Choosing Resiliency: Lessons from Hurricane Michael

In this post, Doug Allen, P.E., a structural engineer with Simpson Strong-Tie, looks at the choice homeowners in disaster-prone areas face between simply building to code and building to standards of resilience or IBHS FORTIFIED Home™ standards instead.

Resilience, or resiliency: The capacity to recover quickly from difficulties; toughness. The ability of a substance or object to spring back into shape; elasticity.

In the wake of the most recent and very devastating hurricane seasons, the theme of structural resiliency has resurfaced with renewed urgency for increasing numbers of homeowners, builders, Designers and civic planners. Hurricanes pose a triple threat of high winds, substantial rain and storm surge. Extreme weather has cost the nation nearly $100 billion in damage during 2018. Accordingly, awareness has risen within affected and surrounding coastal regions regarding their communities’ existing structural resilience ratings (low or high) and the need to improve in view of the losses as well as the time and cost to rebuild what was destroyed.
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Habitat for Humanity Introduces Habitat Strong Program

You’re probably already familiar with Habitat for Humanity, a nonprofit builder of simple, decent and affordable homes for low-income families around the world. According to builderonline.com, they were the 15th-largest builder in the country in 2015 when ranked by number of closings. Simpson Strong-Tie has been an official national partner with Habitat for Humanity since 2007, making contributions of cash and products exceeding $2.5 million in that time, and Simpson Strong-Tie employees have spent hundreds of hours building homes and training local Habitat affiliates.

Habitat for Humanity Home

We know from working on Habitat houses that they tend to be well built. There were newspaper articles about Habitat houses performing better than neighboring houses in Hurricane Andrew. In an effort to better benefit the homeowners they serve, Habitat has recently started a formal program to build even better, code-plus homes that could stand up to local hazards and document the methods used during construction. The name of this new program is Habitat Strong. Simpson Strong-Tie is proud to be a major sponsor of the program.

Habitat Strong actually began as a pilot project funded by Travelers Insurance that built 20 disaster-resistant homes in Alabama, Mississippi, New York and Connecticut. The success of that project convinced Habitat of the importance of building stronger, more resilient homes in all parts of the country. Starting from those regional hurricane-inspired efforts, the Habitat Strong program is now being used by more than 48 affiliates throughout the country, as shown on this map.

Habitat for Humanity Habitat Strong affiliate map.

According to Habitat for Humanity, “The Habitat Strong program is designed to promote the building of homes that are more durable, resilient, and physically stronger. The need for stronger homes has become increasingly apparent, and through Habitat Strong’s fortified codes-plus building practices, we are able to strengthen homes’ building envelopes, which enable[s] them to better withstand natural disasters in every region of the country. This program was developed specifically for the Habitat model to be affordable and volunteer-friendly, while offering benefits to partner families that will last for years to come. Based on these principles, we believe that building homes Habitat Strong is the right thing to do!”

Habitat for Humanity has established a set of construction standards for Habitat Strong that are based on the Insurance Institute for Business & Home Safety® (IBHS) FORTIFIED Home™ program. The FORTIFIED program is a scientifically developed, systems-based incremental approach for creating stronger, safer homes. There are three levels of FORTIFIED Home™ designations: Bronze, Silver and Gold. Each level builds upon measures at the preceding level to increase the disaster resistance of the home. You can take a look at the FORTIFIED Home standards on the IBHS website at www.disastersafety.org.

There are now three separate sets of FORTIFIED Home™ standards: Hurricane, High Wind & Hail, and High Wind. In general, the three levels consist of the following:

Bronze:

  • Strengthen roof deck fastening by using 8d ring-shank nails in a closer-than-normal nailing pattern.
  • Apply a secondary water barrier to the roof deck so there will still be protection from water damage even if the roof covering is blown off.
  • Install a roof covering that is rated for high winds and, if appropriate, hail forces.
  • Prune nearby trees to prevent damage to the home during a wind event.

Silver:

  • Complete all requirements for Bronze.
  • Brace gable ends over 4′ tall and ensure they are sheathed with a minimum thickness of wood structural panel.
  • Anchor wood frame chimneys to the roof structure.
  • Anchor attached structures, such as porches and carports, from the roof to the foundation.

Gold:

  • Complete all requirements for Silver.
  • Provide a continuous load path for wind forces from the roof to the foundation. In a normal 115-mph wind zone, the load path is to be designed for at least 140 mph.
  • Provide a garage door that is rated for high winds.

Habitat for Humanity is recommending to their affiliates that homes built in coastal areas be built to the IBHS Gold standard for hurricanes, and those built in inland areas be built at a minimum to the Bronze or Silver standards for high winds. The Habitat homes that meet the Bronze or Silver standards will be certified as Habitat Strong. Habitat homes that are built to the Gold standard will be certified as Habitat Strong+.

Simpson Strong-Tie is proud to be assisting Habitat for Humanity with Habitat Strong. In January, we hosted a training for Texas affiliates that was offered by Habitat and IBHS staff at our Houston training facility. We also donated connectors for a demonstration home at Michigan State University that we helped design.

