BAL FZ Gutter Guard Requirements: A Guide to AS3959 Compliance

BAL-FZ is Australia’s highest Bushfire Attack Level. A building assessed as Flame Zone may be exposed to severe ember attack, burning debris, high radiant heat and direct flames from a potential fire front.

That makes material selection and construction detailing particularly important. However, the BAL-FZ gutter guard requirements are often misrepresented online. A non-combustible gutter leaf guard is not automatically the same thing as an ember guard protecting a roof opening, and a mesh aperture below 2mm does not by itself make an entire installation BAL-FZ compliant.

This guide explains what property owners, builders and specifiers need to distinguish when selecting gutter protection for a BAL-FZ project. It covers non-combustible gutter guards, ember-guard mesh, roof-profile compatibility, installation, maintenance access and the limits of aluminium Fine Mesh in a project requiring Flame Zone construction.

What Is BAL-FZ?

BAL stands for Bushfire Attack Level. It is used to classify the potential severity of bushfire exposure at a building site.

The assessment considers potential exposure to:

• Ember attack
• Burning debris
• Radiant heat
• Direct flame contact

The BAL categories are:

• BAL-LOW
• BAL-12.5
• BAL-19
• BAL-29
• BAL-40
• BAL-FZ

BAL-FZ, or Flame Zone, is the highest category. NSW Rural Fire Service describes it as an extreme risk involving direct exposure to the flames of a potential fire front.

You can review the NSW Rural Fire Service BAL guidance for a general explanation of the risk categories.

BAL-FZ Is More Than an Ember-Risk Classification

Ember protection remains important at BAL-FZ, but the project must also address the possibility of severe radiant heat and direct flame contact.

This means a product should not be marketed as a complete BAL-FZ solution merely because it is:

• Made from metal
• Non-combustible
• Fire tested
• Fitted with a mesh aperture below 2mm

Those characteristics may be relevant to a particular construction requirement, but BAL-FZ applies to the complete building design and its documented construction details.

Which Standard Applies?

AS 3959:2018 — Construction of buildings in bushfire-prone areas is the primary Australian standard dealing with bushfire construction requirements.

At the time of writing, the 2018 edition remains published. Standards Australia has advised that a revision is progressing through its standards-development process.

Depending on the property and work, the project may also be affected by:

• The National Construction Code
• Applicable amendments to AS 3959
• State or territory building regulations
• Local planning requirements
• Bushfire overlays or mapped bushfire-prone areas
• A project-specific BAL assessment
• A Bushfire Attack Level report
• A bushfire management plan
• Alternative-solution or performance-solution documentation
• Product test reports and certification

Use the Approved Project Documents

The applicable BAL report and approved construction documents should determine the required materials and installation details.

A generic online guide cannot override:

• The building approval
• The certifier’s requirements
• The bushfire consultant’s specification
• The architect’s documented details
• The relevant clauses of AS 3959
• Applicable product limitations

Where a proposed gutter guard differs from the documented construction, obtain written confirmation before ordering or installing it.

Gutter Guards vs Ember Guards

This distinction is central to understanding the BAL-FZ gutter guard requirements.

Gutter or Valley Leaf Guard

A gutter or valley leaf guard is installed primarily to help reduce leaves, twigs and other larger debris accumulating in the drainage system.

It may also help reduce combustible organic material collecting inside the gutter, but its primary physical function is debris management.

Ember Guard

An ember guard is mesh, perforated sheet or another approved construction used to help restrict ember entry through a specified opening or gap.

Examples may include protection for:

• Roof ventilation openings
• Wall vents
• Weepholes
• Openable window or door screens
• Gaps beneath roof sheets
• Other openings identified in the applicable construction provisions

One Product May Perform Different Functions

Fine metal mesh may sometimes be used as both a gutter leaf guard and an ember guard. However, that does not mean every gutter guard automatically performs both functions.

Whether it can serve as an ember guard depends on:

• Mesh aperture
• Mesh material
• The BAL category
• The opening being protected
• The supporting frame or fixing components
• The perimeter gaps
• The applicable AS 3959 provision
• The approved installation detail

The phrase “BAL-FZ gutter guard” should therefore be used carefully. It may refer to a non-combustible leaf guard installed on a BAL-FZ building, but it does not necessarily mean that the same aluminium mesh is an approved BAL-FZ ember guard for every opening.

Are Gutter Guards Mandatory at BAL-FZ?

Gutter and valley leaf guards are not universally mandatory merely because a property has a BAL-FZ classification.

Official bushfire guidance commonly uses wording such as:

Where installed, gutter and valley leaf guards are to be non-combustible.

