Tag Archives: Tornado shelter design

Should I be designing my storm shelter per the ICC-500 or the FEMA P-361?

Recently we have had a couple clients ask about community storm shelter peer reviews and why we are peer reviewing the designs per the ICC-500 and not the FEMA P-361?  The simplest answer is the ICC-500 is a standard that is tied directly to the building code and the FEMA P-361 is a guideline.  The ICC-500 must be followed if you are designing a storm shelter using the IBC 2009 or later.  The FEMA P-361 guidelines may also be required if the storm shelter is funded by a FEMA grant.

The next question we are often asked is if there are discrepancies between the two documents? That question can be answered by the FEMA P-361 Appendix D which is a “Comparison Matrix of Differences between ICC 500 Requirements and FEMA Recommended Criteria.”  As you can see by the provided matrix the main differences are in regards to coastal flooding shelters and first aid kits.

Thanks for following, and remember.  Ask questions, do your research, and make an informed decision. The lives of you or others may depend on it.

Written by Shauna Schultz, AIA

“If you are not underground you will not survive!”

As storm shelter designers we constantly hear the statement made that “You cannot survive an EF4 or EF5 tornado unless you are underground”. This information couldn’t be further from the truth. We now know there are codes in place to assist designers and engineers in designing above ground shelters that will withstand an EF5 tornado and provide near-absolute protection to those seeking refuge during the storm.

There have been several above ground shelters in the past few years which have performed quite well in tornados in Oklahoma. To my knowledge there has only been one fatality in an above ground shelter that was constructed per the FEMA P-320 EXCEPT it was found to have had a non-tested door assembly installed. (Reference Schultz Squared Architects’ earlier blog for this information.)

While there is nothing wrong with the idea of being underground in the event of the tornado, I would like to point out some of the potential, problems with underground shelters.

  1.  Bobber Effect: This one is pretty scary, and with the large amounts of rain and the ground becoming saturated last summer in Oklahoma there were numerous tornado shelters that actually floated out of the ground just like a fishing bobber in water!Tornado Shelter Failurtes-Bobbers
  2. Water infiltration: Whenever a portion of any building is put underground, there is always a potential for ground water to find its way into the building either through surface water or ground water. For obvious reasons the last thing that you need is a tornado shelter that has doubled as an underground swimming pool! Many of the residential underground shelters do not provide waterproofing and/or drainage system around the exterior (similar to a foundation drain around your basement that dumps into your sump) and over time, this could become an issue for you.Tornado Shelter Failure-water infiltration
  3. Exiting: If you are underground in a debris carrying tornado and it drops your house/building on the door, does anyone know to look for you as you may become trapped for some time before being “dug” out. If that’s the case let’s just hope the torrential rains do not follow the tornado or…see issue number 2.
  4.  Accessibility: In a residential shelter stairs are an acceptable method of accessing an underground tornado shelter, for the elderly or physically impaired person whether temporarily or permanently this may not be feasible. In a community shelter wheelchair, accessibility route must be provided along with (2) exits from an underground space, which adds significant cost to the design of the facility.
  5.  Ventilation: The building code requires a certain amount of ventilation be provided for both residential and community shelters. Some of that ventilation should be near the floor and some near the roof of the shelter. This is much more difficult to accomplish in a community underground shelter. Another issue regarding ventilation/infiltration are hazardous vapors, anything that is heavier than air will have a tendency to find its way into your underground shelter, i.e. solvents, paint, gasoline, diesel, & kerosene, all of which could be disastrous if it finds its way to a flame source either internal or external to the shelter.

If you decide an underground shelter is right for your building/house do your research and make sure the designer/supplier is reputable and knows how to prevent the issues I have listed above because the tornado is not the only danger that may surround the event. Please don’t misinterpret this blog and believe I am telling you to avoid a well-designed/installed underground shelter as it may be the best place for you to be in a high wind event. Just understand what you are getting yourself into.

Thanks for following, and remember. Ask questions, do your research, and make an informed decision. The lives of you or others may depend on it. Written by Shauna Schultz, AIA

Tornado Shelters-ICC-500 2014 Commentary is Available

It’s been a while since our last blog….”We’ve been busy!”

I just received my OFFICIAL copy of the ICC 500-2014 Standard and COMMENTARY!  We were one of several volunteers that help write the commentary.  It can be purchased from the International Code Council at www.iccsafe.org for about $42.00.  You can get either soft bound or a PDF copy.  There is a discount for ICC members.

