I subscribe to a site called instructables which I won't get into here as you can look at it for yourself if you haven't seen it already. They email the lastest cool ideas people have come up with and one of them was a rebar and concrete dome garage a guy built.

He did a great job but made a few mistakes but for a garage it will be fine. After looking at it and reading though what he did, I believe he has come up with a very cheap and VERY do-able way to build an affordable underground bunker with NO special tools at all.

I think with three men and a little 2x4 bracing to help with holding rebar, you could build a great dome shell that's about 32 feet across and around 800 square feet for around $5000 and it will be VERY strong. If you had foam sprayed on it, that would raise the cost about $3000 but well worth it. Plus you could have the foam sprayed later on down the road before covering it up. If you don't want foam, there's other coatings that would keep it waterproof, but it wouldn't be as well insulated at all.

I was thinking of maybe start at the bottom and use some sort of roofing tar and while it's still sticky, stick some foam board to it. Aagain, do a little at a time and work as you get money until it is completely covered. I would add more roofing tar and maybe some heavy plastic over that before burying it though. Now it is insulated, waterproof and ready to carefully bury.

It's nice because you can actually build as you get a little cash and do it in small sections and a month or two later do a little more. I would not worry at all sticking this in the ground as long as you make a few small changes to what he did here.

Also, you can go cheaper if you want a bunker that's only 400 square feet instead of 800. It's just that if you do have to use this long term, living inside a sewer pipe with no room and a couple other people, you're just asking for trouble quickly. Something else, this is just the shell not walls, rooms, electric and plumbing, but again as time and money permit, you can add those things.

I think doing it yourself and watching for sales or even used appliances and around $12k, you would have a very nice one bathroom and two bedrooms with a small kitchen, livingroom, laundry, and some sort of air filter system. Now this is not going to have a Hollywood home look, but it would be a great place to survive in and affordable over time for most people.

http://www.instructables.com/id/Cement-Dome-Garage/

He didn't exactly come up with the idea.

There are litterly dozens of ways people have done this.

The latest I have seen is using what scalled "concrete canvas" that is inflated, sprayed with water, and it hardens into a dome structure.

You do know who you're talking to, right? 1BB is the Arfcom standing expert on concrete domes, underground or otherwise.

Good luck.

Thank you for sharing this 1BB
 

I say get a bunch of earth bags, A BIG TRUCK OF SAND.  Hire a couple sand bag grils. You will be the proud owner of a como bunker.

Yeah, I love his posts. I think I will see if I can find some of the huge picture threads...





 

Tag cause 1 Big Bunker is my EF Hutton.



 

hmm very interesting technique, I was looking at surplus parachutes for a bit, but this you could literally do by hand with 0 power, or more easily with a mixer and mortar sprayer (which I see monolithic has a version of now).

No inflation fan needed. A footing would be nice though . I suspect it does not matter much, but I wonder how much irregular variation from hemispherity affects strength?

Whats foam going for a bd foot now 1BB?

LOL I didnt even see the name, I just responded.  I have seen lots of his posts.  Oops.

Way to go asshole, now you ruined all our fun!  I figured we'd get at least 3 pages of BS of you trying to find some jerk way out of it.  Here you go and apologized, crap!

Hi  O_S_R

Foam is running around $1800 a set now which comes out to $0.60 a bd foot before labor. I would get at least 2.5 lbs foam since you're going to have 3 feet of earth on it and sticking this 3 feet underground I would do in a second.

Yes, no real power or any special tools needed so if you wanted to build something like this off grid and books, this is the way to go. Plus, it's a VERY forgiving way to build.

You're right, a footing with a ring beam running ALL the way around the dome is a must. He didn't have anything where his opening is. You actually need more rebar there to carry the load across an opening and he has none. Granted, it's just a garage, but still, do it right. I would put a two foot square footing with three runs of #5 rebar in it depending on how big you wanted to go. Anything under 1200 square feet of living area and underground three feet, will be fine. All rebar is 60 grade too. Also don't forget to put a mechanical lock in the footing so your wall has something to sit into and lock so it can't move once it's set up.

The other thing he did was he ran his rebar all on around 12-14 inch OC. He should have stayed at 12'' OC with #4 up to about 8' and then went 10'' OC with #3. You have to tighten up the spacing if you go with smaller rebar over head, and it's easier to run the smaller stuff when you're working over head. Although, if I was burying this underground, I would use #5 up to 8' to 10' and stay 12'' OC and then go to #4 and stay around 10'' OC.

I would also have 6-8 inch thick walls up to around 8 to 10 foot and then 4'' thick concrete from there on up to the top. That is if you're not going over around 16 foot tall dome. This will easily support 2000 pounds, or one ton per square foot so 3 feet of wet earth will be less than 20% of the max load it can support so if you or someone else parks on it, it won't matter at all. I would also make the door area 18'' thick for about 2' on either side of the door.

When covering the rebar, I would use and have used heavy chicken wire and then I would use chain link fence and wire tie it all right to the rebar. That would be good enough so long as you don't have soup for concrete and you did it in layers. You could do it by hand without a shotcrete pump. It will just take longer, but the price is right.

I've been reading on here today that a lot of people are looking at those shipping containers to bury. That's not a good idea at all. If you want to build something that's shaped like a shipping container, build this. You can build this in almost any shape that blows your hair back. Build it 12 feet, which is 4 feet wider than a SC and go as long as you want. At 12 feet wide, you're looking at about 30 feet from footing to footing creating the arch. That means it will cost about $80 per running foot to build yourself if it's 12 feet wide. Thats floor, footing, rebar, and concrete at a 7 bag mix for walls and the dome arch.

