Hurricane & Tornado Proof Garage

[FrancisJ]

Needless to say, I'm on the Atlantic Coast and vulnerable to both hurricanes and the tornadoes they often spawn. Looking for inputs as to construction possibilities to deal with 150 + mph winds (should they occur).

Basic design is 24 x 72 and the pad, footings are already poured (16 yrds of concrete in the footings (18" x 18" x 192') and another 33 yrds went in the avg 6" deep pad). We used 4000 psi concrete with rebar throughout and protruded #6 3/4" rebar 48" out of the footings to tie into ICF. The walls will be constructed of ICF, horizontally and vertically reinforced with rebar, and I believe that will handle most loads (engineer says good up to 235-250 mph winds). Windows and doors will be impact-resistant and separately shuttered with 200 mph storm panels.

Questions:

(1) Recommendations on roof and infrastructure? (roof/ceiling rafters, trusses, decking, final mat'l)
(2) Recommendations for 9' high garage doors? (These won't be impact-resistant shuttered like the doors and windows and will need to deal with the forces on their own)

 

[jstroede]

ICC-500 maybe be a good document to reference. It covers design of storm shelters and various requirements. FEMA also has some publications on the subject, and Miami Dade County has a lot of information and code requirements, including product approvals.

http://ecodes.biz/ecodes_support/fr..._500-2008_StormShelters/ICC500-2008_main.html

That is the link to the ICC500 document.

http://www.miamidade.gov/building/pc-search_app.asp

There is a link to view Miami Dade County Florida product approvals.

This is going to be one crazy expensive build, but should last through most anything not involving a nuclear weapon.

John

 

[Falcon67]

Being from Texas and seeing what I've seen over the years, I'm going to say that anything above ground is not going to ever be "tornado proof". As above, maybe built like NORAD was going to use it.

 

[kbs2244]

Have you ever seen a "Tornado Alley" storm celler?
Under ground with dirt sloped out at a 30 to 20 degree angle.
That is the only way to not have a vertical wall for the wind to slam into.

 

[mburrus]

have it built to dade county (florida) codes. poured reenforced walls will be plenty strong (if icf means the hollow styrafoam forms im thinking of). for the roof, use hollow core concrete slabs or concrete twin tee beams. buildings built in this way survived a direct hit from andrew. i think the reason you see so much devistation with tornados in the midwest is that everything is built with stick or metal... a solid concrete structure should be extremely strong.

 

[DC73]

Questions:

(1) Recommendations on roof and infrastructure? (roof/ceiling rafters, trusses, decking, final mat'l)
(2) Recommendations for 9' high garage doors? (These won't be impact-resistant shuttered like the doors and windows and will need to deal with the forces on their own)

A few years back I was considering building an ICF home and did quite a bit of research. Can't remember the brand name but there is a company that makes styrofoam roof panels similar to ICF blocks for the purpose of pouring a concrete roof.

Another option that was presented to me was to use metal beams for the roof structure. The beams would be bolted via j-bolts embedded in the concrete walls. 3/4" plywood would get bolted to the metal beams and then a clay tile roof installed over that.

About the best you can do for the garage doors is to get hurricane rated doors. For additional support to keep the doors from blowing in you could rig up some type of bracket to support temporary wood beams that would go in place when a storm is coming.

DC

 

[rlitman]

What we really need to know is what state (and possibly what county) the OP is in.
That Dade County code for example gives you predictable protection from certain assumed maximum wind loads.

As for the comments about a real tornado shelter, what needs to be understood is that there are tordadoes, and there are tordadoes. Tornadoes that spin off of a hurricane are generally limited by the wind speed of the eye wall, so in a coastal area, adequate hurricane protection is what you want, not true severe tornado protection. So while Florida actually gets more tornadoes than Oklahoma, the wind speeds in each location are vastly different, which necessitate vastly different measures of protection.

 

[bczygan]

http://www.businessinsider.com/10-design-architectures-tornado-proof-home-2013-8

 

[aar0s]

Being from Texas and seeing what I've seen over the years, I'm going to say that anything above ground is not going to ever be "tornado proof". As above, maybe built like NORAD was going to use it.

This. Tornados don't so much blow houses over as the low pressure pulls them apart.

 

[racer1]

A few years ago, we had a large tornado go thru. Went straight down a residential development. wiped out all the houses, Except a house built with ICF's. blew a couple windows out, but very little damage. So....all other houses wiped out, What do you think every single one of the wiped out people built. OF COURSE.....stick houses!!!...so the wolf can blow them all down again....sheeeees.....Big eye roll........

 

[matt_i]

Cross-reinforced ICF is going to be pretty strong. I built my foundation walls with #4 bar on 16" centers vertical and horizontal, just to be thorough.

