Which Tornado Saferoom is Right for You?

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Image courtesy of FLASH.

There certainly seems to be increased awareness of the potential for damage and injury from tornadoes these days. Recent information published by the Federal Emergency Management Agency (FEMA) and the Federal Alliance for Safe Homes (FLASH) help explain that. This increased awareness has led to a growing interest in tornado shelters for protection of life and property.

This FEMA graphic shows that most areas of the United States have been affected by a tornado at some point since 1996, and many have been affected by one or more strong tornadoes (EF3 or greater).

Figure 1 - Tornado activity by county: 1996-2013

Figure 1 – Tornado activity by county: 1996-2013

Living in North Texas near the Simpson Strong-Tie manufacturing plant in McKinney, Texas, I know all too well the sinking feeling of hearing the tornado sirens and turning on the TV to find you are under a tornado watch. FLASH recently published a graphic developed by the National Weather Service that shows the large number of U.S. counties that have been under a tornado watch between 2003-2014, and the high number of warnings that some counties experienced.

Figure 2 -  Annual average number of hours under NWS/SPC tornado watches (2003-2014)

Figure 2 – Annual average number of hours under NWS/SPC tornado watches (2003-2014)

Other than moving to an area that has fewer tornadoes, one of the best ways to protect your family and at least have more peace of mind during tornado season is to have a tornado shelter or safe room. These structures are designed and tested to resist the highest winds that meteorologists and engineers believe occur at ground level during a tornado and the debris that is contained in tornado winds.

Tornado shelters can be either pre-fabricated and installed by a specialty shelter manufacturer, or can be site-built from a designed plan or pre-engineered plan. A good source for information on pre-fabricated shelters is the National Storm Shelter Association, a self-policing organization that has strict requirements for the design, testing and installation of its members’ shelters.

FEMA publishes a document, P-320, Taking Shelter from the Storm, that provides good information on safe rooms in general, as well as several pre-engineered plans for tornado safe rooms.

To highlight the different types of safe rooms covered by FEMA P-320, FEMA, FLASH and the Portland Cement Association (PCA) sponsored an exhibit at January’s International Builder’s Show. The exhibit was called the “Home Safe Home Tornado Saferoom Showcase.” It featured six different types of saferooms that builders could incorporate into the homes they build. Simpson Strong-Tie and the American Wood Council collaborated to build a wood frame with steel sheathing safe room meeting the FEMA P-320 plans. Other safe rooms shown at the exhibit included pre-cast concrete and pre-manufactured steel shelters manufactured by NSSA members, and reinforced CMU, ICF cast-in-place concrete and aluminum formed cast-in-place concrete built to FEMA P-320 plans.

Figure 4 - Home Safe Home Tornado Saferoom Showcase

Figure 4 – Home Safe Home Tornado Saferoom Showcase

Simpson Strong-Tie staff in McKinney, Texas, constructed the wood frame/steel sheathing safe room in panels and shipped it to the show. It was built from locally sourced lumber, readily available fasteners and connectors and sheets of 16 ga. steel (which we happen to keep here at the factory). It had cut-away sheathing at the corners to show the three layers of sheathing needed. Our message to builders was that this type of shelter would be the easiest for their framers to build on their sites.

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Figure 5: Holdowns and plate anchorage

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Figure 6: Roof-to-wall connections

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Figure 7: A visitor examines our tested door, a vital component of any shelter. This one was furnished by CECO Doors.

The sponsors of the exhibit took advantage of the variety of safe rooms in one place to film a video series, “Which Tornado Safe Room is Right for You?The videos are posted at the FLASH StrongHomes channel on YouTube. The series provides comparative information on cast-in-place, concrete block masonry, insulated concrete forms, precast concrete and wood-frame safe rooms, with the goal of helping consumers to better understand their tornado safe room options.

“Today’s marketplace offers an unprecedented range of high-performing, affordable options to save lives and preserve peace of mind for the millions of families in the path of severe weather,” said FLASH President and CEO Leslie Chapman-Henderson. “These videos will help families understand their options for a properly built safe room that will deliver life safety when it counts.”

