(02) 4577 4912
Unit 1, No.103 Railway Road (North) MULGRAVE NSW 2756
O'Mara Constructions has extensive experience designing & building new homes in high bushfire prone area's. Having lived in Hawkesbury all of our lives and with many of our sub-contractors we have experienced many bushfire's and seen the extent of fire on newly constructed homes & existing dwellings.
BAL RATINGS - WHAT DO THEY MEAN ?
As per AS3959 which is the Australian Standard for Construction of buildings in bushfire prone areas there are six categories of bushfire attack levels. They are;
BAL simply means "Bushfire attack level"
Flame zone is the highest level of attack and is usually when a site backs directly onto this bush, surrounded by bushland or at the top of a steep embankment. The BAL rating can be classified by self assessment or by a fire consultant but needs to be approved by council after consultation with the RFS (Rural Fire Service)
The categories of attack are determined by:
DESIGN CONSIDERATIONS FOR BUSHFIRE AFFECTED SITES
Homes that are designed in bushfire prone area's need special consideration in design of certain construction elements.
The main considerations are, but not limited to;
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EXTERNAL WALL CLADDING & STEEP SLOPING SITES
Many hopes built in bushfire affected area's are on sloping sites. This means standard slab on ground, brick veneer, tiled roof design, similar to many project homes simply don't work or any much too expensive and not practical.
There are numerous ways to design a home to suit the natural fall of the block in an economical way using specific materials that are lightweight but also bushfire proof.
There are numerous cladding products that are not suitable and need to be selected depending on the BAL rating. There are also numerous types of floor systems that can be used to reduce costs, take advantage of any possible views, make sub-floor storage possible and be fire safe.
We can also use a specialised block for high bushfire area's that will greatly assist in making the home safer. These are called "Timbercrete Blocks". They are available as bricks, blocks or panels in a wide variety of sizes, shapes, colours & textures. Timbercrete is a environmentally sensitive masonry block that is proudly Australian invented & owned.
Timbercrete is made from discarded timber (containing carbon) with other special additives moulded into blocks. They have great insulation when compared to normal brick veneer or clad homes. They are very easy to work with being lighter in weight than concrete blocks, look better and can be nailed and screwed just like timber. But there huge advantage is their improved fire rating when compared to other products. The standard 190mm block has a FRL240/240/240 which is excellent
It is a great product that we highly recommend and are happy to use on any of our projects. Please go to their website www.timbercrete.com.au for more information
We now also work alongside with "Wildfire Safety Bunkers" and can install a bunker with your new home or extension. These bunkers are constructed from a custom made concrete blend which is 100mm / 4" thick. This solidly reinforced concrete structure is not only incredibly strong at 65 mPa concrete strength - it is water and impact resistant. All components used on the door and its surrounds are made from high grade stainless steel. Every bunker door is fitted with an outside temperature gauge and the handle mechanism is designed in such a way that occupants inside the bunker can always release the door even if it has been padlocked from the outside.
All bunkers are fitted with a high temperature viewing port for outside observations. The bunkers are fitted with ventilation shafts that have shut off doors fitted inside the bunker. These doors are left open when not in use to stop the build-up of condensation and to allow fresh air in should someone find themselves unable to exit the bunker. All bunker locations and maintenance will be logged on Wildfires data base. The bunkers are easily installed (4 hrs in clean soil) and can be removed and relocated elsewhere at a later date if required.
Wildfire Safety Bunker Site Selection :
In the following criteria careful consideration must be given to the age of the occupants and or, any disabilities which could affect access and so impact on the site selection.
Setback from dwelling:
The Wildfire Safety Bunker access door is to be located a minimum of 10.0 metres and a maximum of 40.0 metres from the residential dwelling. Ten meters is considered a safe distance should the dwelling ignite following a bushfire event. Forty meters is considered a safe distance in terms of the time taken to get to the Wildfire Safety Bunker in an emergency situation. The access door must be oriented to face the dwelling. This orientation also protects the door from possible future development to neighbouring properties. Where possible the rear of the bunkers earth mound should be facing towards the at-risk fire direction. (i.e. - the door should be facing away from this fire direction).