This means the standard distinguishes between:

• Whether a gutter guard is installed
• What it must be made from when it is installed
• Separate ember-protection requirements for openings and roof gaps

However, a project’s approved plans or bushfire report may expressly require gutter protection. In that situation, it becomes a project requirement even where the general standard does not universally require every building to have gutter mesh.

Why Metal Gutter Guards Are Still Commonly Recommended

Fire agencies commonly recommend keeping gutters free of leaves and installing metal gutter guards as part of broader property preparation.

A non-combustible gutter guard may help:

• Reduce larger leaf litter entering the gutter
• Reduce accumulation of twigs and bark
• Simplify surface-debris removal
• Reduce the amount of combustible material concealed in the gutter

It does not eliminate the need to inspect the roof and gutters before and during bushfire season.

Does Every BAL-FZ Gutter Guard Need 2mm Mesh?

No universal statement should be made that every gutter leaf guard at BAL-FZ must have a maximum 2mm aperture.

The maximum 2mm aperture is commonly required where mesh is being used as an ember guard or to protect a relevant opening.

Official guidance separately states that gutter and valley leaf guards, where installed, should be non-combustible. Treating these two provisions as identical can lead to inaccurate product claims.

When the 2mm Requirement Becomes Relevant

The mesh aperture is particularly relevant where the proposed system is intended to:

• Protect a ventilation opening
• Seal a gap beneath roofing
• Protect an eaves opening
• Screen a door or window
• Restrict embers entering another identified building opening

In those applications, the material requirement may also vary according to the BAL category and construction element.

Aperture Alone Is Not Enough

A 1.8mm mesh can still fail to provide the intended protection if:

• The wrong metal is used for the particular BAL-FZ application.
• There are unprotected gaps around the perimeter.
• The supporting components do not satisfy the project detail.
• The mesh is damaged or incorrectly fixed.
• The lid of an access panel creates an unapproved opening.
• Other gaps remain under roof ribs or corrugations.
• The product is used outside its tested or documented application.

The correct product must be combined with the correct installation detail.

Non-Combustible Material Requirements

Where a gutter or valley leaf guard is installed in the applicable bushfire construction context, it should be made from a non-combustible material.

Metal gutter guard products may include:

• Aluminium
• Corrosion-resistant steel
• Stainless steel
• Bronze in specialised screening applications

Plastic and Polymer Products

Plastic, foam and polymer gutter inserts should not be represented as equivalent to a non-combustible metal gutter guard.

Suitability depends on the applicable standard and project, but combustible products generally cannot satisfy a requirement expressly calling for a non-combustible gutter or valley leaf guard.

Avoid the broader claim that all plastic gutter products are universally unlawful on every bushfire-prone property. The correct statement is that they do not satisfy a construction requirement that specifically calls for a non-combustible leaf guard.

Non-Combustible Does Not Mean Flame-Zone Approved

A product being non-combustible does not automatically prove that it:

• Can be used for every BAL-FZ construction element
• Has passed any required BAL-FZ system test
• Can withstand direct flame exposure in the proposed application
• Meets the required fixing or framing provisions
• Will be accepted by the building certifier

Always distinguish the material property from approval of the complete system.

Can Aluminium Fine Mesh Be Used at BAL-FZ?

Aluminium mesh may be relevant as a non-combustible gutter or valley leaf guard on a BAL-FZ building, subject to the approved project documentation.

However, aluminium Fine Mesh should not be promoted as a universal BAL-FZ ember guard for every opening.

Why the Application Matters

At higher Bushfire Attack Levels, some ember-screening applications can have more restrictive material requirements than those applying at lower BAL categories.

Before using aluminium mesh as an ember guard at BAL-FZ, confirm:

• The exact opening or gap being protected
• The applicable AS 3959 provision
• The permitted mesh material
• The maximum aperture
• The required frame or support material
• The permitted perimeter gaps
• Any required system testing
• Acceptance by the project certifier

How Leaf Stopper Fine Mesh Should Be Described

Leaf Stopper Fine Mesh can accurately be described as:

• Non-combustible aluminium mesh
• 1.8mm × 1.8mm woven mesh
• Designed to help reduce pine needles, fine seeds and smaller debris
• The BAL-rated mesh option within the Leaf Stopper range
• Potentially suitable as an ember guard where aluminium is permitted by the applicable requirements

It should not be described as:

• Universally BAL-FZ compliant
• Suitable for every BAL-FZ opening
• A guaranteed method of passing inspection
• A complete Flame Zone construction solution
• Ember-proof or fireproof

Leaf Stopper Mesh Options

Leaf Stopper provides three aluminium Mesh Shield options.

