwelling for ember protection.

It's important to note that we don't apply bushfire attack levels to existing legacy development as it would be impractical and costly. Instead, we focus on upgrading the existing parts of the dwelling to improve ember protection.

This typically involves applying fly screens, closing gaps, and adding mesh to openings if necessary to prevent ember penetration. Additionally, draft excluders may be used on doors, and garage doors may have ember-resistant rollers installed. The goal is to ensure the building has no openings or holes through which embers can enter.

Can you go through a Complying Development if you’re in a bushfire zone or do you have to do a DA?

There is a compliance threshold for development, which applies state-wide, that means you cannot do a complying development in areas with a bushfire attack level of 40 or flame zone. Any area with a bushfire attack level of 29 or lower is suitable for complying development.

If the project is below this level, all that is required from a bushfire consultant is a BAL Certificate, which certifies that the development is not in a bushfire attack level 40 or flame zone.

However, if a development application (DA) needs to be submitted to the council, a more comprehensive report called a bushfire assessment report or bushfire hazard report is necessary.

This report not only calculates the BAL rating, but also assesses other measures outlined in the "Planning for Bushfire Protection" book published by the Rural Fire Service. These additional measures include determining the required asset protection zone, managing the surrounding landscaping, assessing water supply, access, and utilities.

How is landscaping affected by bushfire zoning?

Landscaping plays a crucial role in bushfire protection, particularly on private lots. It involves creating an asset protection zone or inner protection area around the house to prevent the easy movement of fire from the surrounding landscape into the property. The goal is to avoid the formation of a fire path that could lead directly to the house and potentially result in its destruction.

In a forested area, different levels of vegetation structure exist, including the understory, mid-story, and canopy. To impede the progress of fire, certain elements of this structure need to be removed or modified.

For instance, if two shrubs are situated close to each other, fire can easily spread from one shrub to another. By removing specific elements along this pathway, such as shrubs or thinning out the canopy, we can inhibit the easy movement of fire toward the property.


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