fema above ground storm shelter
baldheadcarpenter
| Posted in Construction Techniques on
We are building an above ground storm safe room for a client. I was wondering if anyone knows how fema comes up with there specs. this is a wood framed room with 2 layers of 3/4 plywood and one layer of sheetmetal 1/16 thick. the design doesn’t seem very strong compared to concrete or block room. everything is tied together with metal connectors but it still seems very weak. I think myboss downloaded the plans from the fema website. Iwas wondering if any of y’all had built one.
Replies
Never built one, but I have seen a simple 1x2 hunk of trim go into a block wall, just shooting out of a radial arm saw.
Imagine a 2x4 in a tornado..it'd go right thru if it missed a web. The 1/16 sheet metal seems like a good choice as a speed killer, if it's nailed on the edges , it's like catching a baby in a blanket dropped from a window, it'll stretch like a membrane ( hopefully).
Spheramid Enterprises Architectural Woodworks
Repairs, Remodeling, Restorations
I would guess the FEMA design was influenced by research done at Texas Tech. Might do a search and see what you can find.
Never built one myself
i think that design was a "better than nothing" that can be built in existing homes by diyer
http://www.google.com/search?q=fema+%2B+safe+room&ie=utf-8&oe=utf-8&aq=t&rls=org.mozilla:en-US:official&client=firefox-a
http://www.fema.gov/plan/prevent/saferoom/
all you could want and more
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baldheaded carpenter.
Please don't underestimate the strength of wood, especially plywood. World war 2 showed that airplanes made of plywood could fly fight and survive as well as metal planes could (actaully better)
Nor should you over estimate the strength of block walls. They are really weak.
Poured concrete walls though with sufficent rebar to give it strength and vibrated well to keep it deviod of air pockets should be able to provide a great deal of strength.
ICF walls have up to a 4 hour fire rating and are capable of withstanding 200 MPH winds..
we just finish a ICF condo in Long Beach Ms, that rated for 300 mph winds
but will an ICF prevent a 2x4 traveling at 200mph from penetrating?
bobl Volo, non valeo
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"But when you're a kibbutzer and have no responsibility to decide the facts and apply the law, you can reach any conclusion you want because it doesn't matter." SHG
bobl.
I don't see why not. How many 2x4's have you seen penitrating bridge pillars etc.
All an ICF is is a form to pour concrete into. that concrete has steel rebar in it to give it added strength so it's not like concrete block which can be smashed with a simple blow of a sledge hammer. It's solid reinforced concrete up to 15 inches thick.
I had to shake my head and rub my eyes to see if I read that right, then I realized it was just frenchy making stuff up again, right?Who makes an ICF that gives you 15" thick concrete?
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Piffin,
Oops sorry it's 15 inches total thickness in a Rewards form but if you veneer a wall with 4 inch stone as I did you'll wind up back at that thickness.
However if you watch the test where they shot 2x4's into just 6 inch thick walls and they didn't penetrate I think that 11 inches is more than adequite don't you?
Of course Reward does make a brick ledge wall that will give you your 15 inches of concrete
I don't doubt that the typical 6" of re-inforced crete in an ICF will do the job.It was the claim that it was normally 15" that gave me whiplash in the double-take
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Piffin.
I'm sorry I looked at the chart and it listed 15 inches.. so I wrote it down. mea copa (you have to really read the data sheet to find where it says the fill is only 10 inches)..
I do know that 15 inches is fairly common size but I can't tell you off the top of my head which manufactures have them and which don't .
The typical is 11.5" ext of foam block with about five inches of the being the foam. 6.5" of crete is allBut of course thickness is not all there is to it. 3" thick perfectly blown and cured ferrocrete would do the job.I've been reading at the fema site booklets oday because am designing a house with a safe room. IMO, the fema stuff is pretty basic and avoids direct specifications as though they are trying to avoid liability. BUt I'm sure there is some govt entity with the good stuff.
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Piffin
My foundation wall called for 13 inch forms with 8 inches of concrete. Just looking at various stacks of forms I would say that's the most common called for here in Minnesota..
NUDURA has a 12" core unit -- 17 1/4" overall width.
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That'd make a safe room for the apocalypse!
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My neighbor built a safe room in the middlke of his house. Basically standard Florida block wall, #5 dowelled cells tied into the footer, on the regular schedule, tie beam but he also tied corner bars in the top, put down decking, a grid of #5 and poured all cells along with a concrete roof.
This is a vestibule coming into his house like a mud room, with 2 steel doors, one going out, one into the house. Once he got the drywall up it just looks like a regular room but it is tough.
I think it ought to be code everywhere for a safe room.
brownbagg,
It's not bad enough that our homes can become virtual prisons now you want every home to have a jail cell?
Frenchy,
As a parent with two small kids the idea of a jail cell in the middle of my house is very attractive. If anybody had a tantrum, I could send them to the brig!
But to the OP and others, the design of the FEMA safe room for a single family home is based on the assumption that the room will be located somewhere in the interior of the house. The concerns that frenchy has posted in this topic, and in a few others, are spot on: wood is strong and block is strong but neither can take serious projectile damage well enough to protect a family from flying debris. So the FEMA design assumes that your room is bolted to the foundation separately, has separate walls that are not attached to load bearing structures in the rest of the house, and is located in the center of the house so that the combination of the plywood and metal sheeting in the walls will be able to take most projectiles that make it through the exterior house structure. There are quite a few cases where the FEMA design has held up very well and the safe room is the only part of the house left standing after a tornado.
