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Mother Nature and Air Supported Structures

Special post by Mike Toika

As the world becomes even more hectic with people trying to balance work, exercise and family time, we are leaving less to chance with Mother Nature.  People don’t have time for inclement weather to interfere with their schedules.  Fortunately, technology has come to save the day with its new “golf domes” or, more accurately, air supported structures.   So now we can perform our activities, rain or shine!

Air supported structures are becoming more commonplace.  They are being used as golf domes, multipurpose facilities, field houses for athletic events, and more.  Building code enforcement becomes a little tricky when dealing with these structures.  The building codes that we commonly enforce, from I.C.C., B.O.C.A, or even NFPA 101 Life Safety address very little about these types of structures.  And why should they?  After all, most codes are developed following a major incident.  For example, the Iroquois Theater Fire helped change. the code for exit door swing.  As we remember, hundreds of people died in that fire, many of them against the theater doors, that swung into the venue, not outwards.  Most air supported structures have never had any kind of catastrophic failure involving major injury or loss of life.  So, why should we be concerned??

The evolution of the “air supported” structure is advancing quickly.  These structures are becoming larger and can be limitless in potential uses.   We are seeing high schools use them for field houses.  Local Park Districts are using them as multipurpose facilities, for everything from golf to soccer fields and even haunted houses.  With the use of these structures changing, so is the potential occupant load.  Air supported structures are evolving  from a golf practice dome, where a small amount of adult individuals go to hit a few golf balls, to a major sports venue with teams of children and their cheering families.  This, is the reason why we need to be concerned.

The International Building Code, B.O.C.A. Building Code, and National Fire Protection Association break these air supported structures into two categories, Temporary Structures, and Permanent Structures. Temporary Structures are defined as “those structures erected for a period of less than 180 days”.  Temporary structures shall comply with the International Fire Code, as per the International Building Code.  Permanent structures are governed by the International Building Code. This becomes important because manufacturers of these type structures recommend that the structure “not” be deflated and inflated religiously.  This makes these structures permanent in nature.  So, if the facility is going to be up, why shouldn’t it be used?

All the standard building and fire code issues need to be addressed, including fire protection, means of egress, occupant loads, etc.  But what are the issues?

What are the differences?

Where are the differences between the International Building Code, and the International Fire Code?

Where does NFPA fall into play?

Lets try to elaborate

First it comes down to the definition…how long is the structure to be up?  As stated earlier, manufacturer’s recommendations are not to take the structures down when not in use.  This would require a variance by the local authority having jurisdiction to consider the structure temporary.

Next is occupant load.  If occupant loads stay under 50 persons then no special requirements are noted from the International Building Code.  However, should the occupant load exceed 50 then all kinds of requirements are put into motion, none of which as important as the “support provisions”.  Chapter 31 of the International Building Code states that “a system capable of supporting the structure in the event of deflation shall be provided for in air-supported and air-inflated structures having an occupant load of 50 or more….”.

What does this detail??  What type of support structure??  Why, if over a swimming pool, as stated in NFPA 101, and IBC Chapter 31, does it have to be present no matter what the occupant load?  It is safe to suffice that it has to do with the amount of time to exit a swimming pool, and then make it safely out of the structure should a failure occur.

Manufacturers will argue that auxiliary inflation systems meet this requirement.  However, auxiliary systems are “provided with sufficient capacity to maintain the inflation of the structure in case of primary system failure”, according to the International Building Code.  This does not address the issue of a catastrophic failure, and these auxiliary systems  are required on all air-supported or air-inflated structures.  So, if this is the requirement on all of these structures, why is there a requirement for support provisions?

I would like to argue that in the event of a catastrophic failure of the structure, that the support provision delays the collapsing of the membrane, allowing the increased occupant load to quickly and safely exit the structure.  This can be proven by the recent collapse of the Dallas Cowboy’s Air Supported Practice Facility.  There was no secondary support system in place and the catastrophic collapse was extremely rapid.  Light standards that some manufactures will argue meet that requirement did nothing to slow that collapse down, but in fact aided in paralyzing one coach.

So why shouldn’t we be concerned about these structures.  They are no longer being used for the golf dome.  They are being used as a cost effective, large area cover for all types of multi-purpose uses.

I believe that these structures are safe, as golf domes.  I am not convinced that there is enough knowledge, or data, pertaining to these facilities as multi-purpose facilities for us to believe that they are safe as multi-purpose facilities.  As history proves, the majority of building and fire safety codes are developed due to some catastrophic incident that has happened.

It is not to say that a major catastrophic event is imminent.  However the Dallas Cowboy Practice Facility collapse should start to raise some very large RED flags.  We should we be proactive, instead of reactive!  We have one documented failure.

Why shouldn’t we prepare ourselves to defend the installation of support structures?  Why shouldn’t we dictate what support structures are?  These are questions that need to be addressed.  We need to be proactive in our review of existing codes and the code development process.  We need to better define what secondary support systems are, close the loop holes of temporary versus permanent structures by not allowing the common variance based on time the structure is used.

Only then  can we be prepared for our first multi-purpose facility?

ABOUT THE AUTHOR

Lt. Mike Toika, member of the Addison Fire Protection District #1 for 30 years.  Currently a line officer on Black Shift.  On his non shift days, Lt. Toika functions as a Fire Inspector/Plan Reviewer for the Addison Fire Prevention Bureau.  He has been an inspector for 13 years, and has been performing plan reviews for 7 years.

ABOUT THE PHOTOGRAPHER Mark Spoo
Fire Photographer and Investigator for 20+ Years. Fire Inspector for the last year with the Addison Fire Protection District. Previously was fire inspector with the Village of Bensenville and part time inspector with the River Grove Fire Department.

{ 3 comments… add one }

  • Paul Sabaj July 6, 2009, 7:22 am

    Great article. I have seen more of these structures used for field houses and other sport related events. I see a problem where they want to take it from the intended use and occupancy such as golf range and after hours make it a soccer field or hold an indoor art fair. My second concern is how long is the structure cover good for and how can you test it? Thanks for the article.

  • Tim Rogers July 6, 2009, 2:41 pm

    Excellent article! It has always been that people (either in volume or of importance,) have to die before codes addressing these problems are created or, more importantly, accepted. The mentality of “It happens to someone else, not me,” prevails when it comes to safety vs. dollars. Granted, sometimes we have to have an event to realize there is an issue, but we have to keep trying.

  • Wayne Morris July 8, 2009, 12:35 pm

    Another issue to consider, I have seen one of these structures in a very rural area in Alabama, very far from fire protection in the form of substantial manpower and equipment, used for a church. There was obviously no code enforcement due to there is only 1 exit, and it looked to have a large occupant load.

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