Even after being involved, I am a little disappointed in some aspects of the commentary.  The volunteer committee had the opportunity to review and comment on an early draft copy of the commentary.  Unfortunately, at least in my case, many of my comments were not addressed.  In the end, the volunteer committee was not given an opportunity to review the final draft of the document and subsequently, in my humble opinion, there are mistakes.  I believe once it is read through, those issues will be glaring to a designer.  Bear in mind that a large portion of the commentary was written by those that do not design or produce shelters and therefore do not understand the real world ramifications of the commentary, the code standard, and/or the building code.

I will point out one of the least problematic mistakes….in the credits, they have our firm name as “Schultz Architects, LLC”.  I guess someone could not figure out what “Squared” meant.  With all the free time and effort that this company has put forth for this document, you would think….Needless to say, not happy!!!!  That is just the proverbial tip of the iceberg!

If someone can explain figure 304.9 to me, I would GREATLY appreciate it!  Also, watch out for 309.1 comments!

It’s unfortunate but now that it is published, “it is what it is”!

Be careful out there!

Written by Corey Schultz, AIA, LEED BD+C

 

Using Toilets for Tornado Shelter Space

Sanitation facilities are required for community tornado shelters.  After conducting several peer reviews over the past few months, I am seeing this trend in using required toilets as shelter space.  To clarify, these restrooms have been single fixture restrooms intended to be utilized by one person at a time.  That is ONE, not 10 or 11!  Some designers are including these required restrooms in the shelter’s overall occupant load count.

Let’s consider an example.  I have a 450 sf (gross) training room with (2) single fixture restrooms, each about 85 sf (gross) both of which are required by code to support the shelter occupants. The following would be the proper calculation for the occupant load:

  • Training Room – 450 x 65% Reduction Factor ÷ 5 sf/occupant = 58
  • Restrooms – 2 rooms x 0 occupants = 0
  • Total Occupant Load of the Shelter = 58

Here, the restrooms are designed for the use of occupants that are in the training room.  This is the most conservative approach.  One could include ONE occupant in each restroom on top of the 58 in the training thus a total of 60 occupants.  The thought is a one for one trade from the training room to restrooms as individuals need to use the restroom.

Now here is a calculation that I see as a trend:

  • Training Room – 450 x 65% Reduction Factor ÷ 5 sf/occupant = 58
  • Restrooms – 2 x 85 x 65% Reduction Factor ÷ 5 sf/occupant rooms = 22
  • Total Occupant Load of the Shelter = 80

First of all, the reduction factor should be 50% for a restroom so it is a problem right from the get go.  The fixtures and door swing take up a lot of the restroom space.  So what happens when two people have to use the restroom?  Two occupants go in, 22 come out.  A net of 20 additional occupants now in the Training Room.  THE TRAINING ROOM IS NOW TOO SMALL!!!!  It just doesn’t work!   If you need 80 occupants, then size the Training Room for a minimum of 78 or 80.  If you have additional restrooms that are over and above the minimum, then one could consider loading it up with occupants; people that don’t mind standing in restroom with 7-8 (based on the example with a 50% reduction factor) what could be perfect strangers for 2 hours or more.  That wouldn’t be for me!

I think this trend is to justify more occupants than necessary to justify more space that is funded by a government agency.  In other words getting space paid for by that government agency that will never be used as shelter space.  Here’s the sad part; those funds provided by government agencies are fixed and those “pots of gold” as some refer to it do run out.  So therefore, when a building owner with the help of a designer takes more grant money than what they need, then another group, maybe kids in a school may not get a shelter because the funds have dried up.  In the end, it could cost that particular designer another shelter project to boot!

It’s that simple!

 

Be careful out there!

Written by Corey Schultz, AIA, LEED BD+C

Tornado Shelter Door Monitoring

In a previous blog we discussed the concept of keeping tornado shelter doors locked so the exterior hardware that could be hit by debris thus activating the latch and potentially allowing the door to be opened by the wind. The locking of these doors should be included in the shelter management plan.

But what about securing the doors from the inside?  As humans, we all deal with stress in many different ways.  Experiencing a direct hit by a tornado can be a highly stressful situation.  Some people get mad, others crawl into a corner in a fetal position, and others feel they need to get away, the flight reaction.  These are the people that can be a big problem for other shelter occupants.  In many shelters, doors can be locked from the outside but those with panic devices remain unlocked from the interior.  If someone has the flight reaction at the wrong time, they could head toward one of these doors at the exact wrong time and potentially put everyone in the shelter at risk

As humans, we are also very curious and when the preverbal “stuff” is hitting the fan, we have a tendency to want to watch, the old rubber necking when going by a vehicle accident.  There is no place for opening shelter doors and/or protective devices in a shelter to see what is going on outside.  These protective devices MUST stay closed especially when the storm is near. This is vital to the safety of everyone seeking refuge inside the designed safe room.

