as3959 marysville pto

8/6/2019 AS3959 Marysville PTO

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New Bushfire Construction Regulations

David Kearsley

Senior Technical Advisor, Technical and Research Services

February 2009

Overview

Regulatory Framework

Introduction of AS 3959 - 2009

Construction Requirements

BAL Assessments

Worked Example - BAL Assessment

Attached Structure and Shielding

AS 1530.8 Testing Private Bushfire Shelters

Guidance Information

Regulatory Framework and Background


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Building Legislation Hierarchy

STATE & TERRITORY BUILDINGACTS

STATE & TERRITORY BUILDINGREGULATIONS

TECHNICALSTANDARDS

ADMINISTRATIVE MATTERS

AdministrationAppealsRegistrationsRefurbishmentsBuilding standard

Building Code of Australia

Takes effect 1 May each year

BCA is the communitys minimum standard for new buildingwork

Referenced in State & Territory building law

Developed by Australian Building Codes Board (ABCB)

Amended annually

Not best practice

To overcome market failure

Solutions must be cost effective

Building Code of Australia (BCA)

Building Solutions

Performance Requirement

Functional Statement

Objective

Alternative SolutionDTS Provisions

Guidance

Mandatory

Methods ofachievingcompliance

Documentary Evidence

Verification Method

Expert Judgement

Comparative Analysis

Prescriptivemeasures

Assessmentmethods


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AS 3959 2009 Construction in BushfireProne Areas

History of AS3959

Ash Wednesday 1983

First Edition 1991

Second Edition 1999 (current in BCA) - 2 levels of construction

Amendment No. 1 2000 (Level 3 construction)

Amendment No. 22001 (Fire retarded-treated timber)

Third Edition (2009) under revision

Interim Standard for Victoria February 2009

Fast track publication 11 March 2009


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Enacted in Victorian buildinglegislation 11 March 2009

Applies to all new residentialbuildings and includes a newsystem of Bushfire AttackLevels, from BAL-Low to BAL-FZ

Does not apply to existinghomes or private bushfireshelters (bunkers)

Will apply throughout Australiafrom May 2010

Australian Standard AS3959-2009

AS 3959 2009 Design Objectives

A structure should be able to withstand ember attack prior tothe arrival of the fire front with minor levels of assistance fromoccupants

The structure should be able to provide a safe refuge whilstthe fire front passes

Provide the building with a level of protection while the frontpasses

Any residual burning of elements of construction after the front

has passed should be capable of being extinguished easily byresidents once external conditions are tenable

These Measures cannot guarantee building survival due to theunpredictable nature of fire, and difficulties associated withextreme weather conditions and protecting a typical house (forexample, window breakage, falling trees, impact of debris)

Structure of AS3959-2009

Preface

Foreword

Scope

Objectives

Disclaimer

Assessment (Section 2)

Construction (Sections 3 to 9)

Appendices Worked example, Assessment Method 2 etc


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Structure of AS3959-2009

General (Section 3)

Low (Section 4) no requirements

BAL 12.5 (Section 5)

BAL 19 (Section 6)

BAL 29 (Section 7)

BAL 40 (Section 8) BAL FZ (Section 9)

Comparison of Structure of AS3959-2009

Bushfire Attack

Level

Radiant heat Exposure

AS 3959- 2009AS 3959-1999

Low Insignificant Insignificant

12.5 0 to 12.5kW/m2 Level 1

19 12.5 to 19 kW/m2

29 19 to 29 kW/m2

40 29 to 40 kW/m2 Level 3

FZ40 kW/m2 plus

(flame contact)Silent

Improvements to AS3959-2009

1. Increased number of construction levels (6) based on heat fluxexposure thresholds defined as Bushfire Attack Levels (BAL)

2. Two options for determining BAL

1. Simple step by step approach with tables or

2. Detailed calculation procedure (compatible with fire safetyengineering approaches)

3. Both methods account for climate, slope of ground andvegetation variations in States and Territories

3. The slope of ground definition has been clearly specified

4. Improved formatting / clarity5. Construction sections have been reorganised to group specific

construction requirements by Bushfire Attack Levels


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Improvements to AS3959-2009 (Cont)

6. Construction requirements revised based on defined exposurelevels (BALs) - measurable - allowing prescribed solutions tohave consistent performance

7. Nomination of test methods AS 1530.8

1. Allows innovative and proprietary products to be evaluatedagainst test methods AS 1530.8 removing major barrier toinnovation

8. Operational specification for shutters

9. Concessions for non-exposed facades are included.

10.Attached structures, such as garages, have been included.

AS 3959 - 2009 BAL Assessment

Flow Chart provided in Handouts

Identifies the BAL level andassociated construction sections


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BAL Assessment Simplified Method

Step Clause Procedure

Step 1 2.3Determine the relevant Fire Danger Index (FDI) Table2.1

Step 2 2.4Determine the vegetation classification type(s) - Table 2.3and Figure 2.3

Step 3 2.5Determine the distance of the site from the classifiedvegetation site(s) Figure 2.1

Step 4 2.6Determine the effective slope(s) under the classifiedvegetation types(s) Figure 2.2

Step 5 2.7Determine the Bushfire Attack Level (BAL) from theappropriate table Tables 2.4.1 to 2.4.4 & Table 2.5

Excluded Vegetation

Vegetation of any type which is more than 100 m from the site.