Standard Mesh

• Aperture: 3.5mm × 3.5mm
• Aluminium thickness: 0.55mm
• Typical purpose: General leaves, twigs and larger debris
• Material: Non-combustible aluminium
• BAL status: Not the BAL-rated mesh option

Premium Mesh

• Aperture: 3.5mm × 3.5mm
• Aluminium thickness: 0.80mm
• Typical purpose: Applications where a thicker mesh is preferred
• Material: Non-combustible aluminium
• BAL status: Not the BAL-rated mesh option

Premium Mesh has the same aperture as Standard Mesh. Its primary distinction is the thicker aluminium.

Fine Mesh

• Aperture: 1.8mm × 1.8mm woven mesh
• Aluminium thickness: 0.40mm
• Typical purpose: Pine needles, fine seeds and smaller leaf matter
• Material: Non-combustible aluminium
• BAL status: The BAL-rated option within the Leaf Stopper range

Visit the Leaf Stopper Bushfire Protection page for the company’s current product information.

Which Mesh Should Be Used on a BAL-FZ Property?

Do not make the decision from the BAL category alone.

The selection should answer two separate questions:

1. Which non-combustible gutter leaf guard is permitted by the approved construction?
2. Is the same mesh also required or permitted to perform an ember-guard function?

The answer may be different for different parts of the same roof.

Choosing the Correct Roof System

Mesh selection is only one part of the installation. The roof-profile system must also be correct.

CORROGUARD®

CORROGUARD® is designed for traditional curved corrugated metal roofing.

• Uses corrugated saddles on the high points of the corrugations
• Uses Trimets at a compatible external gutter edge

TILEGUARD™

TILEGUARD™ is designed for concrete and terracotta tiled roofs.

• Mesh is positioned beneath the appropriate row of tiles.
• Trimets secure the Mesh Shield at the gutter edge.
• High-profile tiles may require carefully placed expansion cuts.

DEK-762™

DEK-762™ is designed for compatible DEK-762-style metal roof profiles.

• Uses DEKAFast saddles
• Does not use DEKGUARD™ Gripits
• Uses Trimets at a compatible external gutter edge

DEKGUARD™

DEKGUARD™ is designed for supported flat-based metal roof profiles.

• Uses Gripits secured to supported flat roof pans
• Uses Trimets at a compatible external gutter edge
• Requires confirmation of the roof manufacturer and exact profile

COMGUARD™

COMGUARD™ is designed for internal box gutters.

• Uses Clampers at a wall, parapet or vertical upstand
• Uses Gripits on the adjoining supported flat roof pan
• Does not use Trimets
• Is available in 250mm, 500mm, 750mm and 1000mm widths

Roof-Profile Fit Is Not Automatically Ember Sealing

A profile-specific gutter guard helps secure the Mesh Shield to the roof and gutter. It does not necessarily seal every opening into the roof cavity required by the BAL-FZ construction documents.

Separate protection may be required at:

• Roof and wall junctions
• Ridges and hips
• Valleys
• Roof vents
• Under corrugations or ribs
• Flashings
• Service penetrations
• Gables and eaves

Roof Gaps and Ember Entry

Ember protection depends on controlling openings throughout the roof and external building envelope.

A gutter guard attached near the roof edge does not automatically protect all gaps beneath the roof sheets.

Potential Ember-Entry Locations

Depending on the building, vulnerable locations can include:

• Open corrugations at the fascia
• Gaps beneath square roof ribs
• Unsealed roof and wall junctions
• Roof ventilators
• Damaged flashings
• Openings around pipes and conduits
• Gaps at ridge and hip cappings
• Unprotected eaves vents
• Missing or damaged sarking details

These may require separate non-combustible sealing or ember-guard construction as documented for the project.

Avoid “Gap-Free” Marketing Claims

A gutter guard may be fitted closely to the protected roof and gutter edge, but no manufacturer should claim that it makes the complete building gap-free.

Appropriate wording includes:

• Provides a supported fit along the protected gutter edge
• Helps reduce debris entering beneath the mesh
• Should be installed in accordance with the roof profile and project requirements
• Does not replace separate ember-sealing details elsewhere on the roof

Installation Requirements

BAL-FZ installation should follow the approved plans, product instructions and any directions from the bushfire consultant or certifier.

