The concept of “hurricane proofing” is really a misnomer. How “proof” are we talking? How big a hurricane? etc. These questions have been recently partially answered at least by new laws and requirements in the International Building and the International Residential Codes. The truth is there is no such thing as “hurricane proof”; one can only meet and then choose to exceed the requirements.
Our track record:
Waring Architects was both pleased and relieved to discover that, in the aftermath of Hurricanes Katrina and Rita in 2005, not one of our new construction projects built throughout the history of the firm, was damaged. There were no structural failures, no broken windows, no windblown rain damage, no peeled back roofs, no flood damage. To a large degree, admittedly, this is a function of sheer luck. Having said that, this good fortune was also a function of careful planning, quality design, good structural engineering, and meticulous construction phase Contract Administration services. Most of the credit goes to outstanding structural engineering by the Professional Engineers who work with us on all of our projects.
Types of damage:
There are four basic types of hurricane damage:
1. Structural Damage,
2. General Wind Damage,
3. Windblown Rain Damage, and
4. Flooding Damage.
Engineering safety factors: Structural engineering involves the process of analytically calculating first, the weight of the construction (known as “dead loads”); second, the weight of the occupants and all of their possession (known as “live loads”); and, third, the forces imposed on the structure by wind and seismic forces (known as “lateral loads”). A Structural Engineer calculates these individual numbers as worst-case scenarios, that is to say, the most they could ever reasonably be…and then doubles them. This is the “100% safety factor” that represents the “industry standard of care” for professional structural engineering.Upon occasion, we will also request that our engineers deliberately calculate to exceed the 100% safety factor for parts of, or the entirety of, a particular structure.
Hurricane-force winds: By solving for these numbers, always rounding up, and designing the structure to be able to easily accommodate them, the Engineer, the Architect, and the Property Owner can all be reasonably confident that, if the building has been professionally engineered and constructed to withstand the lateral wind loading equivalent to hurricane force winds of 140 mph (the code requirement), that structurally-certified building should not experience catastrophic failure until winds reach forces in excess of 280 mph.
Construction integrity: Beyond all of this the structural engineer designs the building’s structural systems so that all aspects of the building are firmly tied together, from the tips of the pilings deep underground all the way up through the structure to the very top of the roof. WaringArchitects believes that several techniques and systems, above and beyond those required by the straightforward structural calculations, are occasionally appropriate, particularly for those projects that we feel are at greatest risk. For example, we believe that the tops of the pilings should be physically attached to the steel reinforced concrete slab using reinforcing steel Rebar driven into or through the piling. We also very much like spring-loaded vertical steel building ties that communicate all the way up through the structure and allow some structural flexing of the building under gusting extreme wind conditions.
Why engineering? Our structural engineers carry Professional Errors and Omissions Liability Insurance that covers the entire structure in perpetuity. In short, we very strongly believe that professional structural engineering is one of the best investments a property owner can ever make. We insist on professional structural engineering whenever and wherever it is required in every project that we undertake. No exceptions.
General wind damage:
Manufacturer specifications: As a general rule, we absolutely require that all materials installed in or on the building must be installed per the manufacturer’s recommendations. The manufacturer’s specifications are already designed to be able to withstand the statutory wind loading.
Extra reinforcing: Since Katrina, we have been requiring that our contractors double the fastening requirements for roofing materials, just to be on the safe side. Roofing manufacturers have already designed the fastening specifications so that the roof system will meet Code. It is our opinion that the cost of taking this extra step of supplementary fasteners is so insignificant that it is more than justified by the added safety and protection the building enjoys in the event of a major storm. We have also taken care to ensure that exposed elements of the building, like air-conditioning condenser units, are securely fastened down. Windblown “missile damage is another source of potentially severe wind damage, since this is usually how the building’s envelope is breached.
Windblown rain damage:
Envelope breaching: What we have learned from our experience with hurricanes here in New Orleans is that the vast majority of the damage suffered by a building in a hurricane is due to windblown rain as a result of doors, windows, and roofs being breached. The Building Codes now require that, in any part of the country that is designated at-risk for high velocity winds, windows must be constructed of rated and certified impact resistant glass mounted in a rated and certified frame as a rated and certified “assembly”.
Hurricane Windows: This does not necessarily mean that the window won’t break; it only means that, in the event that the window breaks, it will not breach and windblown rain will not be able to get into the structure. These rated window assemblies are very expensive and require complete replacement if they are damaged. The Codes offer, as an alternative, the option of protective covers that provide at least the equivalent of a 3/4 inch layer of plywood over the opening. These covers can be in the form of rolldown metal shutters or thick wood or aluminum batten-style shutters.