As a part of the management plan, people that deal with stress very well should be assigned a position at each exterior door to make sure that someone does not open the door(s) whether on purpose or by accident.

 

Be careful out there!

Written by Corey Schultz, AIA, LEED BD+C

Locking Tornado Shelter Doors

As a part of any tornado shelter management plan should be a requirement to lock all shelter doors before the storm hits.  Let’s exam why is this important.

Some believe locking the shelter door is to keep out people that were not intended to be supported by a shelter.  I guess that could be true in some circumstances.  Others believe that locking the doors is intended to keep the door from being opened at the wrong time.  This is true.  One does not want to open any shelter door if it is susceptible to strong winds that could damage the door and keep it from operating when the storm strikes.

The other BIG reason to lock these doors that many designer’s and building owners miss is to keep debris from activating the exterior door hardware and unlatching the door which could cause it to open.  Sounds pretty simple, right?  What happens in public use shelters where the doors may be automatically unlocked by some sort of technology (which I believe is a disaster waiting to happen and will be discussed in a different blog), who locks those doors?  The public that you are automatically letting into the shelter don’t have a key or if they did, they wouldn’t need it to automatically open.

Make sure all shelter doors are locked!!!

Be careful out there!

Written by Corey Schultz, AIA, LEED BD+C

Now where was I……Oh yeah!  Recently, I sat on the steering committee for the third edition of the FEMA P-361 document which I am happy to inform you that it is now available for download free of charge at www.fema.gov.  I just received an e-mail from the Project Manager for the revisions of the FEMA P-361 that states there were some problems with the initial upload of the documents so if you happened to download a copy prior to 4/28/15, I would recommend downloading it again.

Also available is the latest edition of the ICC 500, the 2014 edition which I was a voting member of the ICC Committee.  It can be purchased from the International Code Council at www.iccsafe.org for about $32.00.  There is a discount for ICC members.

fema_p361_search_previewThe FEMA P-361 has gone through a major overhaul especially with the format.  The document has been revised to align with the format of the ICC 500.  For designers, it is soooo much easier to cross reference with the ICC 500, which saves time.  The content of the FEMA P-361 has been revised to be more in line with the requirements of the ICC 500-2014.  Another improvement is a matrix which shows the remaining differences between the FEMA P-361 and the ICC 500.

There have been several changes in the ICC 500 too numerous to discuss here.  I think the most positive item is commentary for the document (yeahhhhhh) which is long overdue.  There is a committee of which I have volunteered that is currently working on the commentary document which should be out later this fall.

Be careful out there!

Written By Corey Schultz, AIA, LEED AP BD+C

Tornado Shelters – THANK YOU FEMA!

A few weeks ago I wrote about a tornado safe room/shelter door failure that cost an elderly lady in Arkansas her life.  This was truly a tragedy.  A tragedy that could’ve been avoided through education.  FEMA took the initiative to produce an educational document for homeowners regarding tornado safe room/shelter doors.  I think it is a really great document that is pretty simple to understand.  If you are considering building a shelter or even buying one that is pre-manufactured, this is a must read.  I have no doubt if the elderly lady in Arkansas had been aware of this information, she would still be alive today.

This document can be downloaded from the FEMA website at
http://www.fema.gov/media-library/assets/documents/99139

For your convenience, I have also embedded the actual document here.

Safe Room Door Fact Sheet Page 001 Safe Room Door Fact Sheet Page 002

 

Read it, think about it, and heed the information.  It may save your life or the life of a loved one someday.

Be careful out there!

Written By Corey Schultz, AIA, LEED AP BD+C

Tornado Shelters-The “3 ½” Concrete Slab Issue

The 3 ½” concrete slab issue is one that I have attempted to distance myself from because I spoke against it in the initial ICC-500 code committee and got resoundingly shot down by the rest of the group.  Please allow me to explain the issue as I originally saw it and now that I know more, how it stands now.

Section 309.1.2.1 of the 2008 edition of the ICC-500 states”

Slabs on grade shall be designed for applicable loads in accordance with Section 301.  Where a slab on grade is being used to resist loads, the minimum thickness shall be 3 ½ inches (88.9 mm) and the minimum steel reinforcement for slabs on grade resisting forces on the storm shelter shall be 6×6-W1.4 by W1.4 or No. 4 bars, 18 inches on center in either direction.

