22 April 2009 - A new national bushfire standard designed to improve the resistance of homes in bushfire-prone areas to better withstand bushfire attack, was finalised by Standards Australia on 5 March 2009. AS3959-09: Construction of Buildings in Bushfire Prone Areas has been accepted by the Australian Building Codes Board (ABCB) and will replace the 1999 standard currently referenced in the Building Code of Australia (BCA) when it is next updated in 2010.
While for most states and territories compliance with the standard won’t be mandatory until the BCA is updated next year, the Victorian and ACT Governments have chosen to implement the standard immediately as an amendment to their own building regulations. Therefore, residential buildings constructed from 11 March 2009 onwards in Victoria and the ACT must comply with the standard. The standard applies to new homes, as well as renovations and additions, and also to structures attached to or sharing a common roof space with the building classified as having to comply with the standard, such as garages, carports and verandas. The standard is based on a 1090K flame temperature, an increase from the 1000K benchmark used in the previous standard, meaning that it is likely more homes will be fall under the new standard.
The new standard uses a five step science-based method for assessing the likely threat to life and property of bushfire at building sites and to determine a site’s Bushfire Attack Level (BAL). The BAL system is based on the potential danger of the site and construction materials to heat flux exposure, expressed as kW/m2. In determining a site’s BAL, the Fire Danger Index (FDI), vegetation type, distance of the site from vegetation and the effective slope under the vegetation are taken into account. Based on an assessment of these variables, a site is assigned one of six Bushfire Attack Levels (BAL) ranging from low-risk BAL-LOW to very high-risk BAL-FZ (Flame Zone), where a site assessment of BAL-12.5 or higher mandates bushfire protection measures.
The six categories and their predicted risk levels are set out in the table below.
BAL–LOW - There is insufficient risk to warrant specific construction requirements.
BAL – 12.5 - Ember attack.
BAL–19 - Increasing levels of ember attack and burning debris ignited by windborne embers together with increasing heat flux between 12.5 and 19kW m2.
BAL-29 - Increasing levels of ember attack and burning debris ignited by windborne embers together with increasing heat flux between 19 and 29 kW m2.
BAL–40 - Increasing levels of ember attack and burning debris ignited by windborne embers together with increasing heat flux with the increased likelihood of exposure to flames.
BAL–FZ - Direct exposure to flames from fire front in addition to heat flux and ember attack.
GLAZING REQUIREMENTS UNDER AS 3959-09
Construction specifications for new buildings are required to reflect their location’s assessed level of bushfire exposure. AS3959-09 sets out construction requirements, including those for glazed elements, according to a site’s BAL. The requirements for windows and doors featuring glazing are summarised in the table below. The requirements are applicable to glazing that is less than 400mm from the ground or other similarly flat surfaces such as decks, carport roofs and awnings. Where double glazing is used, the below requirements apply only to the external face.
The screens referred to below must be mesh with apertures no larger than 2mm. For buildings with a risk level of BAL-12.5 to BAL-29, screens may be made of aluminium, steel or bronze. For home on a site designated BAL-40 or BAL-FZ, screens must be steel or bronze only.
If a wall is shielded by other parts of the building and not directly exposed to the source of the bushfire attack , it need not comply with the assigned BAL but rather the next lower category, but no lower than BAL-12.5, except where the exposed elevations have been determined as BAL-LOW.
Glazing Requirements for external windows, doors and roof penetrations (I.e. roof lights/skylights):
BAL–LOW - No specific requirements.
BAL – 12.5 - Windows: minimum 4mm Grade A safety glass or glass blocks with openable portion screened
Doors: side hung doors as for windows, sliding doors must comply with AS1288.
Roof penetrations: Grade A laminated safety glass OR polymer with a Grade A safety glass diffuser installed under the glazing. For IGUs, minimum 4mm Grade A safety glass must be used in the outer pane.
BAL–19 - Windows: minimum 5mm toughened glass with openable portions screened or glass blocks OR annealed glass completely screened
Doors: minimum 5mm toughened glass
Roof penetrations: as for BAL – 12.5.