Rather than try to make the garage door as strong as possible, I'd try to back it up wiith a number of removable cross-braces. (i.e. install when the storm is coming) Its only going to be as strong as its skin and core, but you can backup the structure of the track and the rollers. If you are worried about penetration, I'd think 16ga epoxy coated steel would be a cheaper alternative to stainless. Keeping the wind out of the building as in a failed door scenario will limit the amount of uplift area to just the eaves rather than the entire area itself. Along those lines I'd want either steel plate or 3/4" plywood protectors which would be secured to the windows when a known storm is coming, to protect any glass. Backup the striker plates for deadbolt and normal door lock in the door frame with steel.

I think I'd go with standard-style trusses, you can come up with a system of steel clips to tie them down to anchor bolts set in the top of your walls. I'd backup code compliant nailing patterns with torx drive deck screws, something like #9 x 3", as those don't pull out of solid wood the way nails can.

Siding might be the stickiest detail. Attaching to the ICF itself isn't super strong. I suppose you could tapcon thru it to the concrete but again not super strong.

 

[BruceMc]

This. Tornados don't so much blow houses over as the low pressure pulls them apart.

And the flying debris -

http://www.colorado.edu/hazards/publications/wp/wp94/wp94.html#windborne

 

[Slowgsr]

For the roof,

I'd go with an ICF roof to match the walls

 

[matt_i]

ICF roof would be interesting and strong, but the foam can't be the outer surface as it will eventually degrade in the sun. Attaching more traditional materials like metal is certainly possible but its tough to get a strong connection short of anchor bolts cured or epoxied into the concrete.

Also, I'd think a ton of wood posts and plywood would be used in supporting the forms set on a diagonal/incline and filled thru the cupola, so they didn't collapse during the pour.

 

[Falcon67]

i think the reason you see so much devistation with tornados in the midwest is that everything is built with stick or metal... a solid concrete structure should be extremely strong.

F5 is a different animal. Not often, but as the people in OKC about frequency. Our hurricane preparedness when we lived in Houston was throwing a few things in the car and heading out 290 to see family 400 miles NW of the city. The storm can have the house.

https://en.wikipedia.org/wiki/1997_Central_Texas_tornado_outbreak

"The tornado produced some of the most extreme ground scouring ever documented, as the earth at and around the Double Creek estates was scoured out to a depth of 18 in (46 cm), reducing lush fields of grass to wide expanses of mud. When the tornado crossed county roads outside of Jarrell, it tore 500-foot (152 m) lengths of asphalt from the roads.[2] About 40 structures were completely destroyed by the tornado and dozens of vehicles were rendered unrecognizable after being thrown great distances, some more than half a mile. Some of the vehicles were pulverized into many pieces and strewn across fields, and others were simply never found. The vehicles that remained relatively intact were sandblasted and completely caked with mud and grass.[24] A small-steel frame recycling facility was completely obliterated, with nothing left of the structure but the foundation and a few mangled steel beams. Telephone poles in the area were snapped off at the base and splintered, and trees in the area were completely shredded and debarked.[24] Many researchers, after reviewing aerial damage photographs of Double Creek Estates, considered the Jarrell storm to be the most violent tornado, in terms of damage intensity, that they had ever seen.[25] Many of the homes in the tornado's path were well-constructed and bolted to their foundations, but the tornado left only the slab foundations, and there was virtually no debris left throughout most of the area.[26] The debris from the destroyed homes was finely granulated into small fragments, and scattered for long distances across the countryside. Several entire families were killed in the tornado, including all five members of the Igo family and all four members of the Moehring family.[27] The tornado's slow forward movement combined with it's extreme intensity were likely the main factors as to why the damage it produced was so remarkably intense. The tornado also picked up large amounts of loose soil as it deeply scoured the ground, producing a sandblasting effect on the houses and their occupants. Only one person was seriously injured and less than a dozen people suffered minor injuries after the tornado, a testament to the small probability of survival in the Double Creek neighborhood.[28]"

 

[GTO]

Tornado proof,that's some funny **** there...I don't think you will find that in any building code.If your're in the path of a tornado,it's over Johnny.

 

[FrancisJ]

Many thanks for the thoughtful and insightful comments from forum members -- I sincerely appreciate.

The garage is on the North Carolina coast (a "target" on the NOAA Historical Hurricane Tracker website) and we're struggling with the design for the roof and garage door --- both are weak spots. We've been using this FEMA guide

http://www.fema.gov/media-library/assets/documents/3293?id=1671

and it's been most helpful..

Our challenge is not so much the actual wind but the "missiles" the wind produces (e.g. 2x4s travelling at 100s mph). The ideas of a full concrete roof (i.e. "bunker") are interesting --- we'll have to work out the dead load numbers to see if the planned walls will support.

The garage door is another design issue (our goal is F3 tornado protection)--- Floridians often use additive horizontal and vertical bracing along with commercial tracks and thicker garage door panels, but that only gets you to F2. Haven't yet resolved the art of the possible to get to F3 and beyond.

The garage is needed to shelter a disabled family member along with my wife's animal rescue "herd" (rabbits, dogs, etc) --- neither are able to travel and it's hard getting motels/hotels if an evacuation is required.

