Tornado Shelters and Safe Rooms

Bob Borson —  February 5, 2013 — 31 Comments

A tornado is a narrow, violently rotating column of air that extends from the base of a thunderstorm to the ground. Because wind is invisible, it is hard to see a tornado unless it forms a condensation funnel made up of water droplets, dust and debris. Tornadoes are the most violent of all atmospheric storms.

You might be surprised to learn that more tornadoes hit the United States than any other country in the world. Following up on that, Texas has more tornadoes than any other state. Following up on that, I live in Texas and we have a tornado shelter in the Cottonwood modern project I have been working on.

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Tornado Room with steel plate walls

We didn’t originally design this tornado shelter into the project but after an area not to far from the location of this house was hit by several tornadoes last summer, I received a phone call from the client requesting that we add one to the project. Since the foundation for the house was already poured, the wood floor joists in place, and walls were getting framed into place, my response to his request was “how serious are you about making this a “real” tornado shelter?” Unless you buy pre-made units – like the DuPont™ StormRoom™ with Kevlar® you have to follow certain construction rules – which in our case would have meant ripping out part of the foundation so we could isolate the portion where the tornado room would be built.

The owner elected not to go that far but other than the foundation, he wanted a viable tornado room … let’s call it a “safe” room. It’s a pretty good idea considering that some rooms have a fair amount of floor to ceiling glass walls.

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Tornado Room with steel plate walls 02

I took these pictures when I was on site in late December – most of what you see in these images has long since been covered up and won’t be as interesting to look at moving forward. This is a modern house but it isn’t so modern that the clients wanted raw plates of steel left exposed. It looks pretty good so I’ll have to remember this for the next “living the dream” loft project I take on. What we have here is a single layer of 14 gauge steel plate sheathing – “minimally attached.”

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Tornado Room with steel plate walls 03

Tornado Room with steel plate ceiling 01

The room isn’t particularly large – it measures 8′ x 5′ – which is the right size for a closet and for a temporary safe room … just not the right size if you wanted to play the Milton Bradley game of “Twister

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Tornado Room with steel plate ceiling 02

This is the guts of the safe room – double plates with tie downs, elevated floor, lowered ceiling that is not tied to the ceiling framing above … everything that FEMA recommends. Speaking of FEMA, I have include a few of the pages below (click to enlarge) that FEMA developed for the construction of this tornado/safe room. Rather than exhaustively detailing these spaces out in our drawings, we provided the contractor with the appropriate pages and referenced the details.

I am hoping that most – if not all – of the time that the clients will use this room will just be under the “threat” of a tornado rather than an “actual” tornado. As such, we are working to make sure that there is cellular connectivity in this room (a small challenge since the room is shrouded in 14 gauge plate steel) but other than that, this room doesn’t present any challenges to build out. There will be air distributed to the room so it won’t get hot and there is plenty of light (easier to see your playing cards that way). There was conversation at one point about installing a bar in this room but I think the client was kidding … sad to say, but the bar didn’t make the final cut.

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FEMA Safe Room Plan and wall Sections

FEMA Safe Room Section and Framing Details

FEMA Safe Room Door Details

Other than not complying with the foundation requirements, the walls and ceilings for this room are rated to withstand a EF-5 tornado (which is the biggest one there is). If you didn’t know, tornadoes are rated on the Enhanced Fujita scale (EF Scale), which rates tornadoes on their intensity based primarily on the damage tornadoes inflict upon man made structures and vegetation. There are 6 levels of tornadoes in the EF Scale system of classification:

EF0 = 65 to 85 mph with a damage path width between 10 to 50 meters (light damage) 38.9% of tornadoes meet this classification

EF1 = 86 to 109 mph with a damage path width between 30 to 150 meters (moderate damage) 35.6% of tornadoes meet this classification

EF2= 110 to 137 mph with a damage path width between 110 to 250 meters (significant damage) 19.4% of tornadoes meet this classification

EF3= 138 to 167 mph with a damage path width between 200 to 500 meters (severe damage) 4.9% of tornadoes meet this classification

EF4= 168 to 199 mph with a damage path width between 400 to 900 meters (devastating damage) 1.1% of tornadoes meet this classification

EF5 = 200 to 234 mph with a damage path width between 1,100 meters and up (incredible damage). Less than 0.1% of tornadoes meet this classification

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Some interesting facts about Tornadoes:

  • Most Tornadoes occur between 3pm and 9 pm
  • Tornadoes can happen anywhere in the world but most are in the United States – an estimated 1,200+ per year (approx 75% or the World’s total)
  • The state of Texas gets hit the hardest with an average of 125 tornadoes every year. Oklahoma (57) is second, followed by Florida (55) in third
  • Between 60 and 80 people a year die from tornadoes
  • The longest path of destruction created by a single tornado was 219 miles. That same tornado was on the ground for approximately 3.5 hours, moved at a ground pace of 73 miles per hour, and was the deadliest tornado on record in the United States – killing 695 people. (The Tri-State Tornado of March 18, 1925)
  • The World’s deadliest tornado occurred on April 26, 1989 in The People’s Republic of Bangladesh where a massive tornado took at least 1,300 lives.
  • Matt Suter of Fordland, Missouri holds the record for the longest known distance traveled by anyone picked up by a tornado who lived to tell about it. On March 12, 2006 he was carried 1307 feet (398 m), according to National Weather Service measurements.