I was opposed to this language for one reason and one reason only.  I knew when people (i.e. designers, engineers, manufacturers) read this, they believe that a 3 ½” slab will work for any type of shelter as long as it has the reinforcing indicated without the need to have it engineered.  Low and behold, we have small residential shelters made of steel, wood, and other composite materials that are light weight being bolted to existing concrete slabs without doing any design work to confirm that the 3 ½” slab will work as required by the first sentence of the paragraph noted above!  I knew it would happen!!  I knew it!

I know of four competent, practicing structural engineers that have looked at this very issue and not a one of them could engineer a 3 ½” slab to work with these light weight shelters that experience the full wind load; NOT ONE!!!  Why?  BECAUSE IT DOESN’T WORK!!!  The wind forces attempt to overturn these light weight shelters but doesn’t have enough “lead in its ass” to resist it so it depends on the dead weight of the concrete slab to resist the force.  Problem is, the 3 ½” concrete slab doesn’t have enough “lead in ITS ass” to resist the force either!

With that said, there are exception to every rule.  If you have one of the heavier shelters, i.e. fully reinforced masonry, and/or concrete, there may be enough dead weight in the walls and roof of the shelter to resist the overturning force.  There are stipulations to this in the ICC-500, and only engineering will determine this.  Shelters that are located in basements and do not see the full wind load may also be an exception, but again, this needs to be verified!

The latest version of the ICC-500 which has yet to be released has reworded this paragraph to hopefully emphasize the need for engineering these slabs.  The problem is going to be, will pre-fab shelter manufacturers pick up on this and comply?  Do you think Home Depot which sells shelters on the internet is going to make sure that you have an engineered slab on which to install your newly purchased shelter?  I hardly doubt it!

So when you see manufactured shelters that say they can be bolted to an existing slab without any type of engineered verification, STAY AWAY!  It is a must that there is enough dead load to keep the shelter from overturning, where ever that dead load comes from.  It could be footings/foundations, thick floor slab (like 2’ thick), heavy walls, and/or roof structure.  But bolting to an existing slab that is 3 ½” thick, or 4” thick is not going to cut it!  You probably did not purchase a tornado shelter, you purchased a bad carnival ride!  And one that could kill or serious injure you and your family.

Be careful out there!

Post by Corey Schultz, AIA, LEED BD+C

Tornado Shelters – Peer Reviews

Being an architect, I can say that for some reason it is in our nature, the architectural community, never to turn work down unless, we feel that it is WAY over our heads to provide services on a particular project UNLESS we are willing to find a consultant that can help us through…..on everything except tornado shelters.  I just don’t get it!  It appears that a majority, not all, but a majority feel that shelters are nothing more than adding a little more rebar in the walls, putting those shutter “thingies” over the windows, installing vault doors, and putting concrete or dirt on the roof.  “I’m done!  Problem solved!”  Unfortunately, it is well beyond those issues, WELL BEYOND!

And because of these reasons, the ICC-500 and the FEMA 361 call for peer reviews as a shelter/safe room requirement for both architectural (coming in the next editions) and structural (current requirement) for any shelter that protects more than 50 occupants.  It is a second set of eyes to help assure that the end users of that shelter are safe in a tornadic event.  THAT’S IT!!!

So, if I were a designer that had never done a shelter but just could not turn down the project due to lack of experience, it would be a REALLY good idea for that designer to get their shelter peer reviewed by someone that has some shelter experience.  BETTER YET, put them on the design team so that intelligent decisions can be made through out the process!  OMG, what a novel idea?  OR if I were an experienced shelter/safe room designer, wouldn’t the second set of eyes be a good idea anyway?  You need to avoid the temptation of hiring your buddy at another firm that knows nothing about shelter design, to review your shelters and you’ll review his.  The “scratch mine/scratch yours” scenario.  That’s a lose/lose situation!  You may save a little money but your neck just become as long as a giraffe’s!  AND a big target for a law suit should something go wrong!

I have had the opportunity to conduct peer reviews for six other architects in the past couple of years, which has amounted to 14 different tornado shelter/safe room.  And out of all 14 projects, not a single one of them were without several issues.  These are what I would consider really good architectural firms and half of them were experienced shelter designers!  And that is only on the architectural side of things.  Not sure where they stood on the structural reviews.

Peer reviews are important.  Peer reviews are something that should not be left until the end of the construction document phase.  Why?  How many architects out there have enough working budget to redo the project if the shelter was completely botched?  Not many that I know.  So then what happens?  Poor decision making?  YES!  Justifying design mistakes?  YES!  And who knows what else!  Peer reviews should start at the schematic design level and continue throughout the design process.

So check your egos at the door and find someone to watch over your shoulder.  Someone’s life and/or your livelihood as an architect/engineer could depend on it!!!

Be careful out there!

Post by Corey Schultz, AIA, LEED AP BD+C