EEVblog Electronics Community Forum
General => General Technical Chat => Topic started by: SeanB on December 26, 2015, 06:28:58 pm
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Was watching Al Jazeera, and looking at the news saw a little article about 100 homes burnt in a fire.
http://www.channelnewsasia.com/news/asiapacific/more-than-100-homes-lost/2377808.html (http://www.channelnewsasia.com/news/asiapacific/more-than-100-homes-lost/2377808.html)
Just a query, as Australia has these fires pretty much every year in summer, and they always burn down houses. Why do the people not trim the trees overhanging the properties, and cut a fire break around the properties, so that you do not have those lovely inflammable green torches over the house to burn it.
As well a simple change to a tile roof ( like Dave has on his house) along with not using inflammable materials for the exterior walls and fittings should reduce the property damage considerably. Having a lovely Eucalyptus fire-bomb, or a Black Wattle ( both present here in South Africa, and both classed as class 1 invasive species, with a permit required to plant them on any place other than a permitted forestry plantation, and a cut on sight elsewhere order) hanging over a tar or other inflammable roof seems like utter stupidity, along with not requiring the cutting and maintenance of fire breaks and brush clearance.
Insurance companies probably would save a packet on these annual claims, as people would lose coverage for those dangerous practises which are currently covered by a tax on all. Just a simple change, and this would definitely save a lot of lives as well, by requiring people to have a fire proof room in each house to protect them if they do decide not to evacuate timeously. Requiring a fire resistant carport would help as well. Australia does have standards that include brick and concrete block construction, which would be simple to require for high risk areas as standard. Older houses can often be retrofitted to a less flammable standard.
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fire proof room in each house to protect them
That's a dangerous suggestion: even if you're protected from the heat, asphyxiation is a real possibility once the wildfire surrounds you. It's much better to just flee.
Your other suggestions seem quite reasonable though. I wonder however how much distance you need to have between the fire and a downwind house for the house to survive. I imagine that even if a brick house doesn't burn, heat will cause structural damage.
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I'm an urban dweller, but my understanding is that removing a single large tree near your house costs you something in the thousands of Australian dollars.
I imagine that even if a brick house doesn't burn, heat will cause structural damage.
Brick houses tend to have wooden frame roofing.
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I don't know what the regulations or requirements down here are for existing dwellings in the now deemed fire prone areas,I do know however that after the 2009 black Saturday fires everything changed in regards to building regulations and fire preventative measures, some people were not permitted to rebuild in the same location due to risk yet the previous dwelling may have been there for many years prior.
One close friend who was in the middle of constructing a house in the Kinglake area about the time of these horrendous fires suddenly found himself having to come up with tens of thousands more dollars for changes to the construction so as to comply with newly introduced building regulations, he also added a concrete bunker which may have been an optional extra.
I don't know how much those Erickson sky cranes cost each year to lease during fire season and I wouldn't even attempt to guess at the value of both the helicopters and the supplied crews, it does surprise me however that the last I heard we do not have any ourselves on permanent standby, surely we could either build or buy some of our own and they have been proven to be invaluable and saved many properties and I suspect many lives.
The crews of these flying angels in addition to all Country Fire Authority members are to be thanked and remembered for their generous efforts.
http://www.cfa.vic.gov.au/plan-prepare/building-planning-regulations/ (http://www.cfa.vic.gov.au/plan-prepare/building-planning-regulations/)
http://www.cfa.vic.gov.au/about/black-saturday/ (http://www.cfa.vic.gov.au/about/black-saturday/)
http://www.heraldsun.com.au/news/victoria/new-rules-to-allow-families-to-build-bunkers-in-fireprone-areas/story-fni0fit3-1226933815894 (http://www.heraldsun.com.au/news/victoria/new-rules-to-allow-families-to-build-bunkers-in-fireprone-areas/story-fni0fit3-1226933815894)
http://www.smh.com.au/environment/weather/time-to-buy-aircrane-helicopters-blue-mountains-mayor-20131103-2wuuk.html (http://www.smh.com.au/environment/weather/time-to-buy-aircrane-helicopters-blue-mountains-mayor-20131103-2wuuk.html)
http://www.heraldsun.com.au/news/victoria/fury-as-elvis-firefighting-chopper-replaced-by-smaller-craft/story-fni0fit3-1226724748415 (http://www.heraldsun.com.au/news/victoria/fury-as-elvis-firefighting-chopper-replaced-by-smaller-craft/story-fni0fit3-1226724748415)
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Meanwhile here in the UK, we have floods! 14C On Christmas Day, lots of rain, high winds.