Single areas of vegetation less than 1 ha in area, not within 100 m ofother areas of vegetation being classified.

Multiple areas of vegetation less than 0.25 ha in area and not within20 m of the site, or each other.

Strips of vegetation less than 20 m in width regardless of length andnot within 20 m of the site or each other, or other areas of vegetationbeing classified.

Non-vegetated areas including waterways, roads, footpaths, buildingsand rocky outcrops.

Low threat vegetation including managed grassland, maintainedlawns, golf courses, maintained public reserves and parklands,botanical gardens, vineyards, orchards, cultivated ornamentalgardens, commercial nurseries, nature strips and wind breaks.

BAL Assessment Worked Example


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Determine the distance to the classified vegetation

Determine the slope under the classified vegetation

Slope - refers to the slope under the classified vegetation in relation tothe building not the slope between the vegetation and the building

Determine the classified vegetation


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1. Relevant FDI..802. Slope >0 to 53. Vegetation Class .Forrest4. Building Location ..30m

BAL Assessment - Detailed Method

Determine the relevant FDI in accordance with Clause B2.

Determine the predominant vegetation classification, fuel loads andvegetation height in accordance with Clause B3.

Determine the effective slope of the predominant vegetation classification inaccordance with Clause B4.

Determine the site slope of the building site in accordance with Clause B5.

Determine the distance of the site from classified vegetation in accordancewith Clause B6.

Determine the elevation of receiverin accordance with Clause B7.

Determine flame width in accordance with Clause B8.

Calculate the flame length in accordance with Clause B9.

Calculate the radiant heat flux in accordance with Clause B10.

Determine the Category of Bushfire Attack (BAL) in accordance ClauseB11.

ANY QUESTIONS


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AS 3959 Construction

BAL and Corresponding Construction Sections

BushfireAttack Level (BAL)

Classified Vegetationwithin 100m of the site &

Heat flux exposurethresholds

Description of predicted bushfire attackand levels of exposure

ConstructionSection

BALLOW See Clause 2.4.2There is insufficient risk to warrant specificconstruction requirements.

4

BAL 12.5 12.5 kW/m2 Ember attack 3 and 5

BAL19 >12.5 kW/m219 kW/m2Increasing levels of ember attack andburning debris ignited by windborneembers together with increasing heat flux.

3 and 6

BAL29 >19 kW/m229 kW/m2Increasing levels of ember attack andburning debris ignited by windborneembers together with increasing heat flux.

3 and 7

BAL40 >29 kW/m240 kW/m2

Increasing levels of ember attack andburning debris ignited by windborneembers together with increasing heat fluxwith the increased likelihood of exposure toflames.

3 and 8

BALFZ > 40 kW/m2Direct exposure to flames from fire front inaddition to heat flux and ember attack.

3 and 9

1. Sub-floor supports

2. Floors

3. External walls

4. Glazing & doors

6. Verandas,decks, steps,ramps & landings

7. Water & gas pipes

5. Roofs

Roofs includeveranda and attachedcarport roofs,penetrations, eaves,fascias & gables; andgutters & downpipes


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Attached Structures

Where any part of a garage, carport, veranda or similar roofedstructure is attached to, or shares a common roof space with abuilding required to comply with this Standard, the entiregarage, carport, veranda or similar roofed structure shall

comply with the construction requirements of this Standard, as

applicable to the subject building, or

Attached Structures

Be separated a wall that extends to the underside of a non-combustible roof covering; and

Has an FRL of not less than 60/60/60 for load bearing walls and -/60/60 for non-load bearing walls when tested from the attachedstructure side; or

Is of masonry, earth wall or masonry-veneer construction with themasonry leaf being not less than 90 mm in thickness; and

Has openings protected as follows

Doorways by /60/30 self closing fire doors. Windows by /60/ fire windows permanently fixed in the closed

position.

Other openings by construction with an FRL not less than /60/.

Control and construction joints, sub-floor vents, weepholes andpenetrations for pipes and conduits need not comply with the above.

Shielding

The construction requirements for the next lower Bushfire Attack

Level (BAL) than determined for the site may be applied to an

elevation of the building where the elevation is not exposed to the

source of bushfire attack.

An elevation is deemed not to be exposed to the source of bushfire

attack if all of the straight lines between that elevation and the source

of bushfire attack are obstructed by another part of the building. This

is shown in Figure 3.1.

The construction requirements for a shielded elevation must not be

less than that required for BAL12.5, except where the exposedelevations have been determined as BALLOW.