 

For more facts about tornadoes, I’d recommend reading through NOAA National Severe Storms Laboratory FAQ page

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Good Luck!

Bob signature

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  • Hah

    Bob,
    We are building a tornado safe room into our home and are having a difficult one finding a door. I am wanting the safe room to look like the rest of our house (it will be a closet) do you have any suggestions? I am finding very little and what I am able to find is just a solid metal door… Any suggestions would be appreciate. Thanks.

    • http://www.lifeofanarchitect.com Bob Borson

      What we ended up doing was installing two doors – one that was a steel door that met the requirements of the storm shelter (which opened into the shelter) and one that was a door that looked like all the others in the house that opened away from the shelter.

      • Hah

        Thank you! Any suggestion for a company to order the door from?

        • http://www.lifeofanarchitect.com Bob Borson

          not really – it’s specific to where you live and in our case, I specify the characteristics of the door and the contractor takes on the responsibility of ordering it. Look at the last FEMA drawing I attached and use that to make some calls to door providers in your area.

  • Bee Safe Security

    Benefit of installing storm shelters on your property is the funding that is available to help supplement the cost. It is important to have a safe haven nearby that you can get to quickly.

  • Kate Tenitiss

    Bob,
    I just want to say thanks so much for such an informative and relavant article. As a resident of tornado alley who has spotted tornados in the Texas Panhandle and sat in bathtubs with my children late at night, I am deeply impressed. As a case manager for FEMA who helps tornado victims and their families with assistance for repairs, funerals and temporary housing, I have to say thank you again because the more people who read your article and protect themselves, the fewer who will need the more serious disaster services our country offers.
    Good Job!

    • http://www.lifeofanarchitect.com Bob Borson

      Thank you – I will take that high praise and feel good about myself for awhile!

  • Pingback: My take; Tornados, Storm Shelters & the Codes | The HTRC: Homeowner's & Trades Resource Center()

  • David

    When I worked for Vantem Panels in Texas I landed a contract to make the DuPont Kevlar SIP panels. I also took the standard SIP panels and had them coated with a polyurea (Rhino Lining) on both sides (they can apply any color) and then had the Texas Tech Tornado Lab shoot their 2×4 cannon at them. The 10″ panel passed FEMA criteria. The 4″ panel passed 140 mph for hurricanes.
    Some of the videos are on my Google+ page, but I no longer work for Vantem.

  • archaalto

    I’ll never forget watching an F4 [from afar] creep across the horizon we were pulled over on a KS interstate. A truly bone chilling and blood curdling sight…
    I think it’s one reason I left that part of the country.
    I know this is a bit of a side track, but that hot rolled steel plate looks sweet! I have used something similar for exterior cladding on a restaurant, with a clear powder coated finish to keep it dark. I’m curious now to see what it looks like incorporated with the completed finishes.

  • http://twitter.com/bensmithson ben smithson

    I need a tornado room mod done for a closet in my little MCM home. What kind of cha-ching price range are we talking about here? Dare I ask??!

    • http://www.lifeofanarchitect.com Bob Borson

      it sort of depends to what level of protection you are looking to provide. Lining the walls with 14 gauge steel plate, then plywood, than your interior finishes isn’t terribly expensive (particularly if you can do the work yourself. Materials costs are less than $2k. Tying everything down to the foundation is where the real costs come in. Basically you are looking to create a room within a room (dettached from surrounding structure) so that if your roof gets ripped off, the ceiling in your safe room will remain.

      To determine labor, you would have to be a lot more specific about your layout. If you use the FEMA sheets I have above, just about any competent contractor could let you know what sort of costs your looking at.

      • http://twitter.com/bensmithson ben smithson

        Thanks, Bob.

  • http://www.facebook.com/mike.mcconnaghy Mike McConnaghy

    I was probably way to happy to see that someone else has retrofitted a design to accommodate a ‘safe’ room into their plans. I have a question about the door type though: from the door way picture it looks as if there is a gap in the framing is that for a pocket style? Thanks for the post!

    • http://www.lifeofanarchitect.com Bob Borson

      I love how readers are really looking at what I putting up here – it keeps me honest.

      What you are seeing is, in fact, a recess for a pocket door. We actually have two doors that will get set in this wall – the outer pocket door will match the aesthetics of the house while an inner swinging door will be a steel door with three point locks on it.

