Fire! Fire! Fire!
Yes, Fire is your single biggest SHTF threat. All the planning in the world cannot stop your retreat from being engulfed in a blazing inferno. In California we are getting SLAMMED by fires. I am about 50 miles away from the closest fire but the air is still brown and smokey and you can smell it everywhere.
The one by me was started by a good ole-fashion, mother-nature-supplied lighting storm! But during a disaster the possible sources of serious fires increase exponentially!!! Burst gas pipes or mains, blown transformers, power poles being knocked down, riots, people burning anything to stay warm and even general mischief can cause out of control fires. They can sweep through cities and towns as well as wooded isolated retreats.
There isn’t much you can do about post-apocalyptic fire. You need to be able to move out at a moments notice. Have back up locations set. They don’t need to be stocked but KNOW where you are going in advance. Keep the bug-out bags stocked and be ready to roll.
To help save your house you may want to try to form a make-shift local fire brigade. Everyone in the neighborhood agrees that no matter who’s house is hit you all band together to fight it because ultimately you are preventing the fire from spreading to their house too! You can form a standard bucket brigade, that is assuming that the water is still running, of course or someone has a pool that hasn’t been drained. You can check out this site on Home Firefighting. Some systems use pools and lakes. Pretty cool stuff but at a couple grand only the best equipped and well funded groups can afford them.
Never under estimate the power of fire!