Before Installation

Confirm:

• The property’s BAL assessment
• The approved bushfire construction details
• Whether the proposed product is a gutter leaf guard, ember guard or both
• The permitted mesh material for the particular application
• The required aperture
• The exact roof profile
• The correct Leaf Stopper system
• Gutter, valley and box-gutter locations
• Roof openings requiring separate protection
• Access-panel requirements
• Installation and certification responsibilities

Inspect the Existing Roof and Gutters

Before covering the gutter, check for:

• Leaves and combustible debris
• Fine sediment
• Blocked downpipe entrances
• Corrosion
• Damaged roof sheets
• Failed gutter joints
• Loose flashings
• Inadequate gutter fall
• Obstructed overflows
• Known roof leaks

Gutter guard should not be installed over an unresolved roof or drainage defect.

Use the Correct Components

Do not mix:

• CORROGUARD® corrugated saddles
• DEKAFast saddles
• DEKGUARD™ Gripits
• COMGUARD™ Clampers
• Trimets intended for external gutter edges

Each component has a specific roof or gutter application.

DIY or Professional Installation?

BAL-FZ should not generally be treated as a simple DIY product-selection exercise.

Professional involvement is particularly important where:

• The construction requires certification.
• The mesh performs an ember-guard function.
• The roof has complex penetrations or junctions.
• The building is high or difficult to access.
• The project includes internal box gutters.
• The approved plans prescribe tested systems.
• The product differs from the original specification.

Use the Leaf Stopper installer directory to locate installation support, while confirming separately that the selected contractor can meet the project’s bushfire documentation and certification requirements.

Maintenance and Bushfire Readiness

No gutter guard is maintenance-free, and maintenance is particularly important on a bushfire-prone property.

Mesh can help reduce leaves and larger debris entering the gutter, but material may still collect:

• On top of the mesh
• At roof valleys
• Around branches
• At gutter corners
• Near downpipe outlets
• Inside the gutter as fine sediment

Prepare Before Bushfire Season

Property preparation should include:

• Removing leaves and twigs from roofs and gutters
• Clearing debris from the mesh surface
• Inspecting downpipe entrances
• Checking valleys and internal corners
• Checking that access lids remain correctly fitted
• Inspecting visible fixings and mesh damage
• Removing combustible material around the building
• Following the applicable property bushfire plan

NSW Rural Fire Service recommends cleaning leaves and twigs from gutters and installing metal gutter guards as part of broader property preparation.

Do Not Use a Universal Inspection Interval

There is no single inspection frequency suitable for every property.

The appropriate frequency depends on:

• Nearby vegetation
• Seasonal leaf and bark fall
• Wind exposure
• Recent storms
• Dust and pollen
• Roof design
• Accessibility
• The property’s bushfire-preparation plan

Inspect as conditions require and complete bushfire-season preparation before periods of elevated risk.

EasyAc® Maintenance Access

The EasyAc® range creates removable local access through gutter guard mesh.

Steel EasyAc®

• Original model introduced in 2010
• Manufactured from steel
• Uses a louvered lid
• The lid slides onto the base plate from one end

EasyAc20®

• Released in 2025
• Longer than the original model
• Manufactured from aluminium
• Available in a range of colours
• The lid is placed beside the slotted tabs and pushed sideways

Patented Screw-Free System

Both systems use patented internal tabs pushed underneath the mesh to hold the base plate in position.

The removable lid does not rely on screws, so a screwdriver is not required each time local access is needed.

Additional information is available at EasyAc Australia.

Using EasyAc® on a BAL-FZ Project

An access panel can support inspection and cleaning, but it also forms part of the installed surface.

Where the surrounding mesh is intended to perform an ember-guard function, confirm:

• Whether an access panel is permitted
• The required access-panel material
• The acceptable lid and base-plate construction
• The permitted perimeter gaps
• Whether the detail must be documented or certified

Do not assume that adding an access panel automatically preserves a project-specific BAL-FZ ember-guard detail.

EasyAc® Limitations

EasyAc® and EasyAc20®:

• Provide local inspection access.
• Do not make the gutter guard BAL-FZ compliant.
• Do not automatically clear a blockage.
• Cannot clear a restriction further down a downpipe.
• Cannot clear underground stormwater infrastructure.
• Do not replace the required roof or ember-protection construction.

BAL-FZ Gutter Guard Buying Checklist

Before ordering a gutter guard for a BAL-FZ property, confirm:

• The property has a valid BAL assessment.
• The approved plans and bushfire report have been reviewed.
• The role of the mesh has been defined as leaf guard, ember guard or both.
• The relevant AS 3959 construction element has been identified.
• The permitted mesh material has been confirmed.
• The required maximum aperture has been confirmed.
• The correct roof profile has been identified.
• The correct Leaf Stopper system has been selected.
• The proposed fixing components match the roof profile.
• Separate roof gaps and openings have been addressed.
• Valleys, box gutters and roof penetrations have been documented.
• Downpipe, sump and overflow access remains available.
• EasyAc® use has been approved where applicable.
• The gutter and roof have been cleaned and inspected.
• The installation responsibility has been assigned.
• Any required certification or completion evidence has been arranged.
• The ongoing inspection plan has been documented.

