Oklahoma City Adopts Resilience Code

By Scott Kriner, Green Metal Consulting

Autumn has arrived, the leaves are bursting into brilliant colors, and the nights are cool. It’s hard to believe that we are in the fourth quarter of 2014 already. It is often good to reflect on the events of the year. And the first three quarters of the year were packed full of events that disrupted the lives of many Americans. From wildfires in the Western states, to flash flooding in the Southwest, to a significant earthquake and aftershocks in California, hurricanes in the Atlantic and Pacific oceans, and wind and hail damage from thunderstorms just about everywhere in the summer.

This calls out the importance of our communities and public policy making changes to focus on resilience. Whether it is constructing more resilient buildings or making plans for more resilient neighborhoods and regions, 2014 already has been a year where concerns over resilience have come to the forefront.

There are now building programs and assessment tools for improving the resilience of new construction and existing buildings in both the residential and commercial building market. Just to name a few, the Institute for Business and Home Safety (IBHS) has their FORTIFIED HOME™, FORTIFIED for Safer Living®, and FORTIFIED for Safer Business™ programs. The National Science Foundation has a tool for assessing a disruptive and damaging event, and the Department of Homeland Security has their RESILIENCE STAR™ program to build and retrofit homes in hurricane prone areas.

A growing number of trade associations representing manufacturers of building materials are also developing their own guides for resilient construction. This includes the Engineered Wood Association, the Portland Cement Association and the American Iron and Steel Institute.

The first city that recently adopted a building code that calls for more resistance and resilience in a tornado prone area is Moore, OK. On average, 50 tornadoes hit OK each year between March and August. Over 95% of those are EF0, EF1 or EF2 in strength. The stronger storms and tornadoes are normally more deadly and devastating to the towns and communities in their path. The new standard in Moore calls for homes to withstand 135 mph winds. Storms rated at EF3, EF4 or EF5 would still damage buildings, but the building code provisions are at least better than what Moore had before. The resiliency from this new code is focused on the resistance of homes to weaker storms and also resiliency of homes in the peripheral areas of the stronger tornadoes.

Some of the examples of changes in the new Moore building code include requirement of sheathing on roofs, improved anchoring of the structure, better securement at edges, requirement of plywood or OSB on gable end walls, and requirement of insulated and storm-resistant garage doors.

The new provisions are based on information gathered from the NSF’s RAPID tool, ASCE-7 2010 loads and the 2009 IBC and IRC.

More cities are taking similar action to improve the ability of the built community to resist damage from high wind events and/or to bounce back from minimal damage and resume normal activity and services quicker.

A closer look at the IBHS FORTIFIED program reveals the strategy that many other resilient programs are using. The FORTIFIED program is broad based but very detailed and covers resistance to natural disaster events such as flooding, hail, wildfire, severe winter weather, hurricanes and earthquakes.

The resilience criteria for high wind events of any type cover the type of framing materials and their dimensions, the size and type of fasteners, bracing and anchoring to foundations. There are also height restrictions and the requirement of designing an adequate load path from the roof to the foundation. In the case of a roof system being blown off, a secondary water resistant underlayment is required. Even the type of acceptable roof system material is included in the program.

Likewise, for buildings in hail storm prone areas, ratings are required on all openings such as doors, windows, skylights. And a hail impact resistant roof system is required. To prevent or minimize damage from severe winter weather the program requires some of the high wind event protocols and also calls for special roof and attic design to avoid ice damming.

The enforcement of the FORTIFIED program comes in the way of review of the initial construction plans, followed by multiple site inspections during construction, by certified IBHS inspectors.

Estimates of the average added cost for these types of resiliency improvements have been reported to be around $1/ft2. When compared to the replacement cost of the building due to a significant storm, flood or other type of disruptive event, the incremental cost can often pale in comparison.

The good news for the metal construction industry is that steel and other metals are already included in some of the programs mentioned above. More work remains to be done to promote the features and benefits of metal construction components and assemblies in the field of resilient building design. Metal’s high strength –to-weight ratio, ductility, impact resistance and corrosion resistance make it a wise choice for resilient building design.

Scott Kriner is the president and founder of Green Metal Consulting Inc. He is a LEED Accredited Professional who began his career in the metal construction industry in 1981. His company is a member of the U.S. Green Building Council, the California Association of Building Energy Consultants and the Residential Energy Services Network (RESNET).

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