Again, many thanks for your help.

 

[FrancisJ]

Being from Texas and seeing what I've seen over the years, I'm going to say that anything above ground is not going to ever be "tornado proof". As above, maybe built like NORAD was going to use it.

Having lived in San Antonio, Bastrop, Greenville, Wichita Falls and also Midwest City, OK (latter two being virtually flattened by tornadoes), I completely agree with your comment --- it's a tough problem building above ground to deal with these monsters like that "mile-wide" tornado that ripped thru Wichita Falls.

 

[theoldwizard1]

Go to the Simpson Strong Tie web site and download their catalog. The have dozens of different strap/connections to hold building together from high wind.

You will need additional hold downs beyond just bolting the bottom plate to the foundation. Vinyl siding will get blown off so consider something else (stucco, Hardi-Board?) In flood prone areas the walls are "sacrificial"; they are meant to be blown off.

If you have windows, get hurricane shutters. Make sure the garage door is rated for high wind and that you have a way of entering the garage when there is no power.

 

[jstroede]

So do you have actual test requirements you are looking for in these products? How many psf of design pressure are you looking for? What type of missile impact tests do you want it to pass? There are tests and standards for most of these things.

For the door, a rolling steel door is most likely going to be your best bet. They can meet some crazy design pressures and impact requirements.

John

Sent from my XT1254 using Tapatalk

 

[mburrus]

once again, i think either solid concrete all the way around and on top, or a precast concrete roof system is going to be impervious to nearly anything that the NC coast will see. we arent talking f5 tornado, but we are talking some potential cat 5 hurricanes... forget about metal or wood... concrete or concrete products. the roof on my shop is going to be wood truss, but in miami we have to use double hurricane straps made by nuvue, and they are cast in to the concrete tie beam. i am sheathing in 3/4 ply (code requires 5/8) and i will be supplementing with screws in the sheathing. the damage we saw in andrew was mostly lost roofs and poorly built stick houses coming down. we now have one of the nations most stringent structural codes as a result.

 

[wssix99]

Do you have enough wall space that you can have extra barn doors slide over your existing garage doors like extra storm shutters? (That might also look pretty nice, depending on how you design it.)

For the roof, one option you have is embedding steel plates at the top of the walls. This would allow you to weld steel trusses to the tops of your walls and go with a welded roof system to give you something really strong and resistant to uplift. (You could also go pitched or flat with the steel option.)

I'm in year three of a build on my ICF house and we have a number of steel beams that we had to embed steel welding plates in the walls for. (Putting them in the top of the wall would be a lot easier than the middle!). It's a common detail for engineers used to designing steel integrated with ICF.

We thought of doing a concrete roof and floors, but the construction time for these things is a killer and was a deal breaker for us.

 

[chops101]

Many thanks for the thoughtful and insightful comments from forum members -- I sincerely appreciate.

The garage is on the North Carolina coast (a "target" on the NOAA Historical Hurricane Tracker website) and we're struggling with the design for the roof and garage door --- both are weak spots. We've been using this FEMA guide

http://www.fema.gov/media-library/assets/documents/3293?id=1671

and it's been most helpful..

Our challenge is not so much the actual wind but the "missiles" the wind produces (e.g. 2x4s travelling at 100s mph). The ideas of a full concrete roof (i.e. "bunker") are interesting --- we'll have to work out the dead load numbers to see if the planned walls will support.

The garage door is another design issue (our goal is F3 tornado protection)--- Floridians often use additive horizontal and vertical bracing along with commercial tracks and thicker garage door panels, but that only gets you to F2. Haven't yet resolved the art of the possible to get to F3 and beyond.

The garage is needed to shelter a disabled family member along with my wife's animal rescue "herd" (rabbits, dogs, etc) --- neither are able to travel and it's hard getting motels/hotels if an evacuation is required.

Again, many thanks for your help.

Check with Clopay.
Doors around here are Cat 5 by code. Pricy, heavy, but survive-able.
There are only a few manufacturers that spec this as it is a small niche market.
And a 'second' to checking out Dade County codes, spec'd to their CBS construction techniques and your garage will stand a good chance of surviving Cat 5 storms.

 

[dreamingmuscle]

http://garagejournal.com/forum/showthread.php?t=1534

Check out the thread above. He builds one heck of a hurricane prof garage

Glen

 

[mikegt4]

I remember years ago watching a show about "extreme homes" when they showcased a home built on the Mississippi coast some where around Gulfport. The house was a reinforced concrete building somewhat like a dome home. The owner lamented about all of the trouble he had getting building permits because the house wasn't going to fit in with the existing (quaint) traditional buildings and the locals were not happy. About 9 months after Hurricane Katrina I happen to be driving along the coast on my way to Florida when I saw the house. It was the only building standing on that stretch of beach, apparently undamaged. I think that the homeowner got the last laugh.