If you would like more information on Habitat Strong, contact HabitatStrong@habitat.org. To learn how you can help Habitat for Humanity, visit www.habitat.org/getinv/volunteer.

Are you aware of any other programs for strengthening affordable housing? Let us know in the comments below.

 

 

 

Impact Community Resilience as a USRC Member and Certified Rater

The U.S. Resiliency Council (USRC) recently launched its Building Rating System for earthquake hazards. The Rating System assigns a score of from one to five stars for three building performance measures: Safety, Damage (repair cost) and Recovery (time to regain basic function).

US Resiliency Council header

This first-of-its-kind building performance rating is based on decades of earthquake engineering research and observations of earthquake damage and recovery. It will become an important component of future sustainable and resilient community goals. The USRC will expand its building performance ratings to include other natural hazards such as hurricanes, tornadoes and floods in the coming years.

Building damaged by natural disaster

With the USRC rating system, users will receive reliable and consistent information about a building’s expected performance during an earthquake and the estimated speed of its recovery afterwards. They can use this information to help them make decisions about purchasing or leasing buildings in which they live, work or invest, or about financing or insuring these buildings. The USRC Rating System also allows businesses and communities to plan and prepare for disasters by giving them data on the likely performance of their building stock. With the support of its Sustaining Members, the USRC will play an important role in long-term strategic capital and disaster recovery planning for communities and businesses. With the USRC Rating System, owners can specify the desired level of performance for their important facilities, to ensure that they not only survive, but also continue operations after a disaster in accordance with their expectations.

The steps to obtain a USRC Verified or Transaction Rating are as follows.

  1. Select Rating type The building owner or building jurisdiction determines the desired USRC Rating: Transaction or Verified.
  2. Select Certified Rating ProfessionalThe building owner selects and contracts with a USRC Certified Rating Professional (CRP) to complete a seismic evaluation of the building. Owners can search for CRPs and see what the requirements are for individuals to be USRC-certified at www.usrc-portal.org.
  3. Perform detailed evaluation and determine preliminary Rating The CRP performs a seismic engineering evaluation of the subject building using one of the USRC-approved evaluation methodologies, which include ASCE 41 and FEMA P-58, and translates their findings into a three-dimensional rating using the USRC translation matrix. A simplified version of the translation matrix for an ASCE 31/41 assessment is shown below:USRC translation matrix
  4. Submit evaluation and Rating to USRC The CRP’s evaluation report, proposed Rating and application fee are submitted to the USRC along with a request for either a Transaction or a Verified Rating.
  5. USRC performs review and issues Rating The USRC reviews the submission for completeness. The USRC will then either issue a Transaction Rating certificate, or one of its USRC Certified Rating Reviewers will perform a technical review before issuing a Verified Rating certificate.

Becoming a USRC Certified Rating Professional or Reviewer:

The minimum requirements for becoming a USRC Certified Rating Professional include an educational background in structural engineering, five years of relevant building evaluation experience as a licensed Professional Engineer and professional references.

The minimum requirements for becoming a USRC Certified Rating Reviewer includes either holding a Structural Engineering license followed by five years of relevant experience, or a Professional Engineering License followed by 10 years of relevant experience.

Details of the application process and other requirements for certification are provided on both the USRC website, www.usrc.org, and the USRC portal, www.usrc-portal.org. The cost to become a USRC Certified Rating Professional or Reviewer is $600 for individuals with a $100 annual renewal fee. Individual and corporate members have discounts on certification.

Building Inspector Looking At New Property

USRC Membership

The U.S. Resiliency Council is a growing 501(c)(3) nonprofit organization with the vision of a world in which building performance in earthquakes and other natural hazards is better understood by building owners, tenants, financial institutions and communities. Corporations, organizations and individuals who are stakeholders in the built environment and who have a passion for improving the resiliency of our nation, have the opportunity to support the USRC through sustaining memberships. With the help of its sustaining members, the USRC will encourage:

  • Increasing market demand for better-performing buildings
  • Fostering collaboration among diverse stakeholders and technical experts
  • Promoting integrity, stability, consistency and transparency of rating systems
  • Educating and advocating for safe buildings and a better public understanding of building performance

USRC Membership List

USRCs members include many of the largest and most respected professional A/E firms and engineering professional societies in the country. Membership is open to all companies, individuals, communities and other stakeholders in the built environment. Information on joining the USRC can be found at the USRC website www.usrc.org.

What contributions from engineers are necessary to help create more resilient communities? Let us know in the comments below.

What Factors Contribute To A “Resilient” Community?

The world has seen many increasingly catastrophic natural disasters in the past decade, including Hurricane Katrina (Category 3) striking New Orleans in 2005, 2010’s 7.0 magnitude Haiti and 8.8 magnitude Chili earthquakes, the 9.0 magnitude Japan earthquake along with the Christchurch earthquake (6.3 magnitude) in 2011, the tornado outbreak in 2011 which included an EF4 striking Tuscaloosa, AL and a multiple-vortex EF5 striking Joplin, MO. We also saw Category 2 Hurricane Sandy, the largest Atlantic hurricane on record in 2012 and the EF5 tornado striking Moore, Oklahoma in 2013.

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