That's probably a little high, but if you built a 67 foot long 12 foot wide tunnel, that's 804 square feet of living area and will cost around $5,400 to build. Now add in what you want to make it a livable bunker, and I think you could be into it for $12,000 and no one would ever know it's been built and you have an actual bunker.

You could even widen it from 12 foot to say 16 foot and build it only 50 foot long. You keep it 12 foot wide for say 10 feet and then widen it to 16 feet or whatever you want. Basically you can do almost anything you want just so long as you maintain the basics of building a dome. So really any small variations won't be a big deal. Just make sure you stay at 33% or more, of the wide you're building. So if you have a 12 foot wide tunnel, add in 33% and you have a 16 foot arch and 6 to 8 foot wall on each side going straight up before the arch starts. The max height would be 12 feet tall in the middle.

A 16 foot wide tunnel would have a 22 foot arch and have a max height of 14 feet in the middle with walls going up 8 feet on each side before the arch starts. This is as low profile as I would go before you have to worry about snap buckling with it's max load. We're not even close to that max load number.

.60 cents a foot just for materials? guess the quote I got last year for 1.45 a foot installed wasnt that bad.
I still have the problem that I have enough cash to either buy land, or build but not both and I am throwing rent money away

Going to have to do something this summer even if it is living in a camper.

Damn states instituting build codes now too

They linear idea is interesting though... I assuming it would need some kind of rafter ties to prevent spreading?


How is your project plans going 1BB? still fighting for financing?

BigBunker1 - this is off topic, but what about woodpeckers boring into the foam. Laying?

They've been a problem for me on conventional bldgs with foam/stucco surfaces.

Not too fond of W-P's...

Yes, that's not too bad at all considering he's probably buying just a couple sets at a time and paying more for them. Take a semi load and it gets a little better but to be honest, not much. I was told EPA made them change their blowing agents to a more earth friendly type and it's raising the price along with oil prices. EPA isn't to blame as much as OPEC but we won't get off track here with that crap.

I'm not sure what you're talking about as far as having it spread, but I can tell you this, it won't spread. In some areas you may have trouble with the earth PUSHING in on your bunker, but no rafter will ever stop the power of the earth shifting. It will just push and push and push and crush anything in the ground. I've seen parts of Texas that's like this.

What happens is the ground dries up so bad that is cracks. When it cracks, dust and small bits of dirts fall into these cracks, and then when it rains, the ground wants to expand back to it's normal state. Well there's no extra room for that extra dirt and hydraulic pressure you're not going to stop and it pushes in basements and bunkers unless they're 50 foot thick of concrete and even then it still might.

I think if you put a very steep round dome underground, the earth MIGHT slip around and over it IF it's not too deep, but I sure wouldn't bet on it at all. All you can do is NOT have any flat surface like a basement wall where the expanding earth hits a stop, because it won't stop, it will push your basement in rafters or no rafters.

Now this isn't something to worry about in most places and a tunnel type bunker like this is not any different than any tunnel you drive through for the most part, and a whole lot better than a basement. Plus you're not going to be any deeper than say 3 feet at the top of the dome. That's enough for fallout plus the concrete.

I've actually been doing some drawing of a layout for a 12' wide and about 60 foot long bunker built like this. That size will give four people about 13 hours of air before the CO2 and moisture levels get too high. An adult needs at least 105 cubic feet of fresh air an hour. I always plan for at least 125 CF an hour, and for at least 12 hours of reserve air. My thinking was if everyone goes to bed and the fan stops, we don't die in our sleep. If you're in a small shelter, someone better be awake at all times to make sure that fans stays running, and we all know how well that always works out.



As far as my project, well I hate to say it but I've kind of sold out to the Chinese on it. Trust me when I say I've exhausted all options here. Basically what has happened over the past couple months was a wealthy man who lives here in the US and has a factory in China and employs over 12,000 Chinese, said he would fund the entire thing IF and ONLY IF I sold it to his Chinese friend at retail pricing and we split the profits. So, I decided to make it a very sweet deal and I got 10 acres of prime ocean front land in Hawaii because I figured not many Chinese have heard of where I wanted to build but even a bush woman from the outback has heard of Hawaii. Plus we will make over twice the money because it's Hawaii. Once I'm done there I will NEVER have to go through anything like this again, because I will have enough to build almost three more projects completely debt free.

The Chinese guy will make enough money off of it to pay for it in 17 years so it's a great deal for him and it gets me to where I want to be. I just wish I could have got an American to open their eyes and do it, but like my friend said, it's easier to work with the willing than it is to try and raise the dead, and he's right. He said he spent a few years trying to get the factories built here in the USA but after so long and fighting every .gov agency over a factory, he said he got tired it and wasting money and about that time he was made a great offer to go to China and open his factory there and he never looked back. He said you can spend years wasting your time here and get nothing done, or you can go where they want you and get things going in a matter of months and start enjoying life the way it should be enjoyed.

I have a very close friend in Hawaii who owns a large construction company and he is willing to work with me and build at cost so we can then build again in Hawaii with some of the profits, and we will split the monthly income so he and his family is set forever as well. So, I don't even have to buy anything to dig through that hard blue rock. He has everything we need but a shotcrete pump.







