How To Defend Your House From A Bushfire

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1 Establishing and Maintaining a Building Protection Zone If you live within a bushfire prone area there will always be a risk that you may be injured or killed during a bushfire and/or your property destroyed. WHAT IS A BUSHFIRE PRONE AREA? You are considered to live in a bushfire prone area if your house is either within, or within 100 metres of; unmanaged bushland, grassland or plantations, which cover more than one hectare in area. The only vegetation not considered bushfire prone is vegetation managed in a minimal fuel condition such as: maintained lawns, golf courses, maintained public reserves and parklands, botanical gardens, vineyards, orchards, cultivated gardens, commercial nurseries, nature strips and windbreaks. When a bushfire threatens your safest option is to leave early. However to reduce the risk of your home being damaged or destroyed in a bushfire you need to maintain a Defendable Space between your home and any nearby unmanaged vegetation. The main component of this will be a Building Protection Zone. On a larger lot you should also have a Fuel Modified Buffer Zone to complement your Building Protection Zone. If you choose to stay and defend your home during a bushfire a Defendable Space is essential, A Building Protection Zone will help reduce the risk of your home being damaged or ignited by direct flame contact or the intense heat radiated from the fire front. It will also reduce the risk from wind-blown burning embers that are generated by bushfires. The term bushfire protection is commonly used but is a bit misleading because it is not possible to ensure that a house in a bushfire prone area will not be damaged in a bushfire, particularly on days with severe fire 1

2 weather. Bushfire protection really means reducing the risk to your house to a level where it has a reasonable chance of surviving most bushfires. How big should my Building Protection Zone be? The Building Protection Zone provides a space around buildings with minimum fine fuel that allows them to be defended from bushfires. It also reduces the risk of wind-blown burning embers from bushfires starting spot fires close to buildings. The Building Protection Zone extends outwards from the walls of the building being protected. Bushfires move faster and burn with higher intensity when moving up a slope. Therefore your Building Protection Zone needs to be wider where the bushfire threat is downslope of your house. The Tasmania Fire Service recommends the following minimum widths for your Building Protection Zone. Slope 1 (degrees) Building Protection Zone Width m 5 20 m m m m 1 For downslope, and across slope, fire approaches use the widths for 0 degrees. 2 - Distances are measured outwards from the wall of the building towards the fire hazard. Roads and other cleared areas on adjoining properties can form part of your Building Protection Zone, but do not clear vegetation on adjoining properties without the landowner s permission. If you cannot fit your Building Protection Zone within your property, talk to your neighbours about managing the bushfire hazard on their property. Council may also be able to help you through issuing a hazard abatement notice which requires landowners to manage the vegetation on their properties where it is a threat to nearby houses and other assets. Within the Building Protection Zone there should not be enough fuel on the ground to carry a fire from surrounding bushland to the wall of your house, or for wind-blown embers to start small fires. To establish your Building Protection Zone it is most important to remove fine fuel that is on the ground and thin out the shrub layer. Tree removal is not so important, however you should remove or prune trees that touch or overhang your house, and, if necessary, thin out or prune the trees in your Building Protection Zone to ensure the canopies don t touch. 2

3 General landscaping guidelines for a Building Protection Zone are as follows: use only mown lawn, bare ground (driveways, paths etc) or non-flammable native succulent ground cover plants immediately adjacent to buildings (within 2 metres) total shrub cover should be less than 20% shrubs should be isolated or in small clumps; avoid continuous canopies new trees should not be planted closer to buildings than their expected full height avoid planting or retaining trees and shrubs with rough fibrous bark, or which retain shed bark in long strips (ribbon bark) (e.g. any of the stringybark group of eucalypts) avoid planting or retaining trees and shrubs that retain dead material in their canopies (e.g. most conifers, and most Melaleuca and Leptospermum species) trees and large shrubs should be pruned to remove branches within 2 m of the ground avoid planting or retaining shrubs under trees canopies of trees and shrubs should not touch walls or overhang your house 3