      Boom! (no pun intended)

  • David Bourbon

    My mother was in the 1925 Tri-state (Missouri, Illinois, Indiana) tornado at her elementary school in DeSoto, IL. She never stopped talking about it.

    • http://www.lifeofanarchitect.com Bob Borson

      I can’t blame her – WOW!

  • http://www.facebook.com/profile.php?id=1189740256 Meg Alexander

    I’m glad that you made a post on having a storm shelter. I am amazed at how many homes and business do not have a shelter even though they live in tornado alley. Like everyone said, I don’t agree with how the shelter was put in but I do see that how you incorporated it into the structure was probably the best. I really think that all residential and business buildings within tornado alley should have shelters and that it should be required by code. I’m saying this because after see the damage of the Greensburg and Joplin tornados and all the other smaller tornados growing up I know the importance of the shelters.

    • http://www.lifeofanarchitect.com Bob Borson

      Thanks Meg!

  • Conrad Brown

    I suppose FEMA feels good about sheet metal and self tapping screws, but growing up in Oklahoma, and seeing houses peeled off their slab foundations leaving only floor tile to show where the bath and kitchens were, leaves me with doubt about anything not underground, if you really plan on surviving…take it underground.

    • http://www.lifeofanarchitect.com Bob Borson

      everything is about measures of degrees – you are probably correct in that the safest measure is to build a shelter (bunker) underground.
      Or if you really, really want to survive, live somewhere where they don’t get tornadoes.

      • name

        This room, as anchored would not survive an EF-5 tornado. A tornado of that intensity would rip this room completely off the floor joists.

        • http://www.lifeofanarchitect.com Bob Borson

          Yes … I know, even spoke about that in the post. Statistically less than 1/10th of 1 percent of ALL tornadoes is classified as an EF-5. Had we started with this program requirement, the foundation would have been isolated, but as a retrofit everything BUT the floor was structurally isolated. We’ll have to settle for an EF4 rating – I suppose we will just have to take some level of comfort in knowing that we are covered for 99.9% of all possible tornadoes.

  • Paul Anderson

    Not to be too picky here ( OK maybe just a bit ), but in a really serious tornado, isn’t the foundation connection pretty darned critical? I see it’s over wood floor framing. Is this on an upper floor? Are there also 2 layers of plywood and 14 GA steel sheet below? Am I asking too many questions? It’s simply because I’m interested.

    I certainly see this space as being great shelter from flying debris, bad guys etc. but in a “grand-poobah” tornado event (notably a different scale than the Enhanced Fujita) , a solid connection to Terra Firma would really be desirable.

    My picky comments notwithstanding, thanks again Bob for another interesting and informative post.

    • http://blog.SLS-Construction.com/ SLS Construction

      I can’t answer all the questions but as for foundation… Yes & No – For a direct hit for say a 3 or above it definitely would be, but probably not for the reason you are thinking – the biggest reason for the direct connection & support to the ground is when the debri piles up & collapses the framing

      For a 5 – well I rather be in an underground bunker as I know of certain forklift that was found 1/2 mile from where it was parked sitting upside down in someones basement

      Great piece & pics Bob

      • Paul Anderson

        I hadn’t considered debris “drifts” but it makes sense just like sand and snow. Thanks for that.

    • http://www.lifeofanarchitect.com Bob Borson

      Hi Paul – you are exactly right about the importance of the foundation but not because it needs to sit on the ground but rather for being isolated from the rest of the structure. This room is one the first floor but is not on “terra firma” and it doesn’t need to be on the ground to meet FEMA guidelines – it just needs its own foundation.

      In later photos (which weren’t as interesting and are currently on my phone) 2 layers of plywood were added to the exterior walls and to the steel ceiling. Also missing in these photos (again, added later) were double sole plates and double staggered blocking.

  • TALV58

    You know, I’ve always wondered why there wasn’t a mandatory code to build storm shelters in all new construction that was in the potential areas of tornadoes. I know I’d want something.

    • http://www.lifeofanarchitect.com Bob Borson

      You are probably right even though, most tornadoes don’t happened in congested metropolitan areas. Maybe the local counties should do something about the requirement – at least the builders and architects who work in those areas should provide a space like this – they are easy and not very expensive to build. Could save the lives of your family.

  • Drew Hasson

    I love it when non-government employees (I was in the Army) discover and actually utilize FEMA services. After all, we pay plenty of taxes to Uncle Sugar. I have been telling people for years and years about realities and preparations like this. Very nicely done Bob. Looks like the contractor’s doing it right with putting this room together. Spoken like a true Texan by the way… “In Texas we this… In Texas we that…” the best part is, looks like you’ve got some problems solved.

    • http://www.lifeofanarchitect.com Bob Borson

      Thanks Drew – sometimes just knowing something exists is the difference between using it or not. It took me a long time to track this information down but now that I have it, I use it all the time.

      Cheers