That's a good question, and one I get asked often, bit not woodpeckers. Most ask about mice and rodents making a home in the foam. I have never seen anything eat or chew on foam to any degree that it is hurting the insulating value. Rodents chew to wear down teeth and foam doesn't offer them that kind of return for their effort and as far as bedding, it's not that soft and what they would want in a nest. There's just too many good things out there that offer the rodents what they're looking for with little effort on their part, besides foam.

Be careful with the Chinese 1BB, my friend sold to a Chinese 1/2+ [forced to accept 49%] of his profitable [but mismanaged] company several yrs ago, against my advise when he asked it [and got mad when I answered].

He lost most everything almost immediately to those crooks who set his biz up perfectly to be stolen [the person who did this was long known to him and believed a friend] and this and the lawsuits that have financially broken him will probably kill him in the next 18 months.

If so they win.

He's living a daily nightmare.

He still has no common sense how he's handling this.

Don't trust ANYTHING  you're told and get what you're promised before you give them the keys.

Ever since starting my biz, when I became aware of these things, I've observed folks fall for what they think is a fantastic opportunity and get greedy / or let caution fly to the winds, and the walls collapse around them.

YMMV

Well I am glad you will be getting it off the ground.

Big scandal up here right now, the state housing authority has been spending over 200k per low income unit in frickin Maine....
I have been researching the local rental market, high vacancy rates, but low quality, and sky rocketing operating costs (old buildings, heating oil) will be changing things in the next few years I think.

Bigbunker1 - you're leaving the business?  I was thinking of a garage.

Was looking to do a 32 ft diameter dome and even have started excavating part of a hill with my tractor.   This is on a downhill slope then into a shallow valley then up to the back of my land.   Just concerned that the up hill portion of the dome will have a lot of dirt on top.  Probably 10 feet or so.   Definitely thinking the chickenwire/rebar/chainlink fense approach shown on the instuctables sight would be what I wanted to do.  Instead of fish net, I'll use chicken wire.  Could you share some plans?  Definitely would do full ring footer and top ring that he didn't do in the garage build.  

Here's my umm bad MS Paint job.

D05GTO
You can pile all the dirt you want on one side and it won't matter. I did that on two different domes. One was 32 foot and 22 feet tall I think. I can't remember exactly how tall it was but it was two floors. The second floor had a walk out to the upper side of the hill, and the bottom had a door going out the bottom side.

The other dome was 52 foot wide and 33 foot tall. It was three floors. Just half of it was underground and ALL the pressure was against the back side. It didn't matter. I did increase the shotcrete thickness just to make sure. I think I put in an extra 25 yards or so. I can't remember exactly, but it increased the wall thickness an extra 3 inches. I didn't need to but I wanted to. I mean I want it there in a few hundred years even though I'm gone.

I also drilled four holes five foot deep that are 24 inches wide along the back side and in about four feet from the ring beam. I built a rebar cage out of 60 grade #5 and tied it into the floor rebar and stuck it down in that hole lined with sonotube so no dirt fell into my concrete when we filled the hole. If your earth is soft, I suggest doing that as well. Those columns act like anchor points, It's not really needed with the way the footing it built, but again, I want it to be exactly where we built it in a few hundred years.


As far as what you drew up, there's nothing wrong with that, but I would go down 5 feet or so with columns like I said above. Maybe not 24'' but maybe 18'' and do five of them.

The ring beam is a must for sure. A 32' dome calls for four #4 runs of 60 grade or three runs of #5 and again 60 grade. If it was me, I would use the #4 because 60 grade #5 is a pain to bend in a 32' size circle. I would NOT use the crap you get at your box store. Call up a steel mill and order what you want and you want 60 grade. That crap they sell in the box stores is just to hang a garage sale sign on, plus it is too dang short. You want 20 and 30 foot sticks. If you need help with what you're wanting to do, just ask, I'd be happy to help you out.

Something else I would do is hide your vent tubes. PVC is cheap, so run it underground a hundred or more feet away and bring it up in some thick blackberry bushes or something. Even plant some stinging nettle around it so no one will find it to use it against you. If you're by your home, bring it up inside a fake down spout in your rain gutters on your home. Anything to keep people from seeing them and getting a bright idea.

If you have a manhole cover, label like they do for a septic system and make it out of concrete with rebar and a way to secure it from the inside. Few people will screw with anything labeled septic and dangerous or poisonous gases inside.

What plans were you asking for? The one I was talking about before was for a 12' wide and as long as you wanted bunker. I think I have an old one around here some where for a 32 foot dome with a loft. It was around 1100 square feet with the loft. If you want some help with ideas for a floor plan, I would love to help out doing that as well.

Is this going to be a shelter or an actual home and shelter all in one?



EXPY37
Oh I hear you buddy. There's been more lawyers than construction workers on this. My name doesn't leave the title until ALL the money that's owed me is in MY account. To be honest, I hope they don't pay me. I would rather keep it, but I know that's not going to happen. Oh well, like I said, it gets me to where I've been working towards. I've always said, if it was easy, everyone would be doing it.



4v50
No, not at all. I won't quit building just because things get hard. The harder things get the closer I am to breaking through or the evil one wouldn't be trying so hard to stop us now would he.