4 avoid vines on walls and pergolas avoid brush fencing avoid planting or retaining trees and shrubs that deposit large quantities of litter in a short period, particularly in spring and summer combustible mulches should not be used, except in very limited quantities around the base of shrubs; use non combustible mulches, such as pebble or gravel shrubs should not be allowed to grow to within 2 m of windows with annealed (standard) glass, or within 1 m of windows with heat toughened glass or walls with timber cladding buildings with combustible cladding down to ground level should have a minimum 400 mm wide strip of bare earth, gravel, pavers, etc. around their base or non combustible material for the first 400 mm above ground level. locate any combustible materials, such as woodpiles, flammable fuel stores etc., outside the Building Protection Zone, and preferably on the eastern side of your house. Landscaping the Building Protection Zone with indigenous species of relatively low flammability would be ideal. This will ensure that the vegetation itself is of relatively low flammability, and reduce the amount of maintenance required to maintain fuel minimal fuel conditions. Plants with relatively low flammability are those with soft fleshy leaves and stems which have a high water content. Plants with a relatively high flammability are those with hard, dry leaves, particularly those with dense masses of small leaves and those that contain oil glands in the leaves. The Country fire Authority of Victoria has produced a useful online key for selecting low flammability plants for your garden (see You can also use it to assess the flammability of the plants you have. From this high fuel load Do I also need a Fuel Modified Buffer Zone? To this low fuel load If you live on a larger property near a lot of bushland you should also maintain a Fuel Modified Buffer Zone around your Building Protection Zone. The Fuel Modified Buffer Zone forms a concentric ring around the 4

5 Building Protection Zone and has fine fuel loads reduced sufficiently to ensure that a high intensity bushfire will not reach the Building Protection Zone. It also helps protect your home from radiant heat. The width of the Fuel Modified Buffer Zone varies with slope of the land over which a bushfire can approcah and the type of vegetation. The Tasmania Fire Service recommends the following minimum widths for your Building Protection Zone. Slope 1 Fuel Modified Buffer Zone Width 2 (degrees) Grassland Forest, woodland, scrub & heath 0 10 m 15 m 5 15 m 25 m m 30 m m 45 m m 50 m 1 For downslope, and across slope, fire approaches use the widths for 0 degrees. 2 - Distances are measured outwards from the edge of the Building Protection Zone towards the fire hazard. General recommendations for landscaping and maintaining the FMBZ include: understorey shrub cover should not be more than 30% total cover, and the cover should be discontinuous trees and large shrubs should be pruned to remove branches within 2 m of the ground fine fuels at ground level must be maintained at less than 5 tonnes per hectare (a covering of leaf litter 2 cm thick over approximately 50% of the ground surface gives a fuel load of 5 tonnes per hectare). 5

6 Tasmania Fire Service (2005) Guidelines for Development in Bushfire Prone Areas of Tasmania Removing Vegetation Removing trees and some types of vegetation, particularly threatened plant species and plant communities,may require various approvals and permits. Please contact Council s Fire Officer on before clearing. When removing vegetation to create a Defendable Space the order of preference for vegetation removal should be: 1. weeds 2. other introduced species (except ornamental plantings you want to keep) 3. native trees and shrubs with rough fibrous bark 4. indigenous trees and shrubs that hold dead leaves and twigs in their canopy 5. relatively flammable sclerophyllous species (those with stiff, hard leaves). When removing native trees, take out any with rough, fibrous bark first. 6

7 How to Dispose of Cleared Vegetation The vegetation you remove to create your Defendable Space should be disposed of so that it will not continue to be a fire hazard, and, if it includes weeds, will not spread them. Vegetation disposal options include: Council s free Domestic Kerbside Green Organics Collection service by calling burning in piles or an incinerator if you are on a lot larger than 2000 square metres. composting; best for light prunings, grass clippings and leaves. mulching; best for small branches, dry twigs etc. that are hard to compost. Large tree trunks can be cut up for firewood, or left as a feature in your garden as long as they are not close to your house or other buildings. Stump grinders can efficiently remove tree stumps. Look in the yellow pages for stump grinding contractors in your area. Burning in Piles or in an Incinerator Burning cleared vegetation in a number of small piles (less than 2 m diameter) is generally easier than trying to burn a large pile. Ensure that the ground around your burn is completely clear of any combustible material for at least 2 m for a small pile, and at least 5 m for a large pile. The heat from your burn can scorch nearby shrubs and trees so place your piles in an open area with no overhanging tree branches or shrubs within 5 m. Burn your piles or incinerator when the weather is calm and cool, and there is no forecast of strong winds for at least 24 hours (small pile), or 3 days for large piles and windrows, particularly if they contain large logs or stumps. Please note that your burn should not create a nuisance. Inform your neighbours before you burn and make sure the material you are burning is dry so as to minimise smoke. You will need a permit for your burn during a fire permit period, please contact the Tasmania Fire Service (TFS) on Also, before you light a fire (even if you have a permit) contact the TFS on to let them know. Otherwise your local brigade may be called out to your fire, and they will not be very happy. On the other hand, if you feel that your fire is getting out of control call the TFS on 000 immediately. 7