This used to be a 200 year old pub: https://www.youtube.com/watch?v=nBOBEoRT1W0 (https://www.youtube.com/watch?v=nBOBEoRT1W0)
The main road not far from Farnell in Leeds has been closed due to the river Aire breaking it's banks. I seem to remember Farnell are next to the river and canal, so lets hope they are high enough up to avoid a deluge!
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Just a query, as Australia has these fires pretty much every year in summer, and they always burn down houses. Why do the people not trim the trees overhanging the properties, and cut a fire break around the properties, so that you do not have those lovely inflammable green torches over the house to burn it.
In a word: Government.
Local and State Government have tree preservation regulations that limit what a homeowner can legally do in the way of tree clearing. Here's an example of what one family went through a few years ago: http://www.smh.com.au/national/fined-for-illegal-clearing-family-now-feel-vindicated-20090212-85bd.html (http://www.smh.com.au/national/fined-for-illegal-clearing-family-now-feel-vindicated-20090212-85bd.html)
Since the 2009 fires, things have improved, but within the eternal triangle of Government, conservationists and landowners the battle continues.
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Just a query, as Australia has these fires pretty much every year in summer, and they always burn down houses. Why do the people not trim the trees overhanging the properties, and cut a fire break around the properties, so that you do not have those lovely inflammable green torches over the house to burn it.
As well a simple change to a tile roof ( like Dave has on his house) along with not using inflammable materials for the exterior walls and fittings should reduce the property damage considerably. Having a lovely Eucalyptus fire-bomb, or a Black Wattle ( both present here in South Africa, and both classed as class 1 invasive species, with a permit required to plant them on any place other than a permitted forestry plantation, and a cut on sight elsewhere order) hanging over a tar or other inflammable roof seems like utter stupidity, along with not requiring the cutting and maintenance of fire breaks and brush clearance.
What you have to bear in mind, is that these fires are complete and utter bastards.
The first part of the fire, which can travel at over 80 Km/h typically 'crowns' through the top of the Eucalypt trees, which contain highly flammable oils, which will evaporate in warmer weather (it is thought that the 'blue haze' which the Blue mountains are named after is due to Eucalyptus oil).
This part of the fire is extremely hot, think of burning vaporised fuel with the heat releasing more vapour.
The biggest danger from this part of the fire is the radiant heat, and to be blunt if you are in the open, and this passes over you, or even within less than 100 meters of you, the radiant heat will reach over 800 degrees centigrade, can melt aluminium and leave you with serious injuries or dead.
While the initial fire storm will only last between 5 and 20 minutes, building a house that can protect against it is not a trivial project. you need the outer layer to be non flammable, you also need to have no places for ember ingress as the intense heat will mean any wooden framing (say in your ceiling) is absolutely begging for even the slightest ignition source to set it alight, and finally you need a sprinkler system, and since there will be no AC mains it will need to run off a generator (usually diesel), in low oxygen conditions (the fire storm will be consuming plenty of oxygen) for over 1/2 an hour, of course you also need a water supply that will last for this period of time. Note in the ferocity of the fire storm, the sprinkler system is not extinguishing fire, as removing heat from the outside of your house.
Then you need to have cleared and/or have low flammability trees around your house.
