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 Post subject: Underground Shelter Roofing
PostPosted: Tue Feb 07, 2012 2:58 am 
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Location: Maryland
I have been doing research on building an underground storage area/shelter. I am thinking a wood frame along the lines of 10 feet wide, 15 feet long, and 10 feet high. Taking this frame and basically burying it (of couse theres more to the weatherproofing and flooring etc). With these kinds of dimensions I understand that the earth's pressure on the roof will cause need for support from beams. I am curious what kind of roof would be best in this situation. I want there to be three feet of earth above, is this possible without causing too much pressure on the roof? Anyone have any insight on what method, style, and material to make this roofing out of? I have read about dome shaped roofing, or cement roofing, or a basic flat wooden roof with support beams every "X" feet in the middle of the shelter. I was hoping to avoid the beams in the center of the shelter. Any insight on this would be fantastic! Thank You for your help in advance.


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 Post subject: Re: Underground Shelter Roofing
PostPosted: Tue Feb 07, 2012 4:09 am 
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Concrete dome would be best. In my opinion.


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 Post subject: Re: Underground Shelter Roofing
PostPosted: Tue Feb 07, 2012 4:33 am 
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Very 2012esque

Joined: Tue Feb 24, 2009 6:33 am
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Location: Maryland
Any idea on what kind of construction plan you would need for that? I am handy with my hands but I don't work with concrete much. Not sure how to create a domed concrete structure without cracking etc :P


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 Post subject: Re: Underground Shelter Roofing
PostPosted: Tue Feb 07, 2012 4:41 am 
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Very 2012esque

Joined: Tue Feb 24, 2009 6:33 am
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Location: Maryland
Also with a wooden frame, I would not be able to do a concrete dome roof right? I cannot imagine a wooden frame holding the weight of the earth as well as a concrete domed roof. Correct?


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 Post subject: Re: Underground Shelter Roofing
PostPosted: Tue Feb 07, 2012 4:48 am 
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Concrete is the way to go. Either domed, or a traditional bunker design, of a giant culvert pipe, or poured over an existing structure like Ark II in Canada did (if my memory serves me correctly).


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 Post subject: Re: Underground Shelter Roofing
PostPosted: Wed Feb 08, 2012 3:20 pm 
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Concrete is a very good option however very costly, having to shore up the ceiling properly so that it won't collaspe while pouring the concrete is a major feat iitself.
I built a bunker or shelter partially in the ground and made the whole thing out of 44" x 19' steel pallet racks, including the over head. I had to cut up the pallet racks for some parts and other parts I left whole. I was thinking that you could use pallet racks for your overhead. You will have to space them appropriately and to have proper support underneath, but its an option to consider.
Here's some pics to view it.
http://s1202.photobucket.com/albums/bb3 ... 0ce718.pbw


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 Post subject: Re: Underground Shelter Roofing
PostPosted: Fri Feb 24, 2012 3:55 am 
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The dome or curved roof is the way to go. If you have strong side walls/foundation that the dome or curved roof sits on, the weight is placed on the walls/foundation. The last one I built was under 4 feet of dirt, 12" of fiber reinforced 4000# concrete with 1/2 "rebar and had another foot of dirt on top of that for grass. When I poured my patio next to it, the full concrete truck back up on the dome before I could say anything. It held and I filled in the tire ruts when he left. I was impressed. A simple solution was my first underground adventure and I buried a 10,000 gallon fuel tank. 21' Long x 10' tall/round. Dug a hole and dropped it in. 4" Vents on top, cut a door on the end and buried it. RangerRick










joshm1 wrote:
I have been doing research on building an underground storage area/shelter. I am thinking a wood frame along the lines of 10 feet wide, 15 feet long, and 10 feet high. Taking this frame and basically burying it (of couse theres more to the weatherproofing and flooring etc). With these kinds of dimensions I understand that the earth's pressure on the roof will cause need for support from beams. I am curious what kind of roof would be best in this situation. I want there to be three feet of earth above, is this possible without causing too much pressure on the roof? Anyone have any insight on what method, style, and material to make this roofing out of? I have read about dome shaped roofing, or cement roofing, or a basic flat wooden roof with support beams every "X" feet in the middle of the shelter. I was hoping to avoid the beams in the center of the shelter. Any insight on this would be fantastic! Thank You for your help in advance.


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 Post subject: Re: Underground Shelter Roofing
PostPosted: Fri Feb 24, 2012 4:51 am 
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Joined: Wed Feb 08, 2012 3:23 pm
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metal beam support would be your next consideration. would do just as good a job if done properly. :roll:


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 Post subject: Re: Underground Shelter Roofing
PostPosted: Sat Feb 25, 2012 12:17 pm 
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Why not an A frame style roof

The angle will help with water runoff and aid in strength for the width of your bunker.

I believe to stay away from steel due to the increased possibility lightning strikes.