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Testing to AS1530.8

AS1530.8 Testing

AS 1530.8.1 & 2 - Methods for full scale fire tests on building

materials, components and structures

Tests on elements of construction for buildings exposed to

radiant heat and small flaming

Test elements such as

Windows, Doors, Service Penetrations, Eaves/Gutter Details,Roofs, Verandas and Decks, Exposed Structural Elements (eg

Posts/Columns), Sub Floor Spaces, and Roof lights

AS1530.8 Testing

The outcome of the testing will be a rating similar to:

AS 1530.8.1 - BAL 12, BAL 19, BAL 29, BAL 40

AS 1530.8.2 - BAL FZ

Where the number refers to the peak radiant heat flux appliedduring a test and FZ refers to a specimen exposed to thestandard heating regime of AS 1530.4

A BAL19 system would have satisfied the performance criteriawhen subjected to an AS 1530.8.1 test at a peak heat flux of19kW/m2

A BAL FZ system would have satisfied the performance criteriawhen subjected to a test in accordance with AS 1530.8.2.


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AS1530.8 Testing

0

10

20

30

40

0 2.5000 5.0000 7.5000 10.0000

Draft AS 1530.8.1 Idealised Exposure Conditions

Rad

iantHeat-kW/m2

Time - s

BAL 40BAL 29BAL 19BAL 12

AS1530.8 Testing


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ANY QUESTIONS


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Private Bushfire Shelters

Government monitoring activity in new market

Dubious products on market

Sales increase dramatically after acknowledgment ofpotential danger of upcoming fire season

ACCC takes action against some manufacturers foradvertising that products are Standards compliant

Royal Commission urged action Building Amendment (Private Bushfire Shelter

Construction) Further Interim Regulations 2009introduced November 11th 2009

Building Amendment (Private Bushfire SheltersConstruction) Interim Regulations 2009

%of

buildingssurviving

Bushfire Severity

AS 3959-2009Private Bushfire Shelter

BAL 40 & FZ& Beyond ?

BAL-Low-19? BAL-29?

What Are the regulations trying to achieve?


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What should the design of a Private Bushfire Shelter achieve ?

Protection from fireSafe access and

egress

Space forall essential

items

A senseof safetyand well-

being

Adequateair supply

Adequatefacilities

A way of knowingwhats going on

outside

A means ofidentification

Amends both the Regulations and the BCA

A new BCA classification (Class 10c)

New Performance Requirement P2.3.4A

NO Deemed-to-Satisfy provision (or Australian Standard)


New definit ion

Private bushfire shelter means a building or part of a building that

may, as a last resort, provide shelter for people from the immediate

life threatening effects of a bushfire,

New classification

Class 10c a building being a private bushfire shelter.

The period of the bushfire event is the reasonably estimated period of

time beginning from entry into the building by occupants prior to the

fire front arriving and concluding when the fire front has passed and

the external environmental conditions are no longer untenable.



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New Performance Requirement P2.3.4A Private bushfire shelter

The design and construction of a Class 10c building associatedwith a Class 1 building provided for use during the event of abushfire must take into account the requirements necessary tomake reasonable provision for the amenity of the Class 10cbuilding and the safety and health of people using that building

during the period of a bushfire event.


The design and construction of a Private Bushfire Shelter(Class 10c) must provide for

1. safe access to the building; and

2. appropriate sanitary and other facilities; and

3. a means of determining the external environmentalconditions; and

4. safe egress from the building; and

5. a means of identification of the location of the building for thepurpose of rescue.


The design and construction must have regard to

1. the number of occupants likely to use the building; and

2. actions to which the building may be subjected; and

3. the effects of nearby permanent features such as topography,vegetation and other buildings; and

4. the potential external fire intensity; and

5. the prevention of conditions within the building that areuntenable.



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Regulation limits the circumstances in which a buildingsurveyor can issue a permit to that which relies on:

A Building Regulatory Advisory Committee (BRAC) accreditedproduct, or

A Building Appeals Board (BAB) determination under s160A ofthe Act, or

A Certificate of Compliance from fire safety engineer who didnot do the design


Guidance Information

Owner-builder

Certificate of Consent (from BPB)

Insurance (for works > $12k onsale)

Registration required forsub-contracted works > $5k

Training courses available

Need time, expertise &experience!


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Registered Builder

Registration number (DB-)

Insurance (on work > $12k)

Contract (on work > $5k)

Continuing education (CPD)

Dispute resolution (BACV)

Memberships (HIA, MBA)

get 3 quotes & referee details.

For more information:

www.buildingcommission.com.au /publications

Available from SAI Global

http://infostore.saiglobal.com/store/default.aspx

Currently $97.30

HB 330 - Living in BushfireProne Area also available

T | 131 242 F | 1300 65 49 49

Unit 3 18 Salmon Street

Port Melbourne

Australian Standard AS3959-2009


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Contact Us

Building CommissionGoods Shed North733 Bourke StDocklands VIC 3008

P.O Box 536Melbourne VIC 3001

T | 1300 815 127

E | [email protected]

ANY QUESTIONS

as3959 marysville pto

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