Contrary to popular belief, in consultation with your local Rural Fire Service, you can get an "asset protection zone" defined around you house, in which vegetation can be legally cleared. Where people have got in trouble in the past - such as the example presented above, is in not bothering with the paper work, and then just waking up one morning and randomly deciding to bulldoze all the trees in sight....
The second part of the fire is when all the undergrowth and remaining fuel burns in the wake of the fire front, while not as hot or fast moving, this can include fires that smoulder before bursting into flame hours or even days later.
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One close friend who was in the middle of constructing a house in the Kinglake area about the time of these horrendous fires suddenly found himself having to come up with tens of thousands more dollars for changes to the construction so as to comply with newly introduced building regulations, he also added a concrete bunker which may have been an optional extra.
How does a concrete bunker help? How does anyone breath in such a bunker?
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Here is what its like to stand in front of a fire-storm
https://www.youtube.com/watch?v=F3dPlVvkIZ8 (https://www.youtube.com/watch?v=F3dPlVvkIZ8)
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How does a concrete bunker help? How does anyone breath in such a bunker?
Well, yes exactly, while some folk have been fortunate, other people have died, even in underground bunkers due to asphyxiation when the fires hit:
https://youtu.be/DBe9XumhYmk
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The reason these homes were lost because of bad engineering practices, tree hugging greenies, money hungry local government and irresponsible state government.
Most of these houses lost were built with timber frames, with timber fascias, timber trusses and even timber walls. Most of them were in bushy areas with little attention given to clearing away the natural fuel around them. They build them in extremely vulnerable areas filled with eucalyptus trees loaded with flammable oil. A fool's paradise.
In fire prone areas, timber framed house, timber walls and timber windows should be banned by legislation. Steel frames, solid brick, mud brick or Hebel should only be allowed. Roof trusses should only be metal. Windows should only be aluminium or steel framed. Curtains should not be flammable. Aluminium blinds can prevent radiant heat. Owners should be fined if there is an abundance of fuel around their homes.
Trees are an enemy, but not to halfwit greenies. Just drive up into the Dandenongs, and you can see evidence of greenies queuing up just waiting to be burnt to death in their timber homes concealed by eucalyptus trees and thick undergrowth.
Many councils fine home owners if they remove trees off their own properties without expensive permit and bureaucratic legislation. This is because greenies have infested our local governments, and there is money to be made with this crafty form of taxation. In one area not far from Melbourne, a home owner had illegally culled trees around his home and was facing $100,000 in fines by his crooked council. Soon after he removed the trees, in the Black Saturday fires every house in his street were destroyed except one - his.
I once built my own 40 square home in a rural area out of steel frame and solid brick. Any carpets were wool. Most floors were tiled. The insulation and sarking were fire proof. The fascias were steel. Pretty much there was nothing much to burn. All grass for at least 50 metres radius was kept very low, using livestock to eat it, or slashing it. Any flammable materials like spare timber, hay, petrol, was kept in a shed 100 metres away. They was plenty of water available in an emergency around the place, via town water and a reserve in a sump with a pump. There were no trees anywhere near the house on purpose. When I built the house, any trees near the house were culled. There was also a 3 metre wide concrete verandah floor surrounding the entire house. The verandah itself was made of steel and cement sheeting. None of this timber rubbish. My neighbours also had enough common sense to keep their grass low and trees scarce. Around 1995 a big bushfire in the hills came within 500 metres of our house. I was not concerned at all for our safety or that on my neighbours.
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As well a simple change to a tile roof ( like Dave has on his house) along with not using inflammable materials for the exterior walls and fittings should reduce the property damage considerably. Having a lovely Eucalyptus fire-bomb, or a Black Wattle ( both present here in South Africa, and both classed as class 1 invasive species, with a permit required to plant them on any place other than a permitted forestry plantation, and a cut on sight elsewhere order) hanging over a tar or other inflammable roof seems like utter stupidity, along with not requiring the cutting and maintenance of fire breaks and brush clearance.