FLASH released the videos earlier this month as part America’s PrepareAthon!, a grassroots campaign to increase community emergency preparedness and resilience through hazard-specific drills, group discussions and exercises. The overall goal of the program is to get individuals to understand which disasters could happen in their community, know what to do to be safe and mitigate damage from those disasters, take action to increase their preparedness, and go one step farther by participating in resilience planning for their community. Currently, the program focuses on preparing for the disasters of tornadoes, hurricanes, floods, wildfires, earthquakes and winter storms.

Do you know what the risk of disasters is in your community? If you are subject to tornado risk, would you like to build your own safe room, have one built to pre-engineered plans or buy one from a reputable manufacturer? Let us know in the comments below.

Storm Shelters in the Wake of the Oklahoma Tornado

As we continue to learn more about the devastation in Oklahoma from the EF-5 tornado that struck the city of Moore and surrounding areas on Monday, many building professionals and homeowners are questioning the safety of their homes and other structures in tornado-prone areas. Winds of the recent storm reached speeds up to 210 miles per hour and destroyed hundreds of homes, businesses, schools and hospitals. Many structures were leveled to their foundations. The question that is posed after an event like this is – can you build a tornado-resistant home or structure?

A recent article in the Huffington Post asked that question to several design professionals, including our own resident code expert, Randy Shackelford, P.E., a Simpson Strong-Tie engineer based in McKinney, Texas. While designing a tornado-proof home is not practical or economical, properly designed storm shelters can save lives. Take a look at the Huffington Post article here.

Last year, I wrote a post about Building a Storm Shelter to ICC-500 Design Requirements, which presents the most economical solution to resisting the strongest of tornadoes. We’ve also covered this topic from various angles in the blog, from design – a post about Code-Plus Programs that provides some guidelines for building structures that are more resistant to hazards than what the code requires, Designing Light-Frame Wood Structures for Resisting Tornadoes and checking for Building Drift – to addressing specific parts of a structure, such as Preventing Roof Tiles from Becoming Wind-Borne Debris and Roof Deck Design Considerations for High Wind Events. Our Technical Bulletin about how to strengthen dwellings in tornado-prone areas provides further information.

Our thoughts and prayers continue to be with everyone affected by the Oklahoma tornado. We are thankful to report that our local sales reps and families in that area are safe. If you have additional thoughts about the tornado and storm protection, please leave me a comment.

– Paul

Top 3 Roof Deck Design Considerations for High Wind Events

Was it JFK who said, “The time to repair the roof is when the sun is shining?” He was likely using the roof as an analogy for the economy, but I take things literally and wanted to talk about roofs.  The time to think about the design of your roof and its function in a high wind event like a hurricane or tornado is right now.

Wood screw vs. common nail

During a high wind event, a roof deck is expected to perform many functions. It should prevent water intrusion from rain, withstand impacts and protect those inside from hail. It also needs to act as a diaphragm – transferring lateral loads to shear walls and resisting the vacuum effects of wind uplift forces. Continue reading

Building a Storm Shelter to ICC-500 Design Requirements

According to the National Weather Service, 2011 ranked right up there as one of the worst years on record for tornadoes, having set records for the earliest date of the first tornado, the most states reporting tornadoes, the greatest monthly total, the greatest daily total, and the highest estimated property and crop losses. (Take a look.)

You may wonder: What can I do to protect building occupants (perhaps even my family) in a tornado? It is possible to build your home to higher wind resistance than normally required so that it can resist weak to moderate tornadoes? See my previous blog post, “Designing Light-Frame Wood Structures for Resisting Tornadoes. It Can Be Done!” and also our tornado technical bulletin for more information. But to resist the strongest of tornadoes, the most economical solution is a storm shelter located nearby or in your home.    Continue reading

Breaking News: The Weather Channel Series on Huntsville Tornado Recovery

Next week, The Weather Channel (TWC) will be airing a series of programs on the Huntsville, AL tornado and recovery efforts. Each segment airs four times a day (actual times are CDT, listed below.) TWC interviewed Dr. Richard Stanley, a Georgia Tech researcher and a builder himself, about well-connected homes for the Huntsville series, but he didn’t have any homes at the construction stage to show the necessary hardware. Simpson Strong-Tie employees Sam Hensen, Russ Anderson, Jeremy Orton and Mark Richardson at our McKinney, TX branch provided Richard with a two-story mock-up detailing a continuous load path for his interview. The mock-up was used in a segment of the filming.

Continue reading