5 Ways to Prepare Your Property for a Bushfire Part 2

Ken Walker

In the previous article, we provided a single bushfire scenario. As you could imagine the possibilities are endless and no two bushfires are the same. In this article, we will look at how to start preparing for the bushfire. Emergency planning specifically for your property. 

1. How complicated should preparations be?

In relation to setting up to protect your family and property from bushfire. It would be quite easy to spend many tens of thousands of dollars and still have your property burned down on a code red day. On the other hand, you could spend as little as four or five hundred dollars and think you have prepared well. Only to have your property burn down when the fire danger rating (FDR) was only rated high.

In the following image, there is a guide provided which puts a price on how much it may cost to protect your house for the different fire danger ratings. 

Disclaimer: Even though, we have researched and provided a base price for the different FDR’s. It is STG Fire Safety Training’s view only. STG Fire Safety Training does not guarantee that this report is without any omissions or errors and therefore disclaims any liability for any errors, loss or other consequence which may arise from the use of any information within this document.

Fire Danger Rating & Cost of Firefighting Infrastructure:

  1. High to Very High.  $5,000 to $15,000.
  2. Severe.                       $16,000 to $25,000.
  3. Extreme.                   $26,000 to $35,000.
  4. Code Red.                 $36,000 to $100,000 (depending on construction and risk)

You may be a little shocked at the prices and think that you could do it for far less. We intend to clarify the prices and indicate what the money would be spent on. You may already have some suitable equipment which could substantially reduce the cost. What costs all the money. Below is an incomplete list of what you would require.

Prices are estimates only.

  • A defendable area with fire-resistant plants (Estimate $500 to $3000).
  • A 40,000 to 50,000 water tank (metal or protected using dedicated sprays if plastic (Estimate $7000 to 12,000))
  • Two diesel twin stage pumps (one is a backup) capable of adequate pressure and flow or an electric pump powered by an electric diesel generator and a backup two-stage diesel firefighting pump ($2000 to $15000).
  • A simple ring main around the buildings you wish to protect ($1000 to $5000)
  • An appropriate amount of impact sprinklers and fittings strategically located throughout the defendable spaces ($500 to $2000)
  • A dedicated sprinkler system over each building to be protected ($2000 to $20,000).
  • Gutter protection and fire stopping around roof areas ($300 to $3000).
  • Closure of all spaces under buildings and decks ($300 to $5000).
  • Other firefighting equipment (extinguishers, knapsack, personal protective equipment etc) ($500 to $2000)

Optional:

  • Firefighting unit (pump and tank on a trailer ($1000 to $10,000)
  • In bushfire management zones (BMZ) if your building s a new house, there may be a requirement for a Bushfire Attack Level (BAL) assessment. This can add substantial cost to the house or business construction.

How to Prepare For a Bushfire Part One-03

2. Where to start with protection for your home.

As an example. a fire investigator starts the process of investigation some distance from where the expected fire origin is. Getting an understanding of the area and specific problems or inconsistent features. 

Standing well back from your home on the northern side. Notice the type of vegetation. Where are the main clearings, how close is the vegetation to the house, do you keep the lawns and grass area’s short, is there leaves and sticks under the trees or do you rake them up.

Maybe there is a slope leading right up to the house or is your property quite flat. If you live on top of a hill and there is bush all the way up the slope this is very problematic in relation to emergency planning. In this case, it is important to get advice from an experienced and qualified consultant or fire brigade officer.

Moving on, have a look at your neighbour’s property, has the available fuel been cleared. We suggest that you have at least 30 metres of defendable space around the structures that are to be protected. If you live on top of a hill space may need to be extended to 50m to 150m. This doesn’t mean there can be no vegetation in such space but does require only fire-resistant plants and shrubs.

We have another blog post relating to fire-resistant plants, shrubs and trees. It would pay to have a look at the post we have even provided a downloadable pdf list of fire-resistant plants. Some bushy fire-resistant plants can substantially reduce the number of burning embers that reach your home.  

Where environmental overlays restrict what you can clear. It would be important to either get a permit from the council to clear the defendable space or gather advice from an environmental consultant.

3. What to do with the defendable space.

Often when sprinkler systems are set up on and around buildings, the designers don’t put enough emphasis on wind speed. On an extreme or code red day you could expect wind speed up to and over 100km/h. 

If you were to direct a normal garden hose or even a normal fire hose into the wind on such a day. You would get all of the water back in your face. This isn’t all bad, we can use the wind to our advantage and set up impact sprinklers to pre-wet (pre-ember attack) the buildings and vegetation before a fire arrives. Just remember that the daytime temperature is probably going to be significant so water will need to be applied continuously.

This pre-wetting works to increase fuel moisture content and allows quicker wetting when the embers and heat increases as the fire approaches. By considering how you can use the wind to direct water into areas for greatest effect.

These impact style sprays would be positioned on the northern side of the building within the defendable space. They should be metal construction. if you use plastic piping it needs to be buried 600mm under the ground. Where the pipes leave the ground they would need to be metal.  

Coverage would need to see water sprays overlapping and appropriate flow rates used i.e. 19 litres/min at 350 kpa (guide only). If you calculate this water consumption you would see that one impact sprinkler would use 1140 litres per hour. When using the minimum two sprinklers the flow would be 2280 litres per hour.

It is recommended by the authorities that you have enough water to operate for 2 hours. We suggest at least 3 hours of operation. As often when the smoke becomes thick property owners start their fire systems and use less water test the system, which is an important thing to do.

It would be possible to write a 10,000-word fact sheet on this alone so we will discuss some of the more general issues relating to design in the next couple of articles.

4. Other issues in the defendable space.

Portable fire hoses and extinguishers are a great asset when a fire is approaching or has passed by. You can use them to put out a spot fire. Furthermore, keeping corners, where burning embers may accumulate, wet and free of burning material. 

A fire hose should be able to reach every part of the defendable space around the house. So a simple type of ring main is ideal. If you have up to three lengths of the hose connected directly to a fire pump that is fine. Again it must be able to reach every part of the defendable space. Any more hoses will reduce efficiency due to friction loss through the hose. 

5. What is the ring main?

It is a series of buried pipes (600mm) that create a ring around your house. At predetermined intervals, there is a riser connected to a valve (tap) for a fire hose. They are very versatile and will reduce the amount of hose you will need per connection. A pump would be fitted and supply water to the ring main.

Also, the impact sprinkler system would be fitted to this ring main. Each of the outlets needs to be controllable. Just in case you blow a hose or some other fault occurs in the system. It would be advantageous to have a plumber fit this system, but if you do the appropriate amount of research and planning there is no reason why it couldn’t be done by yourself. 

Remember if you are linking it into the reticulated mains supply a registered plumber must complete the work. Therefore, if you complete the work yourself it must be a stand-alone system.

In conclusion.

We have looked at some of the planning issues here which can seem quite complex. The significance of defendable space cannot be overemphasized and must be considered in your plans. I.e. Large trees hanging over houses or in close proximity are very problematic. In the next couple of articles, we will bring this all together and hopefully provide you with an ability to start the planning process.

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