Understand the Complete BAL-FZ Requirement

The most important point is that BAL-FZ compliance cannot be reduced to a single statement such as “use aluminium mesh with holes below 2mm”.

For gutter and valley leaf guards, non-combustibility is the central general requirement. Where mesh performs an ember-guard function over a specified opening, aperture, material, framing, perimeter gaps and installation all need to satisfy the applicable project requirements.

Leaf Stopper Fine Mesh is a 1.8mm × 1.8mm non-combustible aluminium mesh and is the BAL-rated option in the Leaf Stopper range. It may be appropriate as a gutter leaf guard and in ember-guard applications where aluminium is permitted.

It should not be sold as a universal BAL-FZ ember guard or as a guarantee of building compliance.

Review the Leaf Stopper bushfire protection information, read the gutter guard guide for fire-prone areas and consult the project’s bushfire and building professionals before ordering.

Frequently Asked Questions

What does BAL-FZ mean?

BAL-FZ means Bushfire Attack Level — Flame Zone. It is the highest BAL category and involves an extreme risk of ember attack, radiant heat and direct exposure to potential flames.

Are gutter guards mandatory for BAL-FZ homes?

Not universally. Official guidance generally states that where gutter and valley leaf guards are installed, they should be non-combustible. The approved plans or bushfire report may nevertheless require a gutter guard for a particular project.

Must every BAL-FZ gutter guard have holes below 2mm?

Not necessarily. The maximum 2mm aperture commonly applies where mesh serves as an ember guard or protects a specified opening. A gutter leaf guard and an ember guard are not automatically the same construction element.

Can gutter guard also be used as an ember guard?

Potentially, but only where its aperture, material, supporting components and installation satisfy the requirements for the particular opening and BAL category.

Is aluminium allowed at BAL-FZ?

Aluminium may be relevant as a non-combustible gutter or valley leaf guard. Do not assume it is accepted for every BAL-FZ ember-screening application. Confirm the permitted material for the exact building element with the project certifier or bushfire consultant.

Is Leaf Stopper Fine Mesh BAL-FZ compliant?

It should not be described as universally BAL-FZ compliant. Fine Mesh is the BAL-rated option within the Leaf Stopper range and may be used as an ember guard where aluminium is permitted by the applicable Australian Standard and project documentation.

What is the aperture of Leaf Stopper Fine Mesh?

Fine Mesh has a 1.8mm × 1.8mm woven aperture.

Are Standard and Premium Mesh BAL-rated?

No. Standard and Premium Mesh are made from non-combustible aluminium but are not the BAL-rated options within the Leaf Stopper range.

Is Premium Mesh finer than Standard Mesh?

No. Both use a 3.5mm × 3.5mm aperture. Premium Mesh uses thicker 0.80mm aluminium.

Can plastic gutter guard be used at BAL-FZ?

A combustible plastic product does not satisfy a requirement calling for a non-combustible gutter or valley leaf guard. Confirm the exact construction requirements before selecting any product.

Does a fire-rated test make a gutter guard BAL-FZ compliant?

No. A fire or combustibility test may establish a particular material property, but BAL-FZ compliance depends on the complete system, application, installation and approved building documentation.

Will Fine Mesh stop all embers?

No product should be described as ember-proof. Fine Mesh is designed to help restrict ember entry in suitable applications, but performance also depends on materials, fixings, perimeter gaps, adjoining construction and maintenance.

Does gutter guard seal gaps beneath roof sheets?

Not necessarily. Separate construction may be needed beneath corrugations or ribs and around roof junctions, vents and penetrations.

Can I install a BAL-FZ gutter guard myself?

A simple product installation may be physically possible, but a BAL-FZ project commonly requires professional design, installation or certification. Do not alter approved construction details without appropriate confirmation.

Does gutter guard eliminate bushfire-season maintenance?

No. Leaves, bark and branches may remain on the mesh, while fine sediment may enter the gutter. Roof and gutter inspection remains an important part of bushfire preparation.

Can EasyAc® be used in BAL-FZ mesh?

Potentially, but its use should be confirmed for the specific project. Where the mesh performs an ember-guard function, the access-panel material, lid, perimeter and installation detail may require approval.

Who should confirm my BAL-FZ gutter guard selection?

Depending on the project, confirmation may be required from a bushfire consultant, architect or building designer, certifier or building surveyor, builder and relevant approval authority.