Homes are lost because of combustible fences and the location of wheelie bins and stored timber.
Wheelie bins burn out quite prolifically, and they are enough in themselves, if parked under a window or against a combustible facade, to be the reason why a house is lost.
If a fence falls over as it burns, for your typical urban house lot it'll strike about the centre of your window and break it, even if that's a toughened glass or BAL-40 window. That's something that isn't actually addressed in building regulations at all, but it is a very prevalent way that houses are lost.
Typical separations we see between neighbouring houses, or houses and sheds on the same property, or houses and sheds on neighbouring properties, when they're significantly less than 12m, say around the 6m range or less, then there is a very high chance that one house can burn its neighbour down.
In a fairly built-up environment, we've seen wood piles against fences that are sufficient to take out a neighbouring property, built at that normal setback of 900mm from a boundary. And that can be with a non-combustible fence or with a combustible fence in place.
CCA treated pine presents a significant fire risk.
Treated pine is simply not a compatible material in a Bushfire Prone Area, and I would suggest not putting it into the landscape, and to progressively phase it out of use on your property.
The CCA treatment that makes the pine resistant to rot and termites when used against earth, that process makes it even more readily ignitable and more likely to burn to completion than the pine that it started out as.
Well over 70% of the metal salt treatments that actually went into preserving that wood actually remain in the landscape as a green ash made up of toxic metal salts that ends up getting washed into the soil and is very bio persistent. So, it has toxic effects well after the fire, and is a particular risk for people attempting to clean up that area or to fossick through the wreckage.