BAL-29 - Windows: minimum 5mm toughened glass with openable portions and portions within 400mm of the ground or similar screened.
Doors: side hung doors to have minimum 5mm toughened glass with portions within 400mm of the ground or similar screened, sliding doors minimum 6mm toughened glass OR completely screened.
Roof penetrations: as for BAL – 12.5. Glazed roof penetrations in roofs with a pitch of less than 18 degrees to the horizontal must be protected by ember guards (mesh specifications as for windows).
BAL–40 - Windows: minimum 5mm toughened glass completely screened.
Doors: side hung doors must be minimum 6mm toughened glass with portions within 400mm of the ground or similar screened, sliding doors to have a fire resistance level (FRL, as defined in the BCA) of at least 30 minutes integrity only (-/30/-) OR completely screened.
Roof penetrations: Glazed assemblies for roof penetrations must have an FRL of (-/30/-). Glazed roof penetrations in roofs with a pitch of less than 18 degrees to the horizontal must be protected b ember guards (mesh specifications as for windows).
BAL–FZ - Windows: protected by a bushfire shutter OR openable portion screened and either: an FRL of at least 30 minutes integrity only (-/30/-) for the whole window system, or, tested to comply with AS 1530.8.2
Doors: as for windows.
Roof penetrations: must have an FRL of (30/30/30) or (-/30/30) when tested from the outside OR tested to comply with AS 1530.8.2
ALTERNATIVE OPTIONS: TESTING TO AS 1530
Any materials tested to and achieving the requirements of AS 1530 may be used in lieu of the applicable requirements of the relevant BAL. The main difference for the glazing resulting from the successful completion of this process is that screening for ember protection on the fixed windows need not be applied. However, screening on the openable parts of the windows and doors will still be required.
For materials proposed to be used in areas with a rating of BAL-12.5 to BAL-40, testing must be carried out in accordance with AS 1530.8.1: Tests on elements of construction for buildings exposed to simulated bushfire attack – Radiant heat and small flaming sources, to determine the glazing system’s BAL. BAL-FZ glazing must be tested to AS 1530.8.2: Tests on elements of construction for buildings exposed to simulated bushfire attack – Large flaming sources.
Note that the whole window system must be tested, not the glass alone. Both AS 1530.8.1 and AS 1530.8.2 illustrate two standard glazing system configurations, featuring a range of window styles. In order for a window system to be awarded general approval, both configurations must be tested.
Testing to AS 1530.8.1
AS 1530.8.1 outlines the methods for testing a glazing system to a particular BAL, up to a maximum of BAL-40. The external side of the system is exposed to radiant heat and cribs to simulate burning debris and the radiant heat flux recorded at regular intervals for a minimum of 60 minutes.
If a glazing system contains combustible elements that have the potential to compromise the performance of eaves or walls, the test must incorporate this detail. Any failure of either of these attributable to the glazing system will result in a failure of the glazing system.
If both configurations mentioned above are tested and approved, window systems can be used freely in the BAL threshold approved, up to a maximum height of 3000mm and an indefinite length, as long as individual panes are no longer than 2400mm. For a single configuration, the maximum size of the system intended for use can be tested up to 2400mm by 2400mm. Results of testing achieved at a particular peak heat flux level also apply to lower levels with the same or smaller sized cribs.
Glazed roof penetrations are to be evaluated separately for flat and pitched roofs. Flat roofs are those with a gradient of less than 15 degrees while assemblies intended for use in pitched roofs are tested in a representational roof with a gradient of 45 degrees. Once tested in a roof with a 45 degree gradient, the results will apply to roofs with gradients between 18 degrees and 75 degrees. The assembly must be tested at full size with a minimum test size is 2000mm by 1500mm.