1_big_bunker. I read all of your post you ever written on here. LOL Been planning this for a long time.  This will be a secondary location and not our permenant home.  Well, maybe if it turns out good enough.  I'm trying to sell a house and it just doesn't want to get sold.  We are living on the payed for land in a 50X60 metal pole building that I have finished some on the inside.  Living room, kitchen, 2 bathrooms and 2 bedrooms, utility room.  Planned to live there awhile while I figure out another structure.  Wife decided that it was just to homey and didn't want to build a regular house or go back to our other one in a subdivision.  This was plenty for her.. hey, were else can you walk out the living room and work on the boat, truck, car in your other living room. LOL

This is probably 200 yards from the garage/house.  I do have a solar system with a Xantrex 4024 Hybrid inverter, 16 T105 batteries, Outback charge controller, but only 4-200 watt panels so far.  Was going to run conduit from the building down to the bunker for regular and emergency power.  Will end up probably setting up it's own system.  No worries about the vent pipe being seen. It's in the woods and there are tons of bushes to hide it in.  There will be another vent pipe along the entranceway and an tunnel made out of 3' covert pipe across the hillside but sill covered with 2' of dirt.  Will run sewer lines along this to a septic tank and drain field.    

Just any plans with some internal layouts to get an idea where to put things would be great.  I may have to scale back to the 12 x however deep I can manage to dig into the hillside with the backhoe approach.  

Thanks,
D

THoose are a few years old now  and very expensive If I remember correctly

yeah those are stupid. nothing to say you couldnt build it yourself.

Ferrocement seems to be common in the developing world.

There appears to be many ways to arrive at similar ends. The metal/wire form that this thread was started about. The permanent airform monolithic uses (or a homemade or fabric version). A temporay ecoshell which you must put the foam on outside later and then cover with something to protect the foam.

youtube of an ecoshell sprayed in foam.

now I really wish the basalt rebar would be more commonly adopted. I really want to see engineering calculations on the ecoshell monolithic built with basalt twine.
youtube video of basalt twine
third world ecoshell contruction by hand

I don't know the specs on that stuff, but I honestly don't see why it won't work and last long enough for everyone to have no clue who originally built it. Just look at the Pantheon Dome in Rome. It was finished in 126 AD and it's still in use today. They did not have rebar, they used ropes of vitreous china for reinforcement and thicker walls. There's no sign of it going anywhere even after almost 1900 years. Too bad we don't build homes that last that long today.........well some of us do.

I remember 10 or 12 years ago a friend of mine and I were talking to some politician in Florida about building all domes after a hurricane came through. He listened to us and after we gave our little talk about domes to him, he said, well what do you fix or replace after a storm? We said maybe a broken window or something but there's nothing to replace. He looked at us and said, well that will never work here. He said if there's nothing to fix after a storm, what will my construction companies do for work? You will put them out of work, and we won't make money. ............

http://www.monolithic.com/stories/the-pantheon-rome-126-ad






You read all my posts? Heck I don't even read all my posts.  

It took me a while to find that 32 footer I was telling you about but I finally did. It was something a friend of mine and I were kicking around a few years back for he and his family. I included the floor plan we started with from Monolithic and how we made our adjustments to it.

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The first floor below is how we decided to lay things out. We moved the walls to give more room in the living room and to give more support for the second floor which will be for all the storage or at least the bulk of it. The little square between the tub and toilet is a stacked washer and dryer that was moved to make room for the gen room off of the kitchen.

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The second floor is where he wanted to come in from a hiden hatch on the surface using a steel ladder.

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Here's just a cut away view from the living room. The kitchen is open over the stairs so you can look into the living room, and the gen set door is at the back of the kitchen. The only thing we did not draw in at the time was where he wanted his garbage chute and outside container to hold it. That's one of two things I always see bunkers missing, where are you going to take the trash out to, and how are you going to wash cloths? The other thing is what will you do if someone dies in the bunker and you can't leave it because of NBC? I mean how many people are on meds that if they don't have them for any length of time, they die. Then what? That's what the cold garbage container is for.

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Here's what I was kinda kicking around for the cheap way of building underground using the no special tools way of construction. Yes, I believe in having ALL life support systems inside the bunker and in my control at all times. If you leave anything outside the bunker even in another building, at some point someone will take it. It's not that hard to have a gen set and fuel safely inside the bunker. It's diesel, not gasoline so it's no different than having the fuel tanks in your basement that ran your furnace in the winter. The other reason I have it inside is so you can have a water to water heat exchanger and your diesel will heat all you water in your water heater tank.  

When you start the gen set to charge batteries, you're making hot water as well and everyone can take a shower and do laundry, all while keeping the gen set cool at the sametime. All water is within a very small area so runs are short as well as in floor plumbing. I like to put the bathroom way back for privacy as well as someones rotten ass. No one wants to be taking a dump behind a door that's off the living room.

The other thing I didn't draw in was how we have fans that suck hot air from the gen set room and blow it through underground cheap plastic pipe. It cools that air and brings it back into the gen set room. A 7kwh gen set needs about 225 cubic feet of air movenment every minute to keep it at operating temps, plus the liquid coolant. It's A LOT harder to draw that in here than it is to install it, and it's CHEAP to install, and it works great.

You can also see what I was talking about as far as a place to dump your trash and you will have trash and you'll need a place to put it if you can't go outside. That container is behind three doors as well. You can say you won't have trash but you will. You're not leaving anything on the shelves in your home if you head into the bunker, and that food is not packaged for bunker living and generate little waste. What are you going to do with plastic bottles and glass jars and all those steel cans? Even after smashing them, they have to go some where.

