Crawlspace as fallout shelter?
Posted by purpleflask@reddit | preppers | View on Reddit | 36 comments
I live in a house with 3 floors, but no basement. We do have a crawl space that is about 4-5 feet tall, depending on where. Is that a logical place to build a fallout shelter or do the three floors above pose a risk? We are also situated atop a small hill so the sides of the crawl space are surrounded by earth, basically sunk below ground.
chris782@reddit
You'll still need to have some dense materials between you and your roof to protect from fallout if you are downwind of a target. Bricks between floor joists, lead sheets, steel plates, sand bags, water bladders all have different shielding properties. Steel, brick, and sand are what I would go with personally. Definitely add some supports and strengthen everything up so you don't get crushed. At that point you might as well rip out the floor and pour a slab of concrete though.
AnitaResPrep@reddit
Such a shield is oversized, or you have a massive amount (as snow, volcanic ash) of radioactive material on your roof - and anyways it will collapse.
chris782@reddit
Not true, speaking as a Nuclear and Radio-logical Weapons of Mass Destruction Specialist that lives next to several priority ground strike targets, you need more than the wood of a few floors and a roof to stop gamma radiation shining down on you. Even a small amount of fallout on your roof from a blast that same day will give you a lethal dose in a few hours. Halving thickness or brick is 2 inches, another 2 inches and you get quarter the dose, another 2 inches you get an eighth the dose, 2 more gets a 16th. That's still a lot of brick to get to a radiation protection factor of 100 that is recommended to be a "fallout shelter". There are many civil defense manuals on how to construct these small shelters in places like OP is asking about.
AnitaResPrep@reddit
Yes but most of these books are old and obsolete. We dont think and prepare the same way in Europe emergency /civil defense teams.
chris782@reddit
I guarantee that they do, what is outdated?. The science behind it doesn't change, thick dense materials are the only way to protect from gamma radiation. Any amount of fallout that lands on a roof within \~2 days of a blast is going to emit large amounts of gamma radiation and most people would not be protected, will receive a lethal dose, and then die. Except Switzerland and their 365,000 bunkers with room for their entire population. Germany is reconditioning their fallout shelters and building more. Here's a French slideshow on protection from radiation https://www.asn.fr/l-asn-informe/exposition-asn-irsn The UK material all says what everyone else is too. Poland is making as many bunkers as they can. If anything Europe has the most bunkers in the world and in many ways is more prepared for nuclear war than any other region. Doesn't change the fact that all the info in that manual is just as relevant today as it was in the 60's, in fact is more effective than the large centralized bunkers built in Europe. Small decentralized shelters in residential areas offer quicker access in case of an attack with todays ICBM's vs a fleet of bombers and having time to travel to a large shelter. And that's straight from a German report from the Federal Office of Civil Protection and Disaster Assistance (BBK). "For that reason, the government is planning to recommend that citizens should acquire cheap and easily available building materials to build safe rooms in their basements to protect themselves."
gilbert2gilbert@reddit
I'm in your crawl space right now. It's nice down here
SamWhittemore75@reddit
It rubs the lotion on its skin. It does this whenever it's told.
mendoza8731@reddit
It puts the lotion in the basket
hope-luminescence@reddit
"surrounded by earth" on the sides is what you want.
Can you put sandbags on the floor above the shelter spot? And move appliances, furniture, books, cordwood, and other junk there?
Can you figure out a place to use the bathroom, even if it's unpleasant?
CollectiveJohn@reddit
Crawl spaces are well ventilated to stop condensation. Inside your house would be better.
hope-luminescence@reddit
You want good ventilation.
funke75@reddit
what if your crawlspace is encapsolated?
lacroixanon@reddit
Then it wouldn't let fallout in but it also wouldn't let moisture out, so then you're counting on SHTF soon to justify the alternative property planning; bc unless you're in the desert you just signed the death warrant for the floor joists.
funke75@reddit
our encapsulation includes a barrier on the dirt floor, so it really doesn't let any moisture in.
Vagus_M@reddit
Against fallout, simply staying in the middle of the first floor would offer nearly as much distancing, and be easier to live in.