8 Checklist for Pile Burns 1. You are not permitted to burn in the open on lots less than 2000 square metres use other methods to dispose of cleared vegetation. 2. Pile material to be burnt in a clear, open area; keep piles small. 3. Clear all fuel for at least 2 m around your pile. 4. Obtain a permit from the Tasmania Fire Service if you are burning during the fire permit period. 5. On the day of your burn check the weather conditions for the next 24 hours; postpone your burn if windy conditions are forecast. 6. Inform your neighbours of your burn. 7. Just before you light your pile call the TFS on and register your burn. 8. Do not leave your burn unattended. Keep a charged hose, or other means to control your burn, close at hand. Please do not dispose of cleared vegetation in nearby bushland, even if it is on your property. This just increases the bushfire hazard and can help spread weeds. Need Help For further information and advice please call Limitation These guidelines are designed to assist landowners manage the bushfire risk on their property. Implementation of these guidelines can reduce the risk from bushfire but will not ensure safety of life and property in bushfire prone areas under all conditions and circumstances. Some Common Bushfire Terms Backburning A fire started intentionally along the inner edge of a fireline during indirect attack operations to consume the fuel in the path of a bushfire. This is usually the only method for controlling large wildfires. Building Protection Zone An area between buildings and the fuel modified buffer zone, where fine fuels are maintained in a minimum fuel condition to ensure that the zone acts as a barrier between the building and a bushfire. 8

9 Bushfire A general term used to describe a fire in vegetation. Includes wildfires and fires lit for various management purposes (planned fires). Bushfire Hazard The potenial severity of a bushfire. The simplest classifications of bushfire hazard use a combination of slope and vegetation type (eg rainforest, wet forest, dry forest, shrubland, grassland). Bushfire Risk In general, bushfire risk is the probability of a wildfire starting and spreading, but it can also be used to describe the likelihood of an asset, such as a building, being damaged or destroyed in a bushfire. Fine Fuel Dead plant matter less than 6 mm in diameter and live plant matter less than 2 mm in diameter (including grasses, bracken, leaves, bark, and twigs and branches) that ignites readily and burns rapidly when dry. Fine fuel is what burns at the fire front and contributes directly to fire behaviour. Increasing fine fuel loads increases the rate of spread and intensity of fire fronts. Fire Danger Index (FDI) A relative number denoting an evaluation of rate of spread, or suppression difficulty for specific combinations of temperature, relative humidity, drought effects and wind speed. Fire Danger Rating (FDR) A relative evaluation of fire danger derived from the Fire Danger Index. Rated as low-moderate (FDI 0-12), high (FDI 12-25), very high (FDI 25-50), severe (FDI 50-75), extreme (FDI ) or catastrophic (FDI >100). Fire Intensity The rate of energy output per unit length of fire front, usually measured in kilowatts per metre. It is a function of the heat yield of the fuel (H), the dry weight of the fuel consumed (W), and the forward rate of spread of the fire (R) i.e. I = HWR. Fuel break Synonymous with firebreak ; any natural or constructed change in fuel characteristics, which affects fire behaviour so that fires burning into them can more readily be controlled. Fuel breaks will not stop a major bushfire but provide a fire control line from which to suppress a fire. Fuel Load The oven-dry weight of fine fuel per unit area. Commonly expressed as tonnes per hectare. (also known as fuel loading). 9

10 Fuel Structure The quantity and type of fuel at different heights above the ground, usually separated into the following strata; surface, near surface, elevated and canopy. Where trees are present bark fuel is also included. In forests and woodlands the canopy fuels are normally left out of fuel assessments, but are included in shrublands and heathlands where they are the equivalent of elevated fuels in forests. Hazard Reduction Reduction of the average fine fuel load over an area by burning (planned burn or wildfire), chemical, mechanical, or manual means. Minimum Fuel Conditions A condition where fine fuels are minimised to the extent that the passage of a fire will be prevented or severely restricted. This generally requires the removal of dead fine fuel and control of live fuel, breaks in the continuity of any fuel, maintenance of a high moisture content in vegetation, or replacement of vegetation with roads, paths, etc. Planned Burn (Synonymous with prescribed fire, controlled burn, prescription burn, scheduled fire or management burn) The controlled application of fire under specified environmental conditions to a predetermined area, and at the time, intensity, and rate of spread required to attain planned resource management objectives. It is undertaken in specified environmental conditions. Spot Fire Isolated fire started ahead of the main fire by sparks, embers, or other ignited material carried by the wind, sometimes to a distance of several kilometres. Spotting Behaviour of a fire producing sparks or embers that are carried by the wind and start new fires beyond the zone of direct ignition by the main fire. 10