Something else I think is VERY cool is what a friend of mine did with his gen set. He took a heater core out of some vehicle, and he installed it in his cloths dryer. Now that 192 degree coolant from the engine is drying his cloths after they're washed. Just another way of getting every last bit of use out of diesel fuel and being able to run a smaller gen set because you don't need the larger sets because you're not using 240v.

I really like this little diesel gen set. It isn't cheap at all, but it is very small, puts out 5.5kwh and uses less than a half gallon of fuel an hour. Plus it has a huge oil pan and hold 5 full quarts. I would get it without the radiator and use the heat exchanger and water tank like I said before.

http://www.hardydiesel.com/kubota-generators/kubota-x-gen-micro-diesel-generators.html

For me, I came up with 540 gallons of fuel based on the following:

Water pump.............................................1000w
Air Filter...................................................6000w
Lights.......................................................2400w
Refrigerator..............................................2000w
Stove........................................................2000w
Microwave..................................................200w
Coffe Maker..............................................1500w
Waser and Dryer.......................................1000w
On Demand water heater under sink............500w
Misc...........................................................3000w
Total............................................................................18,600 watts a day

Misc as in TV, video games, clocks, music, computer, ham radio, those sort of things.

With a 5.5kwh gen set, that's a run time of just under 3.4 hours with a consumption rate of a half gallon an hour or 1.7 gallons a day. That comes out to about 317 days of fuel and you said you had solar panels, so with those, think you could stretch that fuel to last a full year if need be. Plus I have some of those items pretty high as far as wattage used, but I'm a big fan of being over prepared. That on demand under sink water heater is for the kitchen sink. I think it would just be much easier to have hot water right away instead of running water until it gets hot, but that's just me. Those are cheap and easy to install.

I would not use any propane or any open flame in a bunker at all. It uses oxygen and I'm just not comfortable with open flames in a shelter plus I can make electricity but not NG or propane. The diesel gets all its O2 from outside, and does not use any filtered air from inside the shelter. Another thing that isn't shown is how we made vents from room to room so there's air flow and where it would exhaust to outside. Which would be in the get set room and also the bathroom. I like to put the airfilter in a place where we can keep an eye on it, and also where others are incase the motor goes out and we have to pump it manually. You really don't want to stick someone back by the storage area all by themselves pumping that thing. At least they can watch TV while pumping it and everyone can take turns.

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This is just a continuation of the tunnel above but with the bed turned a different way in bedroom 2 and an idea for a pet room and a place for them to go. I know some think bedrooms are not needed but if you're in there any length of time, everyone will want their own little space if at all possible. The cost of that wall will be worth every penny if you ever need a long term shelter.

Now this is really a nice decked out shelter, but it's a shelter that you can build to become this over time as money becomes available. No you don't need walls right away, but you can have some sort of kitchen and bath and the rest is open bay. Then add in what you feel you need for your family. Once the main structure is built, you can do what you want on the inside on your time schedule, but you really have to have a plan and a reason for everything you do from beginning to end.

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Interasting...

That layout works for me - even if it was not underground - tho the secondary bedroom would have been nicer if it was a wee bit larger.

With a Chinese economic slow-down, it might be cheaper to just buy and have installed large box culvert:
http://www.rinkerpipe.com/TechnicalInformation/drawings/PDF/013.pdf

Tag

no way on the box culvert. Domestic ones are rediculously expensive, and I cant imaginge the tranpost costs on importing them

ahh my build is in sight, getting property transfer sorted out now, deciding on siting. Pricing things now, may end up going with drystacked and filled block with exterior sprayfoam or just a small cabin build at first as we are throwing money away renting.

did see a arch metal building for sale on craigslist, thinking I could assemble, sprayfoam and then spray it into a concrete arch maybe...

Have to do lots of math.....

and talk the fiance into living in a camper for a while

hmm looking at getting something like this, having 3 inches of foam applied and then concreting the interior....

metal quonset hut

Shotcrete for the interior?

I think 1_big_bunker had mentioned applying foam to underground domes at the beginning of this thread. I had read Cresson Kearny's "Nuclear War Survival Skills" where he emphasizes that underground bunkers get hot quickly and emphasizes adequate ventilation. I wonder why it would be desirable to spray and underground dome with foam if overheating is such a problem. Certainly, waterproofing would be desirable; however, not so sure about insulation even in cool climates.

Domes should be the strongest possible underground shelter though and I really appreciate his posting all the other information. Thanks!

I think bunkers aren't much different than underground root cellars and those stay very cool in reasonable climates even in the summer.

Now if the shelter were full of heat emitting people I can see the temp rising, but not by much unless folks were packed inside like sardines.

Keeping warm seems to be a bigger issue than being too warm.

With all that insulation anything electronic would help increase the temp as well, even if you are only using it when the gen-set's running.  Though any air pumped in will be cooled like he 1BigBunker mentioned for the gen-set air.  I wonder if there would be much possibility for passive airflow. Basically air vents at the top of the dome, and separate ones down near the floor.  The whole, "Hot air rises" thing...  

jim

This is precisely what I have been thinking about. "In theory" (everything is great "in theory"!) reduces the specialized labor and costs a little bit...no overpriced air form, and there are DIY foam kits. Then all you need is shotcrete. Tying in the end walls may be tricky.

I think even more than heat, is the build up of humidity...I don't know what the answer is...but all these 1BB threads, and all the crazy ones in the survival forums...just highlights for me the redundancy of building underground. Take the additional cost and complexity, throw it at solutions above ground...and you'll probably be happier!

