While it is very good to be proactive about your family, you need to know the physical and even psychological dangers in poorly planned bunkers:
“.. Many harmful gases are heavier than air, and will collect in your bunker unless you take precautions.
Even if the gas itself can’t kill you, it will push out oxygen until you have nothing left to breathe, and that will kill you. Scenarios that people commonly prep for can involve gas release, like domestic unrest, war, and more.
Imagine pulling tear gas into your bunker. Then you should consider pandemic prep, if you want to use outside air you need a filter system. Or, you could consider gas leaks that wouldn’t normally merit a SHTF situation. A simple nearby propane leak, off-gassing from nearby septic tanks, or off-gassing from the soil itself, could all kill you…”
Please do your research before you sink $5K,$10K,20K and typically $40K or more in an underground structure AND more $ in the supplies you place in it. You do not want your good intentions to becomes some unintended consequences! The health of the people you love most is at stake.
From Backdoor Survival