Side and rear boundary setback:
The Wildfire Safety Bunker access door must be located a minimum of 6.0 metres from a side or rear boundary with the access door oriented towards the dwelling. This setback offers protection against the possible placement by neighbours of firewood and other fuel loads on the boundary line adjacent to an installed bunker and the doorway would be facing away from this potential threat.
Front and side street setback:
The Wildfire Safety Bunker access door must be located a minimum of 6.0 metres from the far boundary of a front street or 8m from the far boundary of a side street with the access door oriented toward the associated dwelling on the same allotment, or the front or side street.
Setback from outbuildings and other fuel loads:
The Wildfire Safety Bunker access door must be located a minimum of 10.0 metres from other outbuildings and fuel loads with the access door oriented towards the dwelling. (Example garden sheds, garages, wood piles, carports etc.). Radiant heat from these structures if ablaze could prolong the time spent in the bunker during a fire episode.
If this clearance is not achievable these hazards must be removed or relocated.
Select a site that is free from any objects (including non-combustible objects) that could possibly fall or be carried by high wind that may block or obstruct the access door to the bunker.
An access path must be established that provides a direct link from home to bunker. The path must be clear and level and have a tactile surface and must be maintained this way by the property owners as an ongoing maintenance item.
Ongoing Vegetation Management practices are to be implemented to maintain the BAL assessment that was undertaken for the purpose of obtaining the building permit issued for the construction of the Wildfire Safety Bunker.
For more information go to www.wildfiresafetybunkers.com.au or contact our office
"PASSIVE DESIGN" WAYS TO BUSHFIRE PROTECT YOUR HOME
There are numerous "passive" controls methods of protecting the home from bushfire.
Each project needs to be evaluated on a case by case basis but can include any or a combination of the following items to provide protection;
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PRACTICAL "ACTIVE" WAYS TO PROTECT YOUR HOME AGAINST BUSHFIRE
Other considerations need to be made for specific "active" control methods, such as;
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We also need to consider the materials used, the location of services, access to site, maintenance, just to name a few.We can design & construct a fire bunker. This is NOT design as a safe haven but more as a last option when escape is not possible
We can design & construct a fire sprinkler system with back-up hose reels supplied by a pool/tank/dam to protect the home to suit the site conditions and owner requirements More information can be found at the NSW rural fire service website;www.rfs.nsw.gov.au
We have current designs of homes that although can't guarantee complete bushfire protection they can at least be adapted to minimise all possible risks and increase the safety of the owner and their possessions to suit the conditions on site.
All our design will need to be viewed and approved by the RFS priory to any approval be ing granted by council or any work commencing on-site
FLAME ZONE (FZ) HIGH BUSHFIRE AREA'S
There are numerous special requirements for BAL bushfire rated homes whether being BAL 12.5/19/29/40
However FZ (Flame Zone) bushier rated homes have numerous very specific requirements that differ from other BAL ratings.
These can add a lot of cost to the construction of a home compared to other BAL ratings and can easily be an additional $100,000 to $200,000 or more, depending on the site conditions & RFS requirements
There are however ways to reduce these costs while maintaining the high bushfire protection required for FZ area's in a practical way.
Please contact our office for more information
FLAME ZONE (FZ) RATED WINDOW SHUTTERS
The rules for requirements for bushfire shutters in FZ areas have recently changed.
Where previously a standard type roller door could be used fire shutters now have to be FZ rated.
These shutters are much more detailed, more expensive and can be manually or electrically operated.
There are also rules on how they are to be operated to ensure safety of the home during a bushfire event.
Please contact our office for more information
A BUSHFIRE "PROOF" HOME
No one can (or at least should) guarantee that if you build a new home in a bushfire affected area that it will ever be "bushfire proof". Sometimes the fire is just too powerful & fast.
However there any many ways that you can increase your chances of protecting your home and make it alot safer. Some are expensive and are not negotiable by the RFS & council. There are however many small design changes & material specifications that can be made that don't cost a fortune and will increase the fire protection of your new home, extension or renovation.
Please contact our office for advice on how to improve the fire protection of your proposed new project.