Water table is probably the biggest single issue with these. I'm sure humidity is also a problem in places like Ga. In Co., not so much. If water table drives you above ground, so be it. Any above ground solution has a number of weaknesses though. It's hard to get adequate radiation shielding and hardly any blast protection if you're worried about nuclear threats. A Molotov cocktail is very simple to make and very, very hard to defend against above ground. An underground shelter's weakness is the air vents. Rather than trying to conceal them with thorny bushes, it might be better to put them below grade and fill the area with grapefruit sized rocks. This will still allow air exchange and are much better concealed. Thorny bushes can be burnt or blown away by a blast wave.

shameless bump

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Why shotcrete a steel building?  I can understand the foam covering the outside... insulation... but is the shotcrete serving more than an esthetic function?

Beats me...  

Also, foaming the OUTSIDE of a Quonset makes no sense to me either...

1BigBunker, I don't know if you're still following this thread or not. I was hoping to find out how thick the walls would need to be if this were buried 10 feet underground measured from the top. In other words, ~30 foot deep hole. Would this require two layers of rebar?

Indeed

I didn't know what shotcrete was until I slobbered all over the big monolithic dome thread. My future retirement home will be 1BB inspired.



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I'm really interested in this as well for a retirement place (or earlier if I could financially swing it). I've quite happily been copying the floor plans out of this. I have a great deal of confidence that the man knows how to build domes. I do have two criticisms though.

First, he recommends keeping the air filter out in the open. If the threat is radiation, that filter is going to become quite radioactive in short order. Keeping it within the shelter is going to become a real problem very quickly. It should certainly be accessible; however, it is probably a much better idea to keep it along an entrance around a corner instead of direct line of sight to the main chamber. All entrances should have ate least one bend to avoid direct radiation coming down the entrance.

My second criticism is the three feet of overhead earth. It comes down to this. Is this a fallout shelter rated for only modest fallout, or is this a blast shelter which provides both fallout and blast protection? The intrinsic strength of an underground dome lends itself well to a blast shelter. In fact, there is no stronger structure. So, if all you need is a fallout shelter, you really don't need the strength of a dome. If you want a blast shelter, it does no good to survive the initial blast and then die a week later from the radiation because you only put 3 feet of dirt over it. A blast shelter is a lot more complex and includes things like blast valves on all air and sewage piping as well as blast doors.

Radius engineering has kindly posted a nice graph showing the estimated radiation inside the shelter with varying overhead earth cover. Note, this graph appears to be for the prompt radiation of the initial blast and not the fallout radiation. It is quite likely fallout radiation will be considerably less unless you are quite unlucky.

Reading the EMP info on that link [some of which might scramble the brains of our EMP 'experts' ] makes me wonder abt the accuracy of their nuclear radiation shielding reqm'ts.

They are in a competitive biz...  

Hi Gerri, I got an email saying someone had some questions about this, and they're good questions.

I looked at that web site you linked us to, and they did give us some good info there.

First, the reason I say three feet of earth is because in most cases, three feet is enough when you also take into account that the dome itself has around 10 inches of concrete in it as well, which increases your protection factor inside. Most people do not build a bunker too close to ground zero unless they have no choice, so they will automatically have time and distance on their side.

Now if you HAVE to build a bunker 1 mile from ground zero, three feet or so of earth will still be enough to protect you because at that close of a distance, the ground shock wave will be massive, and for anything to have a chance to survive, it will have to be equally massive. That means you don't have 10 inches of concrete, you have three FEET of concrete, plus the three FEET of earth between you and the outside world.

Now if every 5.5 inches of earth halves the rems coming in, then 3 inches of concrete should do about the same. Actually I believe it's 2.25 inches, but we will use 3 just to be safe. Now with three feet of concrete, that adds another 12 levels of protection above and beyond what the earth is giving you already. So go back to your chart, and start at three feet of earth and count down another 12 levels or so and see what you will be getting inside your shelter.

Just to give you an idea what kind of pressures we're talking here above ground, an EF-5 tornado with 300mph winds produce 404 pounds of force per square FOOT or about 2.8psi over pressure. In their chart they do not even begin to talk pressure until it is at 8psi or three times that of an EF-5 tornado.

Now if that's what's happening above ground in just plain air, what happens when we have a rippling force traveling through the ground coming at you? The closer you get the more rems you take in but also the more violent the forces you and your shelter are going to experience and the more massive you will need to build. A dome is designed to handle 2000 pounds per square FOOT or about 14psi so anything as far as a storm goes is easy to handle, but when you exchange moving earth coming at you instead of air, that's a game changer. I mean a 20 foot wall of water moving 25mph coming at you is very destuctive, so imagine what the ground will be doing to you near ground zero.

Other things to seriously consider is how you're storing supplies if you're that close to ground zero. It's onething if a roll of TP flies off a shelf, but another if glass jars of food start flying around. You just lost supplies. Just look at videos of earth quakes and you will see what I'm talking about. You can't just build a normal shelf and expect it to work when the violence start if you're that close or even in an earth quake area.

I hope I explained this clearly. It's late and I haven't been to bed yet.


As far as the filter goes, thats based off of the common filter most can afford when building a shelter. Plus it operates without electricity, so someone will have to be by itside pumping it and it's nice to be doing that around others instead of off all alone. Plus the manufacturer has designed it to be placed inside the shelter with you.