Testing to AS 1530.8.2
Standard 1530.8.2 sets out methods for testing building materials exposed to direct flames. Testing of glazing systems is carried out in a fire resistant furnace, simulating exposure to direct flames. A 30 minute exposure period is followed by a 60 minute observation phase in which the performance of the system is monitored. The standard sets out seven key areas of performance and the results will indicate the period of exposure for which all criteria were satisfied.
The same differentiation between flat and pitched roof as discussed under AS 1530.8.1 applies to AS 1530.8.2 testing. The minimum test size for glazed roof penetrations is 1000mm by 1000mm.
Disclaimer: This information is presented as a means of providing an introduction to the glazing requirements of AS 3959-09: Construction of Buildings in Bushfire Prone Areas. It is not provided with the intention of giving a comprehensive understanding of all obligations in relation to glazing or any other construction process or material. Companies should make their own enquiries as to their obligations under the new standard.
25 Responses on New national bushfire building standard
It seems that the difficulty, at least for now, is finding products and materials that have actually been tested.
I have heard of a plaster that can withstand high temperatures…but someone should be making a list of materials as they are being made, and the costs of purchasing included.
good your work is good but some more detail send by your site ok sir
Sounds like these regulations have been made up by people who like ugly impractical and unaffordable housing and who hate trees.
some good ideas….however using a whole of house approch all i can see is big dollars to be able to build in high bal zones.
How about testing cost effective steel frame steel clad housing that can be 100% sealed against ember attack?
Why cant we use stainless steel thermos technology to build lightweight/strong/insulated shutters?
28 Sep 09 - From the editor.
Thanks, Michael, for your post — the balance between affordability and effectiveness was always going to be a fundamental sticking point, particularly with landowners wanting building regulation reforms ASAP. As soon as one building system or suite of materials is favoured, there is an inevitable outcry from providers of ‘better, cheaper alternatives’. The only solution, as I see it, is for regulations to stipulate performance standards — NOT specific systems or materials — which means owners are free to adopt any system they desire so long it complies with objective performance criteria.
I am slightly confused by the external windows for BAL29. Am I reading that I can use toughened glass 5mm double glazed and my openable portion screened with whatever? I am building a new house and I have 2 3m sliding doors that I will use 6mm toughened glass with hardwood timber…can I use any screening (retractable flyscreens) when I use those materials?
I recently wanted to extend my kitchen and found the front of the house where the kitchen is situated is rated BAL-FZ and the sides BAL 40. The plans have gone from an extension to almost a new house, and the restrictions are ridiculous. If there a fire I would never stay and protect my house after what I saw on TV last night. My existing house now requires the timber cladding to be replaced, the eaves around the house to be covered, all fly screens to be replaced etc etc. So the extension has doubled in price - I give up! After paying to have drawings done, I am now changing plans as it is far too costly and just plain crazy….especially as the rest of the house does not comply!
These new laws are ridiculous, the only windows I can get to put in my house I’m building are 13mm thick (to avoid shutters or steel mesh and meet the -/30/- rule), and they are unopenable. The cost is enormous! I’m better off building a bomb shelter.
We have built at house at Fletcher , we have been going round in circles for weeks regarding the window system complying with AS1530,8.2 and FRL-30-. Neither the council, independent certifiers or the builders understand it completely and all interpret the regulation differently, No window system available to that level was avilable when we built, certifiers wont pass the house, builders and council claim its not their problem. We now have a house that we legally cant move into and cant even sell, we will never get an occupation certificate!( unless we spend thousands per window to cover 3 sides of windows on a two story house with window shutters- UGLY- we have reached maximum borrowing capacity anyway). This is a joke and a nightmare, i thought regulations were to protect people not send them into finacial ruin!
We purchased a residential block about 4 years ago.
It is in Mt Helen Ballarat and Backs onto a larger block that is a bush block.
We finished designs and were about to get the enginerring done when we were advised by the CFA that we were in a High FZ area rating at a WMO 3 and if we were to build we would need to build a house that would bascially be fire proof.
We are at a lost,no one knows what to do. Unless you can spend big dollars we have purchased land that we cannot do anything with.