From an aesthetic point of view, I like the plans that show the safe room as a room behind a fire place that could also be used for storage. The home owners can put a fake stone veneer on the on the whole fireplace and safe room exterior so that it looks like one big unit and then the rooms are arrayed in an open four square kind of set-up around the fire place and safe room. But something like this is much more easily handled at the design and initial construction phase than during a remodel. For a remodel, IMO, I'd want an architect, an engineer and a good contractor to go over the plans and figure out how to do it right.
Chris
My neighbor made the conscious decision that one door of two, would open directly outside so they wouldn't be trapped if the house fell down around the room.
"I think it ought to be code everywhere for a safe room."
Everywhere? Why would I want a safe room and what would it be keeping me safe from?
Falling firs?The next Nipponese tsunami?
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I thought safe rooms were for people with something worth stealing. Yeah I'll definately take one that would keep the firs off when the wind gets up.
Nah, a saafe room is to keep you safe from whatever your local nightmare is.
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Now I'm really confused. You are saying a safe room protects you from unskilled , overpriced subs?
A customer of mine manufactures these;
http://www.twistersafe.com/
web site is a little cheesy, but they tested at Texas Tech. They are good for fitting in a garage if you've got a little room. I think 5 x 4 feet is their smallest for around $4,500.
Tracy
LOL
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Why would I want a safe room and what would it be keeping me safe from? from somebody breaking in or to keep all your valuable or guns in
We are using a 3 point locking steel door and jamb. Block walls poured solid with concrete and reinforced with concrete would be better.I am tired of drillingholes in sheetmetal for screws,3inches oncenter at the seams 6inches in the field. This room is a add in off of a kitchen remodel. there are more straps and metal connectors in this wooden structure tieing every thing together than in any thing else I have built. when I was in 5th grade a tornado hit the small town I lived in. my Mom and I stood outside watching it spin in the sky until i got to scared and talked her into going into the basement at school. luckily no one was hurt.
In Florida you are already dropping a #5 in about 20% of the block cells and pouring them solid along with a solid tie beam on the top 16" of the wall so pouring all of the cells solid is not much farther to go.
I've been curious about the doors. Are those regular steel entry swing doors or an upgrade? which direction they should swing is also part of my wonderings. Three point locking would be superior to regular old striker and deadbolt.On the fema site I was reading, they do not recommend wood frame construction, but simila to what you describe, while leaving other options on the table as possible. They did point out that structurally the room should be entirely independent, so that if a tornado lifts or destroys the rest of the building, it does not leverage the safe room apart or take it along with the main.
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These are just heavy duty steel entry doors but I think he does have supplimentry dead bolts top and bottom. I didn't really look that closely since any door in Florida has to be 130MPH rated if you are in this zone. Most are 150. My garage door is.
but will an ICF prevent a 2x4 traveling at 200mph from penetrating?
Yes. http://www.youtube.com/watch?v=ocEmJ_D-uP4You get out of life what you put into it......minus taxes.
Marv
I know you have probably built your shelter already but there are some companies that make them to fit in a garge.
http://www.tornadoandstormshelters.com/flatsafe.html
Sometimes. engineers actually do serve a useful purpose. Designing a shelter might be such an instance.
Simply taking someone's "rated" design isn't enough ... you have to understand just what the rating means, how the tests are conducted, and - probably most important - identify exactly what hazards you wish to endure.
For example, a basement might be great in a tornado - and lousy in a flood. Brick might do well against a hurricane, but poorly in an earthquake.
Just what is a "safe room?" Didn't Jodie Foster have one in one of her movies?
To get the right answers, you need to ask the right questions.
Go to the FEMA website and look for the download of FEMA 361. That is the Community Shelter Manual from several years ago. There is an appendix in that manual which lists 20+ wall sections(concrete, block, ICF, Wood studs with concrete infill and many more). These may all come from the Texas Tech studies. But that appendix gives info on how well repeated 100 mph wood 2x4's (stud length) penetrate the various wall sections. As somebody else said make sure you review the details for tying the walls to the foundation and tying walls and ceilings together. Not much protection if the walls and roof come apart.
You might be interested in reviewing the Parsons MFG building collapse in an F4 tornado. The workers in the the shelters there could hear the cars bouncing off the walls as the the cars in the parking lots were tossed around by the tornado.
Jim Hannah
"FEMA 361. That is the Community Shelter Manual"Thanks - that explains why I was not seeing anything specific - I was in their residential section. Who'dathink that I need to go to community based to get individual information? LOL
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hello everyone!
A concrete safe room, built with concrete blocks and a poured concrete roof, is the way to go. I didn’t feel like any wooden structure would be safe enough. The combination of stress changes and increased wind speeds can cause normal building components to fail. In new construction, one or more regular basement walls can be reinforced to use as shelter walls if they do not contain windows or other openings. The shelter must have a special ceiling that resists penetration from debris above.
nice insights regarding the matter, works well in clientele explanation for similar concerns and great concept for future endeavor of the project and information resource option. please do provide some photos of the frame for reference i would really appreciate it. have a great day ahead.
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Evacuation is still the best way to avoid the full impact of these mega storms.
Matt Pierce
http://anteglobal.blog.ca
http://www.smartsafeshelters.com
You're spamming a 3-year-old thread.
EF4 damage
ThisThis was our home. The wood is a 1"x4"x12' piece of wood. It stabbed completely through the chimney. I don't trust above ground shelters because our foundation was lifted and cracked. Our neighbors home was completely wiped off the foundation with nothing left but a slab. We were underground.