Here's what I'm talking about.
http://www.americansaferoom.com/blast-protected-complete-NBC-filtration-package.htm





Now as far as this question goes, what sizes are we talking here? If you're talking a tunnelish type of thing like in the link in my first post, then I wouldn't worry about it at all if you went 15-20 feet wide and as long as you wanted, and had #4 rebar, 60 grade and 12" on center up to the 8 foot mark, and then tighten the pattern up to 10" OC. I would do the floor at 12" OC with the same rebar, 60 grade #4 and do the ring beam with 60 grade #5 and do four runs of that around the ring beam.

Remember, rebar is for tension, and concrete is for compression. Piling on tons of dirt puts that structure in complete compression mode, so while adding more rebar won't hurt, it won't do much to help unless you're talking serious ground movement due to being at ground zero. Then you'll need it.

For the shotcrete I would do 12" from the floor to the 8 foot mark and then taper it to about 6" and keep the dome as a half sphere or close to it. You can flatten it out some if you want, but I wouldn't go less than 40% of your diameter. So if you were 20 feet wide, from the top of your wall and where the curve of the dome starts, I wouldn't go go any flatter than an 8 foot arch.

I would also seriously reconsider going down as deep as you're talking. It costs money to dig that deep, and if I explained myself clearly, you don't really need to. You won't be digging just that hole, men can not work in a 30 foot hole. It has to be tapered out and a road built down into it so trucks can pour the floor.......unless they won't be and you will do it yourself. In any case, it has to be tapered out or someone will die if a 30 foot dirt wall gives way.

1_BIG_BUNKER, thank you so much for your answers.

I totally agree that the radiation table they came up with is really just a best guess based on assumptions they've made. I might add to some of your thoughts regarding that table. First, they assume a surface burst. As you point out, that will move dirt around and would be completely unsurvivable if you are at or near ground zero. I'd expect surface bursts to be rare unless it's a terrorist using a railroad car or shipping container. It isn't worth it to live in a big city, near an airport with a 7,000 foot + runway, or near refineries for lots of reasons beyond just being a target for nuclear warfare.

All of these types of tables depend on knowing lots of variables. Is the weapon was surface or air burst? What size is the weapon? How far away? How much shielding? If the shielding includes dirt, what is the moisture content? After the prompt radiation from the initial blast, then you have to worry about the fallout. That depends on knowing the wind direction and all the upwind explosion details. Also, if it rains, the runoff might cause fallout accumulation nearby.

In other words, it really is too complicated to know with any certainty. The most useful conclusion I came to after looking at that table was the very bottom. If you go deep, it doesn't matter what the variables are. After 10 feet, it's all good.

That's why I was asking about adding a couple feet of earth on top. I was using the 32 foot wide, and 16 foot tall dome you posted when I was asking about construction details. It seems like this would need 16 feet to ceiling, 1 foot thick concrete, and 3 foot of earth for a total of a 20 foot hole. Probably another 2 or 3 feet to put in a footer and gravel bed for radon removal? If I wanted to add another 7 feet of dirt, I'd need about a 30 foot hole. I'm well aware there is a big risk of cave in. I really like Utah Shelter Systems web site; however, the picture midway down shows this nice vertical wall that I'm assuming is somewhere in the high Utah desert. Every time I see those pics, I'm thinking there is no way that could be dug that way most places even if the water table didn't prevent that depth. Whether I'm digging a 23 foot hole or 30 foot hole, either way, it's going to be a pain in the ass and expensive. I just don't know if it would be all that much more expensive or not. Would the specs you mentioned apply to the dome instead of the tunnel like structure as well?

Regarding the air filter, thanks for the link. I didn't know there was any American manufacturer of blast doors, blast valves, and ventilation systems. I suspect we may be talking about two different things. I agree with your approach of having the emergency hand pump located where everyone can help. The difference is the filter needs to be somewhere shielded. The filter will be catching contaminated particles which will be giving off a lot of radiation shortly after any explosion. It's not clear to me from the link what American Safe Room recommends. I can't tell from their website how they recommend the actual filter be installed.

Thanks you very much for posting so much great information here. I'm always on the lookout for your comments.

If you wanted to go down that deep, there's no problem doing so with the current engineering on the dome. It's designed to be buried that deep.

I'm a little short on time right now, but read this article about a dome buried 30' deep.
http://www.monolithic.com/stories/the-invisible-dome-home

I will try to get back online later this evening.

I read that article and a number of others there. In one, they recommend  5 feet of overhead dirt but don't attempt to explain why. What was really helpful was discovering the reason you and they recommend good insulation. They describe attempting to keep the inside wall temperature the same as the air temperature to avoid condensation. They simply increase the ventilation to keep the place cool. They also mention adding long underground uninsulated galvanized steel pipes to provide additional air cooling with drainage to remove condensation within the pipes. It's not so clear to me that the large diameter pipes they discuss are suitable to a bomb shelter as it seems like they would be difficult to close off.

Cresson Kearny in Nuclear War Survival Skills describes avoiding insulation because the shelter will overheat. I finally realized the difference is that Cresson Kearny's shelters are more expedient and meant for short term 3-21 day occupation. Cresson Kearny even describes an expedient Kearny Air Pump to provide ventilation.

Lastly, one of the articles describes having a larger footer to support additional load bearing required of an underground dome; but, they don't specify any details. Do you have any opinion regarding footer size?

Yes, you have to keep the concrete the same temp as the air in the bunker. If you don't, vapor drive will naturally happen and so will a musty smell like most basements have. I did write a longer post on that a while ago, so I won't do it again.