Dont despair. The glazing can be a prob but just check out certified upvc etc as alternatives as there performance is well documented in regards to the new laws. Im sure they arent the only solution. As well there are lots of excellent new products ie Timbercrete which is amazing ie 200mm block walls that are 240/240/240 and as green as and isnt any dearer…almost cheaper (aust invention/patent too!). All we need is some sort of attractive passive shutter system that can do light control so that its not a waste of money.
Im about to build in the blue mountains NSW and its made me rethink but I want to be in a building that I can comfortably shelter in and not ’sweat’ (sorry abut the pun) and watch the firestorm pass by.
I live in Seaford (a metropolitan suburb) opposite the beach and these codes also apply to us. It has increased building cost considerably, will impair views with hideous shutters and in the 15 years we have lived here there has not been one house that has burn’t down due to bushfires. Absolutely insane.
We are building in Brisbane which has not seen a bushfire in many many years - too humid! We were originally BAL-FZ due to one tree 6 metres from house and a gradient of more than 12 degrees. We managed to get it down to BAL-19 by getting rid of some trees - but we need to have mesh UGLY screens that stop breeze and view on 50 windows! I see a magazine ad for http://www.miglass.com.au that say they comply to BAL-40 with NO screens - I dont understand how this complies with the ridiculous standard but I will call them. This is the most ridiculous requirement I have ever seen - every house the has 1 tree within 100M will need crimsafe on every opening window - cost $$$$$$. Anybody know if they are thinking of reviewing this standard?
Our home backs onto Berowra Valley Regional Park in Berowra with a westerly aspect and very steep drop. We have planned a kitchen renovation and wanted to replace windows as part of the project. Hornsby council now tell us that we must comply with the BAL-FL requirements, even though we are replacing existing windows and not creating new ones. This means that we are required to go through the full DA process and install steel shutters which are ugly and cost $3700 for the small window and $6400 for the larger one. That’s on top of the $5500 quoted for the windows themselves. We can’t touch our treated pine deck which badly needs replacing without DA approval and we must use Steel and concrete. In 2002 when bush fires swept over and around our house the only damage was to our gardens. The house came out unscathed apart from a few scorches. These new regulations are going to make it virtually impossible for the average person to afford upgrades to any part of their home if in a Flame Zone. Our alternative is to leave our deck and unsafe plain glass windows as they are.
From the Editor John Power, 17 May 2010
Hi Karen,
Many thanks for your post — you raise many important issues about affordability; however, you have to ask yourself: When the flames are coming over the ridge and smoke is stinging you eyes, will you wish you had (a) the expensive window system that works, or (b) the affordable system that will not protect you? The reality is that the effective fireproofing of bush properties will cost more (usually 10-15 percent overall) than systems for a conventional inner-city home. You have to weigh up the risks and consider the worst-case scenario. My personal opinion is that opting for second-rate household fireproofing makes about as much sense as a skydiver opting for a parachute with holes in it!
By Steve
I am trying to build in Brisbane under BAL 40, where we dont have the same bush fire problems due to high humidity, These restrictions have been implemented in QLD with no consultation with industry as no body up here can offer solutions to the Windows and door problems. Unless you use shutters or install screens on the openable and fixed portion on your window. Surely this would lead to other problems such as fire started internally.As for the cost blowout it is ridculous, Certainly if fire is coming we will be leaving our home well before the fire gets close.
We have been on our acreage at Glenorie since 2004 and have been told that we are BAL-FZ. Unless we want to live in a concrete bunker where we can’t see the outdoors we moved here to be amongst, the cost of meeting these ridiculous requirements means we can’t build. We also could not sell the property if we tried. Right now we live in an old fibro shack on the property with broken windows covered by cardboard, holes through the walls you can pass a football through, lifting roof, large exposed spaces under the house etc. But the government would rather we lived in that with our 18 month old than something infinitely better but still realistic. (Right now I am thinking of an elaborate set up of lovely safari tents for my new house, as this movable accomodation would be quite legal!)