WISP: There is one other alternative which has been developed and of which we have only recently learned, the WISP Window. We are extremely enthusiastic about this product, have just used them on a major project; we have discussed these windows and provided a link to the manufacturer’s web site elsewhere on our site.
Flooding damage: By surge:V-Zones In coastal locations properties can be subject to “surge” flooding. This is a terrible situation in which a tsunami-like wall of water is accumulated in front of a hurricane and pushed ashore, causing not only flood damage but, also, tremendous physical impact-damage as a result of its inherently huge kinetic force. Many coastal zones have been designated as “V-Zones” (“V” for “Velocity”) by FEMA. Regulations require that any walls built below a stipulated elevation be designed to be “breakaway” construction. This essentially protects the structure by eliminating the resistance that might bring the building down in the event that a wall of water comes slamming into it.
Protection Proper structural design to manage this surge flooding risk will include:
1. Piers or columns that are more than capable of withstanding the forces;
2. Good construction oversight to ensure that breakaway walls are properly constructed;
3. A well constructed foundation that is properly tied to pilings and protected against being undermined by rushing floodwaters.
By rainwater accumulation:
Drainage and runoff: The other more common source of flooding comes from the tremendous amounts of rainfall that can be dumped in a short period of time by a hurricane or any other severe rain event. When this happens, existing available ground absorption and drainage run-off simply cannot handle such a large volume of water, particularly in flat or low-lying areas. The result of this, coupled with the storm surge and the levee breach, is what the nation observed in bowl-shaped New Orleans in the aftermath of hurricanes Katrina and Rita.
FEMA: The Federal Emergency Management Administration (FEMA) has strictly mandated that any and all new construction be designed and built to protect the home or business from the vast majority of flooding events. Their standard is the so-called “100-year” flood event, a flood of such severity that it is not considered likely to happen more frequently than once in every hundred years. They use this standard to develop, for each and every location, a specific flood zone designation.
BFE: For every flood zone designation there is a corresponding elevation to which the structure must be raised. This is called the Benchmark Flood Elevation (BFE). The height of a building relative to that established elevation is used by insurance underwriters to determine the corresponding cost to the property owner of the flood insurance for the property. All flood insurance risk in America is underwritten by the United States Federal Government through FEMA.
Construction Elevation: FEMA requires that any new construction be elevated to above the benchmark flood elevation or 3 feet above nearest adjacent existing grade, whichever is higher. They also require that any enclosed parts of the building below BFE cannot be covered by flood insurance, cannot be used for living purposes and must be provided with openings to prevent “hydrostatic pressure”. This is defined as the crushing forces that occur or when rising water surrounds an enclosed area. These openings allow water to flow into and out of that area to ensure that the structural bearing capacity of those walls is not compromised.
Waring Architects strongly recommends to our clients that whenever and wherever possible, they think of the BFE as only a starting point in terms of determining the planned elevation of the structure. There are significant flood insurance savings for every 6 inches above the BFE the building is actually constructed. Frankly, we use the terrible flooding of 2005 as our own recommended benchmark to our clients.
A Working Prototype: We have recently designed and built an extraordinary prototypical structure in Slidell, Louisiana that we believe represents a clear example of the paradigm shift in coastal design and construction. We invite you to closely evaluate and consider the 365 Carr Drive project which we have outlined in detail elsewhere on our site.
Disclaimer: Having said all of that, please remember that I’m sharing with you my best understanding concerning all of this. Every project is different; otherwise, why would you need an architect? Before you absolutely rely on anything here, it is really important that you let us take a look at your individual situation, your individual home, your individual property. I don’t want anyone to construe any of this as the absolute last word on anything. Stuff changes all the time. Needless to say, we’re not structural engineers; nor are we solar panel manufacturers; wind turbine generator manufacturers; accountants; or, for that matter, lawyers. That’s why I believe that consultation with licensed, insured, professionals is so important.
We are, and always have been, determined to continue to be a New Orleans-based architecture firm.
Our offices were flooded and so was my home. Our team was scattered to the four winds. Lives were lost. Irreplaceable drawings were lost. Data had to be painfully reconstructed. Our lives, our firm, and our careers all had to be painfully reconstructed.
We know what we’re talking about from first-hand experience when it comes to understanding the risks of coastal hurricane damage. We have a strong and vested interest in promoting good design to manage this risk reasonably and appropriately.
If you’re interested in investing wisely, protecting your possessions and building your home or business…just once; you should call us!