I wouldn't put in any large pipe coming out of a bunker. In fact, I wouldn't put any pipe straight up out of a bunker. I would run both inlet and outlet pipes to the side of the dome and come into and out of the dome by going under the floor. I would also put a "T" fitting into the pipe and come off that "T" and into the bunker. Then I would continue running the inlet pipe down and into some sewer rock for drainage. The bottom of the pipe would have a cap but with many many drain holes drilled into it.

This way if someone found your inlet or outlet pipe and wanted to pour something in on you, they can't. It just falls to the bottom of the pipe and is drained off away from your shelter.

As far as the pipe underground to cool and also remove moisture, that works, but it takes a lot more pipe than you would think. You also have to lay the pipe like sewer pipe and at the low spot, drill drainage holes and make sure to put sewer rock under it so it drains well. I place some foam over the top of the pipe and rock on the side of the pipe to help keep dirt from down into your drainage rock. Remember vapor drive, moisture goes from hot to cold, just like a cold beer on a hot summer day, all the moisture in the air will condensate on that cold bottle. Samething in that pipe, all the moisture in your shelter will want to go into that pipe and condensate on the pipe walls and flow to the lowest section and drain.
 
I built a 32' dome with a 2nd floor and we did PVC pipe but only did 70' underground. We put a fan pushing and a fan pulling air through that pipe. We could tell a difference, but not what we were looking for. So, to make a long story short, 120 feet works for most average underground size buildings, but a good rule of thumb, is to put in at least the same amount of pipe as the circumference of your bunker but add about 4 feet per side. So if you have a 32' circle add around 8 feet to that and you get 40 X 3.14 = 125 feet and you're sitting fat. Same for a square building.

Another thing we learned was that about 175 feet of 4" PVC pipe is about the max distance you can run and not have too much friction for air flow. You will need to go to 6" PVC pipe for longer runs or place a "Y" fitting in there and run two seperate pipes.

I hope I explained this all clearly.


One very nice feature with those NBC filters I linked you to, is that they have a bypass in them. Basically, you can once a month or whatever, you can turn on that NBC filters fan and flush out old air and keep it nice and fresh. The air flow without being filtered is HUGE. I like this feature A LOT. Once a month or if the news on TV starts sounding like things are going down hill, turn that on and freshen up the bunker while watching TV in your home and deciding your next step.

Don't hold my feet to the fire on this next part, because I drawing from a conversation I had with these guys a long time ago. Basically the filters have to meet a MIL SPEC war gas rating that says the carbon has to completely capture the partical within 1/4 of a second of contacting the filter, and hold it. These filters are not like what you have in your car where you can tap them on your hand and crap falls out and you throw them back into the aircleaner housing.

Also, the particals that are trapped that are radioactive, are not the type that contaminate. These can be washed off of you or any item, and the damage stops. I believe they said the radiation that really contaminates to the point that all equipment and anything that comes in contact with it was neutron radiation and he said that's mostly found in nuclear power plants and not military type weapons. If I'm screwed up as polio here, someone please step in an correct me so we have the finer points really understood. After talking to him about the filters and understood that it wasn't something to worry about, I didn't really care anymore and I don't waste my time trying to remember pointless things.

Also, my in coming air to the filter is NOT a straight line run. I did go over this a while back like the insulation post. It's also not PVC or galvanized steel. I use only stainless steel pipe. It doesn't burn, rust, or break down like plastics and rubber when in a chemical environment. Seriously, this is something that will last 100's of years underground, so don't cheap out on pipe for your life support side of things.


Now the footings will be engineered when the plans are drawn and everything is already known, like how deep you're going. I will say this though, make sure you pour a floor and footing together and have 1.5" rock and have a 9 bag mix for the footing section, and a 6 bag mix for the floor. A 9 bag mix will test out to around 13,000 psi concrete and will never give you any trouble underground. Plus the dome shell will be a 9 bag mix so why have a weaker footing?

I know this, if you put in a 2' wide and 3' deep footing on 12" to 18" compacted sand base, you will be able to build about anything up to around 3000sf of living area 10' underground measuring from the top of the dome. If you're looking at 1000sf or less, 1.5' wide by 2' deep will be fine.

You will need to run FOUR runs of 60 grade #5 rebar for anything under 1000sf of single level living area. Larger than that you will need five runs of it or four runs of #6 for single level living areas of under 3000sf or so.

Underground in the floors I run 60 grade #4 at 12" OC and make sure you chair it. Above ground I run it 18" OC. Above ground I pour a 6" floor and underground I do a 12" thick floor. I do this because I know I can put in heavy things like fuel tanks, gen sets that vibrate when running, and not have to worry about any problems.

I always spray a 3 pound foam one inch thick on the ground before pouring a floor and footings for an above ground dome. Underground, I spray a 3 pound foam around 3 inches thick. I also spray foam out from the footings about a foot. Then I spray foam from where it comes out from under the footings, and up the side of the footings and a couple feet up the dome. I spray this pretty thick, around 6" to 8" or so. I do this to make sure there is no way for the foam and concrete in the dome to be compromised and leak.


If you build something like in the first post in this thread, just follow the same figures and you will be more than fine. Once you have a better idea what you want as far as size wise, let me know, and I will call Monolithic and tell them what I'm planning and run my numbers past their chief engineer Larry, just to make sure. No sense being stupid or paying thousands of dollars for what we already know.

I've wanted to go earth-sheltered for over a decade now.
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