AnitaResPrep@reddit
If no blast risk, better to built a shelter in the middle of the house, WITH proper airfiltration (activated charcoal + HEPA)
chris782@reddit
All the manuals specifically mention not make a shelter in the middle of your basement as it is the least protected. A corner with the least amount of foundation protruding above the earths surface is going to be the most protected. Air filtration is low on the list of priorities for an small shelter inside of a residential building. Fallout is not a gas and will not float into your house and radon is not what we are worried about here, we need to stop the hard gamma that settles on outside surfaces like dust. There is literally a paragraph that says "What about the center of the basement?" and explains what I just said in this manual. Please stop spreading bad information.
https://orau.org/health-physics-museum/files/library/civil-defense/fallout-protection-for-homes-with-basements.pdf
r_frsradio_admin@reddit
Yes if the crawl space is below grade then it will offer significant protection from fallout. You may get a dose of radiation from above but it's still much better than being unprotected.
AnitaResPrep@reddit
Fall out is mostly dangerous when inhaled ingested.
OnTheEdgeOfFreedom@reddit
I'm trying to imagine a week in a space with a 5 foot ceiling. I think I'd go insane.
If you're actually worried, can you dig down 2 more feet? Being able to stand up, put in a portable potty you can get off on without hitting your head, etc would be worth it.
grey-matter6969@reddit
Irish Whiskey will cure you of your views.
OnTheEdgeOfFreedom@reddit
For a solid week?
jranso1709@reddit
This is the way
OnTheEdgeOfFreedom@reddit
Honestly... given that fallout at least means nuclear war, and might mean that EMPs were or will be used... yeah, I begin to see the logic.
HazMatsMan@reddit
If the walls of the crawl space are backed by earth, it may actually be somewhat more protected than the inside of the home. In addition to that, you get some additional distance and a little more material between you and any fallout on the roof. However, it's difficult to estimate how much additional protection.
I wouldn't be terribly concerned if the craw space isn't vapor-proof. It doesn't need to be to still provide protection as most of a shelterists dose will come from deposited fallout outside the shelter, and not fallout that "blows in" and/or is inhaled.
stu_pid_1@reddit
Sorry, it's a start but it's not very good.
You need air filtration and at least 50cm of concrete or a meter of earth between you and the fallout if you don't want to risk radiation issues.
The air filter is by far the most important, you can almost get away with a good particle filter and a decent carbon filter and wrap the whole things in steel or lead or beat of all put in another room with a thick wall to shield you.
Skalgrin@reddit
It's better to build one in your yard. It's not a bad place per se, but the risk of the house collapsing on your escape routes is too big. Sheltering in basement poses similar risk, but it's outweighed by "bunker already there". You have nothing in your crawlspace, build it in your yard.
starktargaryen75@reddit
Isn’t it great we have to worry about stuff like this?
TheKiltedPondGuy@reddit
Not great not terrible
SunLillyFairy@reddit
Regular crawl spaces are problematic as fallout shelters, IMO. Even with 3 floors, they won't have adequate shielding from gamma without reinforcement. Besides being uncomfortable, they are very hard to seal and then vent at a good level, often damp, hard to get stuff into, hard to create a toilet area, and there's a risk of collapse or getting stuck down there without completely reworking an entry/exit.
I think it is usually easier and safer to convert a garage (almost always directly on a slab), or some other room in the house, or construct a cement shed/shelter than it is to rework a standard crawl space.
Globalboy70@reddit
You need to be able to seal it off, air wise to prevent fallout (dust) contamination the first couple weeks.
murquiza@reddit
Why would it be better than the 1st floor? If the house above goes you will not be safe under. And if it doesn’t you will be better inside.
Fit_Acanthisitta_475@reddit
That’s pretty good, I would digger a 10x10 size room that can be staying up.
Femveratu@reddit
Maybe grab some sand bags to fill or pre fill w sand or earth to place on the floor above you just make sure it’s not too heavy etc to give you some additional shielding from any radiation emanating from the roof or the sides of the house up against it
-MomentoMori@reddit
Better than nothing, absolutely.
No-Garden8616@reddit
Fallout shelter - yes (RPF of 100 is feasible). General air raid (bomb) shelter - better than nothing. Survivability about 75%.