I think you would find very few roofs with tar on them in Australia, or in fact any other flammable material. Nearly all houses have either concrete tile or corrugated iron roofs with timber frames.
New regulations make an attempt at forcing new homes to be at least resistive to a fire, however the tremendous heat in a raging bush fire will easily buckle steel, melt aluminium, and explode concrete blocks/bricks. The only way to make it really safe is to either cut all the trees down for 50-100m around the building or not allow building in those areas in the first place. neither of these approaches are palatable to governments or conservationists.
Local councils have a lot to answer for, however in NSW they introduced legislation to allow people to reduce the risk to their houses but it had to be watered down from what is required to something palatable and ended up as the 10/50 rule. You can cut trees that are closer than 10m and bushes up to 50m from your home (but not outbuildings?). Residents in the cities immediately went into overdrive cutting down every tree in sight until the legislation was changed to only be effective in bushfire prone declared areas. :scared: There are plenty of examples of people taking advantages of gaps in the law and razing every bit of vegetation on their land, so councils have been forced to react but unfortunately they seem to always want to legislate with one rule for everyone, rather than allowing for local conditions.
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As well a simple change to a tile roof ( like Dave has on his house) along with not using inflammable materials for the exterior walls and fittings should reduce the property damage considerably. Having a lovely Eucalyptus fire-bomb, or a Black Wattle ( both present here in South Africa, and both classed as class 1 invasive species, with a permit required to plant them on any place other than a permitted forestry plantation, and a cut on sight elsewhere order) hanging over a tar or other inflammable roof seems like utter stupidity, along with not requiring the cutting and maintenance of fire breaks and brush clearance.
I think you would find very few roofs with tar on them in Australia, or in fact any other flammable material. Nearly all houses have either concrete tile or corrugated iron roofs with timber frames.
New regulations make an attempt at forcing new homes to be at least resistive to a fire, however the tremendous heat in a raging bush fire will easily buckle steel, melt aluminium, and explode concrete blocks/bricks. The only way to make it really safe is to either cut all the trees down for 50-100m around the building or not allow building in those areas in the first place. neither of these approaches are palatable to governments or conservationists.
Local councils have a lot to answer for, however in NSW they introduced legislation to allow people to reduce the risk to their houses but it had to be watered down from what is required to something palatable and ended up as the 10/50 rule. You can cut trees that are closer than 10m and bushes up to 50m from your home (but not outbuildings?). Residents in the cities immediately went into overdrive cutting down every tree in sight until the legislation was changed to only be effective in bushfire prone declared areas. :scared: There are plenty of examples of people taking advantages of gaps in the law and razing every bit of vegetation on their land, so councils have been forced to react but unfortunately they seem to always want to legislate with one rule for everyone, rather than allowing for local conditions.
Good points, but timber trusses and fascias are dangerous in the bush. A common way house fires start in the bush is hot embers find their ways into gutters and then set alight the roof trusses via the fascias. Tiled roofs are also a problem, with small embers find their way into gaps in the roof. Sprinklers installed around the roof can provide some cheap insurance - turn them on as you evacuate.
I agree, cut all trees down 50-100m around. IMO, the only good trees near a house are fruit bearing trees. All the rest are weeds.
Where I live, you are not allowed to remove any tree anywhere from your own land without paying the local government for a $115 permit, and a $350 arborist's report, an essay on why you want to get rid of the tree, a copy of the title of your home, a plan of your house on the land, photos of the tree, numerous inspections, and a drawing of what approved tree you are going to replace it with and where, and other documentation. That applies not only to natives, but foreign trees as well. In a recent debate in the local council, the militant greenies successfully fought against home owners having the right to freely remove any tree without a permit.