This is all politics and nanny state gone mad. People should have the right to choose to be responsible for themselves. Tell the fire fighters not to risk their lives to save houses that can always be re-built, and get out early if you choose the ‘risk’ of living in the bush.
I am inclined to the belief that such regulations should be recommendations only. Then, when building, one could decide; or, if purchasing a house, one could enquire as to its rating. Of course, many politicians feel they have kudos to gain by pushing such legislation and, whilst happy to dwell on the benefits, are unwilling to acknowledge the negative aspects (see previous posting).
Another interesting point, as I see it, is that this is a “taking” of “property” in the constitutional sense, i.e. a limitation of one’s enjoyment of one’s property, and thus is compensable. If the legislation makes no mention of compensation for this “taking”, then it cannot comply with the national Constitution, and all legislation, State and Federal, must comply in order to be legal. This point, it seems to me, also applies to almost all planning and building legislation passed since Federation.
The window requirements for BAL–FZ above include “protected by a bushfire shutter”. Does AS3959 (or some other standard) define what is meant by “bushfire shutter”?
For example, as an alternative to standard roller shutters can I have metal screens that I manually fix to the windows when a fire threatens? Would these screens need to be certified in some way? I recognise that the more manual a system is the more likely it won’t get used but will it meet the Building Code requirements?
Thanks
we are building a house in Mt Victoria in the blue Mts on a steep block which faces north-east. Fires have never come from this direction up the ridge; the local fire chief confirms this! Yet we are required to put firescreens on ALL windows and doors (of which there are lots to capture the winter sun)facing this direction. I agree with oter comments about councils being implicit in the financial ruin of those seeking to build!
We have fire-proof materials everywhere in the house + have supplied (as required) a 10000L tank for use for fire services, not ourselves. After this, it should be just our insurance policy and common sense which takes over. This it fear of litagation gone mad!
We are building in Pacific Pines and of course were not advised by the developer that the block requires a bushfire management plan. Anyhow from what I am reading above it appears windows, doors and screens apply. We are being asked by the builder to use hardwood timber frames, metal vent pipes, ember guards, kwila timber posts, nylon weather seal to bottom of sectional overhead garage doors which is more than 16 metres away from the trees etc etc etc. Is this correct or do we only need the windows & screens covered? This adds $27600 onto the price of our home.
we have battled away to save enough to buy our block and now we need more money to satisfy a knee jerk reaction from our people in leadership. These leaders need to understand that this ridiculous leglislation will attract a groundswell of negative opinions in its pathetic attempt to control the people. This is ment to be a free country ! from where i’m sitting its a battle to save enough, a battle to satisfy desk sitters, a battle for ordinary people to build our own home. We are not young and free - we are older,and in debt, and no home ! are you there julia?
All for bush fire protection for houses, but to have an urban house in a subdivision that has forest vegetation on one side with only 2 trees within 25m having to be built to the same level of protection as a house surrounded by walls of trees 20m from the house is just ridiculous.
“When the flames are coming over the ridge and smoke is stinging you eyes”…We will jump in our car, drive the 1500m to the lake and sit on the wharf. If the fire burns through the 1500m or so of urban subdivision, we’ll just have to swim for it.
As for jumping out of a plane with a holey parachute, it’s a bit hard to jump in the car after you get in the plane….and if you live in a area surround by bush and all evacuation roads are likely to be fire effected….you should have a fire bunker, preferably without holes!
We have finnaly got town planning approval after over 6 months of dealing CFA & council. The BAL rating by a so called expert told us BAL 19 the CFA say FZ. So we now have to try and build to FZ. WE have had to move the home 30m from our boundry away from the state forest 70m away. Then a condition on our town planing is that we plant 20 more trees on our land? The FZ windows are nearly imposible.I dont know how the CFA became the building experts over night? An why bother with a BAL system if the CFA dont use the same system. Has anyone tried VCAT to try and lower a BAL assesment?
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