A tornado-proof house

[Thomas Loades]

According to Snowden Flora's Tornadoes of the United States, there were a number of "tornado-proof" houses built in Kansas City, MO, by Colonel W. H. Nelson, “founder of the Kansas City Star and a man noted for the thoroughness of his methods.†These houses were, in 1953, located along Harrison Street between forty-seventh and Brush Creek Boulevard; and, to make them tornado-proof, they were built with —

•Two-by-sixes, rather than two-by-fours, for studding
•Twice as many nails as were ordinarily used in houses of the time (which seems to be around 1913)
•studdings bolted to the joists, which were bolted to iron plate beds which were secured to the foundation by ¾-inch bolts 8 inches long to anchor the houses to their foundations
•Two "huge" chimneys to anchor the houses and act as a vent for the air pressure drop (which in those days was, of course, explosive!)
•all eaves made short and securely boxed in, "with the idea of preventing wind from getting under the roofs."

In the first place, would this kind of arrangement work to save a house from severe damage in a tornado? (Have we any structural engineers in the crowd?)

Also, if this method wouldn't work, is there any method that could be used to secure an entire house against the effets of a tornado? Or is a safe room the most we can go by?

And does anyone know if these houses are still there? (Or if they had ever endured any tornadoes?)

 

[Larry J. Kosch]

Severe Damage to Houses

I would think the extra structural beefing would help the houses to sustain winds and damage in tornadoes in the F0-F2 range. But this will only delay the inevitable as stronger tornadoes or winds will damage the house or at least strip away the upper floors and or roofs. Eventually a F-4 or a F-5 will just simply blow the houses away, chimney vents and all.

I would think a safe room, built with today's materials and technologies, would be a better alternative than to be living in a house built in the early 1900's. Back then the housing industry were not as savy about building the houses to withstand a F-5 tornado.

If there were two houses built side by side, one from about 1915 and one from this year, and say a F-3 tornado hits them broadside, which one would you think will survive the damage the best?

I would think a safe room would be a better alternative. I've seen Internet ads where you can put a fiberglass molded safe room in your backyard for a hefty price. And plans are available to build concrete models in homes too. 8)

 

[Carrie Halliday]

I am not sure any structure can be tornado proof (especially in an F 5) but the new concrete constructed homes look to be the best bet. I would rather go with a concrete saferoom than a basement. Too many fatalities down in them due to the home collapsing and being a low spot to catch debris. :shock:

 

[Glen Romine]

Well, I'm not a structural engineer, but I've heard several talks on this type of stuff, such as at the Fujita scale symposium a few years back. As I recall, the primary mode of home failure starts with the garage door collapsing inward, as these are rarely engineered to withstand the pressures of tornadic winds given their large surface areas (particularly two car garage doors). Therefore, step one is to have a detached garage or reinforce the door rails by attaching to 4x4 posts bolted to the foundation and using a higher gauge rail. Once the garage door fails, this pressurizes the interior of the home, usually blowing out sheathing off of the roof next. But, if the forcing is sustained, large sections of rroof can be removed, as generally home building relies on gravity to hold things down, aside from a few nails. So, using hurricane clips is recommended to help secure the roof timbers to the frame of the home.

After the roof is lifted, the side walls are less secure, and, particularly if the home is not bolted to the foundation, exterior walls on the side facing the strongest wind will generally fail next. As such, you should always insist that the home is bolted to the foundation. A brick home will not necessarily fair better, particularly if clips were not properly used to bond the brick fascade to the frame of the home. Once exterior walls start to fail, interior walls are exposed, which generally have much less structural integrity and so with continued onslaught of strong winds these can fail as well.

Of course, your home's construction is only as good as your neighbor's home upwind. A safe room is probably a good option, I think some survived the recent F-4 in Moore. A basement is vulnerable to debris falling in on you, which is why some advise going to the SW corner of the basement, which increases the odds that you aren't in the corner of the basement where most of your home's debris ends up.

Glen

 

[rdale]

"A basement is vulnerable to debris falling in on you, which is why some advise going to the SW corner of the basement, which increases the odds that you aren't in the corner of the basement where most of your home's debris ends up. "

I thought that advice came because of the "tornadoes approach from the southwest" of old days? Isn't it better to be under the stairway in a basement regardless of where? Or does debris really end up in that corner?

 

[David Wolfson]

I was one of a group who was caught eating supper at a Cracker Barrel north of OKC on May 9th last year as a tornado moved just to our south. In taking shelter in the restaurant's walk-in freezer, it became apparent that there were no significant requirements in the commercial codes or standards regarding storm shelters. The building code requirements are apparently limited to gust loading and represent a "minimum", according to Tim Marshall: http://www.stormtrack.org/library/damage/moore.htm
This article also has some good tips about what works for tornado survival.

 

[Shane Adams]

Originally posted by rdale
\"A basement is vulnerable to debris falling in on you, which is why some advise going to the SW corner of the basement, which increases the odds that you aren't in the corner of the basement where most of your home's debris ends up. \"

I thought that advice came because of the \"tornadoes approach from the southwest\" of old days? Isn't it better to be under the stairway in a basement regardless of where? Or does debris really end up in that corner?

The Mulvane tornado was survived by the mother and youngest son by takinjg shelter under the basement stairs; debris was piled on top of their entrance area, and the debris had to be removed to get them out, but they escaped with no injuries. Pretty great testament to the integrity of that stair well considering two entire walls inside the basement were removed.

 

[Glen Romine]

Yes, the stairwell does offer more protection if you don't have a true ceiling or shelter in your basement. I didn't see it specifically mentioned in FEMA's shelter guide, but it makes sense that it would be better than not having anything structural over the top of you. The staircase act as a sort of leanto - but you are relying on it's structural integrity to protect you from the loading weight of the piled up debris on top. I'd note that the current FEMA guidlines do not suggest the staircase - but they recommend having a true shelter. Maybe a staircase is "plan B" for those who can't afford it.

For those interested, here is a link to an information booklet:

http://www.fema.gov/pdf/fima/fema320.pdf

 

[Richard Halter]

I would suspect that having a chimney on both ends of those homes would just add to the potential destruction, especially if they are made of brick.

To me, a concrete steel re-enforced room in a basement is the best way to go, as it gets you out of the line of fire of above-ground fying debris, and since the momentum of simple collapsing house isn't that strong, the structure should be able to hold up at the bottom of any pile.

 

[Scott Currens]

This type of home would survive an F4/F5.

http://www.monolithic.com/gallery/homes/be...each/index.html

On second thought, if a violent tornado hit a monolithic dome or any steel reinforced concrete structure it would likely be rated F0 or F1.

Scott Currens

 

[Steven Williams]

To me, a concrete steel re-enforced room in a basement is the best way to go

Yes, you can't go past steel reinforced concrete for strength, and its a basic, relatively inexpensive building material.