A mate did the right thing and removed several eucalyptus trees at his home on Philip Island. After the trees were removed, the council came to inspect my friend's replacement saplings (the cheapest approved types he could find) and everything was signed off. Within 30 seconds of the council worker driving off around the corner, he kicked all the saplings out using his boot :-DD
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I remember years ago watching CNN when LA had the annual fires, and they cut to a scene of bare what used to be suburbia, with only chimneys left standing. In the middle of all this was a single house still intact. They went over to talk to the owner, a Korean engineer. CNN talking head asked him why his house was still there, and he replied " I thought everybody know wood burn". Brick house, plastered wall, tiled roof.
Yes, the wooden beams can burn, but you can make them thicker and clad the outer sections to reduce this, along with a flame retardant coating on them. Inside glass wool insulation under the tiles to reduce heat transfer through the tiles would help anyway with cooling, and placing some entry way brick baffling to reduce direct radiation, along with some white steel shutters for the windows, will also help to reduce the radiated energy input. You are not going for 24 hours fire resistant, you need at most 90 minutes as the flash front moves past you, then the residual can be tolerated. You probably will want however a large metal water tank ( or a few buried plastic ones) to supply water for a set of sprinklers under the eaves, and a battery powered pump to do misting of the edges to reduce the temperature. Steel piping there of course, the plastic will melt.
This is an annual thing, not a decadal thing, you really should plan for something like that, like people plan for holidays in advance.
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Fire regulations have been evolving. I've been looking to buy/build in a fire prone area and to build to modern fire standards can run at 25% of the build cost depending on the risk zoning.
More of you want to exceed the minimum standard and that's on top of 15% for bribing the local council.
The green fight has also been an ongoing issue. Areas like the blue mountains could be protected from large fires through proactive back burning. By the time these activities are approved the short window when conditions are suitable has often gone.
Most of the at risk housing stock is old buildings rather than new builds. When the flames are licking the windows there isn't much you can do.
J
Sent from my Nexus 5 using Tapatalk
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saw this a few months back on BBC website, fire resistant cypress trees (http://www.bbc.co.uk/news/science-environment-34116491)
maybe line/barriers of these trees could be grown to limit the extent of the fires
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Not far from me there are homes on the river which flood at least once a year and they've had it 3 times this year. They have been offered floodgates but wont accept them as they might reduce the value of their homes. They were going to install some form of flood defences on the effected stretch of river but again they fought against it as it would ruin the view. They tried to push a scheme that would flood almost 200 homes upstream (that have never had this problem) to protect their row of 10 houses (which have had this problem for at least 100 years) as those 200 homes aren't as valuable so they deserve it...
I can imagine in at least a few cases the same reasoning is true in Australia. Why reduce our risks of fire when the same things that increases the risk also increase the property value? I can also imagine they are protected from having to pay the full cost of insurance putting themselves at such increased risk should incur as people who chose to live on floodplains do here.
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I recently built in a bushfire prone area. In the state of New South Wales, we determine fire risk (and building requirements) and give it a BAL (Bushfire Attack Level) rating. Initially due to bush and trees on my block, the assessment came back at BAL-FZ (Flame Zone) which is the highest there is. This initially meant an added $60k to the cost of construction.
Since the new 10/50 Legislation was passed, now means those in a declared bushfire prone area are legally allowed to clear trees within 50 metres of a dwelling (whether it be yours or anyone elses) and scrub within 10 metres, if it's on your own land. So I cleared about 30 metres worth of trees and scrub based on measurements of the homes next door to my block and got that down to a more friendly BAL-19 (which is about "medium risk"). You can do this despite council requirements stating you need approvals or otherwise -- State law trumps local government law. I kept some trees but spaced far enough apart so that they weren't considered "bush" and did not contribute to the overall risk and BAL rating.
Having said that, if the bush/trees etc... aren't on your land, you can't touch it without the landowners permission, so those who back onto government owned land or national parks are out of luck and will have to construct according to the higher risk.
That said, having been a member of the volunteer fire brigade for over 7 years, houses are mainly lost due to bushfire because of complacency; Not clearing gutters, pruning or removing trees and other combustible vegetation, keeping flammable substances near homes etc... People leave things too late.