A bit of lead lining may not go astray 8)


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 Post subject: Re: Underground Shelter Roofing
PostPosted: Sat Feb 25, 2012 12:34 pm 
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Definitely a concrete domed structure is the way to go. It's self reinforcing and offers better protection from surface danger. Radiated liquids, fallout, etc..It's actually easier and cheaper to build. There are companies that specialize in building domed structures. Doing it yourself would require knowledge on creating the cast and pouring the concrete. a geodescent dome also works and is far easier to cast and assemble.

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 Post subject: Re: Underground Shelter Roofing
PostPosted: Sat Feb 25, 2012 6:26 pm 
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Location: NE Oklahoma
A company in Texas was making concrete domed buildings using the shot-Crete method. They would inflate a dome of coated canvas material, put reinforcing wire and re-bar structure inside the inflated dome, then shot-Crete it from the inside starting at the bottom and working up. They were making huge domes this way.


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 Post subject: Re: Underground Shelter Roofing
PostPosted: Tue Mar 13, 2012 7:47 am 
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chucktrick wrote:
Why not an A frame style roof

The angle will help with water runoff and aid in strength for the width of your bunker.




This is all you need.

I've noticed that a MAJOR habit on this forum is to completely ignore the question, and give suggestions of how the person posting would do it, rather than actually help with what you're doing.

Simple fact is, the weight isn't such a major concern, as long as you have it distributed properly. Mankind has been building these things since long before the advent of concrete, and if you're only going two to four feet down, this would be just fine. Just build'er solid, and keep it simple. A good 90 degree angle, using 2''x4'' with a 6'' gap between each, and a good piece of plywood over top will hold up just fine (this is probably overkill even.) as long as you have a good beam to hold the weight at the top and the bottom. It's simple geometry. Honestly, the average house in northern regions could probably hold a good foot of soil on top without any worry, as they're designed to have a few feet of snow on them... which mind you, can weigh more than dirt with some melt and freeze going on. As for support beams, if you want something bigger than a root cellar, you're going to build this a lot like a house. The only difference is that you'll need a bulkier frame, and will need a strong base to support the sides. You might also consider just making the whole thing a triangle instead of a box with a triangular roof. (This wouldn't be noticed if you built it wide enough, since the sides could be entirely partitioned off for storage space, leaving you with a rather standard blocky living space that is so popular in modern construction.) Remember, this is simply an issue of directing the weight along the structure, and accounting for compressional forces. Also, treat the entry-way just like you would when installing a window on a structural wall. As long as you shore up everything to a standard of double what you would in an above ground construction, you'll probably be fine.

The main concern with wood construction will really be moisture. Moisture will rot and soften the wood, and not just what seeps out from the earth, but what comes from anything stored inside. For this, I don't really know what to tell you, as most of my experience in underground construction has been either simple storage spaces and getaways out in the woods, made out of local material and made to last maybe a decade or two with upkeep, or old random metal containers and scrap, welded up. But as long as you give good drainage around the site (gravel, sand, and such) and waterproof the outside fine, you could probably get off with a low-power dehumidifier running inside, just like you'd put in your basement.


Now, can we see more helpful posts that actually aim to answer the questions at hand, rather than just "OMG I wants a dome! BUILD A DOME! He should totally forget whatever he's planning to do, that's actually within his own ability, and cost range, and use our idea instead." so people can actually get somewhere? Also, if you guys are really considering a SHTF scenario, why in all hell would you have something built for you, that you personally won't be able to upkeep without resources that are only available through industrialized society? What are you going to do when your concrete starts to crumble, and you don't have any available to patch it up? This guy can just go cut down a tree, mill a piece of timber, go back inside and brace the structure up... cut out the bad wood, replace it, then remove the bracing. Like it or not, if you can't be self reliant in your plans, they're doomed from the start.

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 Post subject: Re: Underground Shelter Roofing
PostPosted: Wed May 09, 2012 2:46 pm 
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Joined: Tue May 08, 2012 2:31 pm
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The biggest thing I notice is no one has mentioed the type of soil not just the roof but the sides becaus of the pressure pushing in .The tighter the sheltor in the hole the better.This if you using wood and if you us cement there isnt to much to worry.


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 Post subject: Re: Underground Shelter Roofing
PostPosted: Sat Jun 23, 2012 5:54 am 
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I think, it's better to have a strong base and concrete roof.


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 Post subject: Re: Underground Shelter Roofing
PostPosted: Thu Oct 18, 2012 1:15 pm 
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Location: Central Florida, USA
hi all 8)
not everyone has unlimited supply of $$$ to build a concrete structure with building supplies as expensive as they are today. I found a 400 dollar covered 28ft trailer and 28ft shipping container for 500 dollars to do the trick. A little digging, welding and some roof coating and shes a nice 2 bdroom 1 bath home with lots of storage. Depends on how much soil you decide to bury it. But a 4x4 frame into the ground surrounding it and slanted metal roof with wood frame would work just fine. Keep it simple and spend your money on supplies, water supply, seeds and plenty of books on how to grow a garden :)


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