FLASH Introduces New Resilient Design Guide to Improve Home and Community Resilience
By Donn Thompson and Jamie Farny
An increasing number of U.S. households are located in areas that are affected by flooding and high winds. Based on the findings of the 2010 U.S. census, more than half of our population now resides in coastal counties. There is a tangible benefit to making homes in these areas more disaster-resilient. Not only can this enhance occupant safety, it can protect property and reduce costly repairs following catastrophic events.
FLASH, the Federal Alliance for Safe Homes, is the country’s leading consumer advocate for strengthening homes and safeguarding families from natural and manmade disasters. FLASH continually looks for ways to move the U.S. toward better practices for residential construction. Their latest publication, Resilient Design Guide – Concrete Construction Edition, is the second in a series of manuals that are intended to help anyone looking to build better, especially in coastal areas. This guide is geared to everyone from the experienced contractor, to volunteer groups involved in mitigation and recovery, to homeowners interested in being informed consumers. It explains how concrete wall and floor systems, combined with durable wind- and impact-resistant finishes and enhanced framed roof assemblies, can provide cost effective ways to better protect homeowners. In addition to the “how to” of featured leading practices, the guide provides specific context about “why” a more resilient approach is important.
Creation of the guide started with a daylong design charrette hosted by the New Jersey Institute of Technology. Providing a forum to discuss the critical components necessary for next generation coastal construction, the charrette brought together several key groups: local design professionals affiliated with the New York Chapter of the American Institute of Architects, mitigation experts from the Federal Emergency Management Agency and the National Weather Service, and product representatives for various robust construction materials.
THE GUIDE’S APPROACH
Recommendations from the participating experts were incorporated into the guide, starting with an introduction to the types of forces at work when a house is subjected to the significant impacts of high wind or flooding. A 150 mile per hour wind pushes on the side of home with the same force as the weight of snow piled three feet high on top of the roof. The house has to be designed as “a whole system” so various components including the walls, floors, roof and foundation all work together to resist the forces to which it will be subjected.
Three levels of performance are identified in the guide:
- Code Compliant Conventional Construction
- Higher Local Hazard Construction
- Resilient Construction
Roofs and foundations are the focus of the first two performance levels. Code compliant construction is typically only strong enough for wind speeds of less than 100 miles per hour and lacks enough strength to resist flooding. For higher local hazards, where wind speeds are greater than 100 miles per hour and where the potential exists for flooding, enhanced construction details can significantly improve performance.
Recommendations for resilient construction―the guide’s highest level of performance―feature concrete walls and floor assemblies combined with more resilient wood-framed roof assemblies. This represents the most cost effective approach to providing a far greater resilient overall structure, often significantly reducing potential for severe damage.
VALUES AND BENEFITS OF CONCRETE
Concrete offers high performance in the face of disasters and also delivers benefits for everyday life, such as energy efficiency and low maintenance. Detailed product information is provided for four major concrete wall systems: concrete masonry, conventionally formed concrete, insulating concrete forms and precast concrete systems. Additional information describes the value and benefits of concrete floors, built conventionally with removable forms, or with stay-in-place insulating forms, or with precast concrete planks.
Building better involves more than just the structural system for the home. Recommendations for various additional components are covered. Windows and doors of appropriate design, with appropriate pressure ratings and impact resistant glazing are highlighted along with recommendations for appropriate flashing. The impact resistance of common exterior finishes varies, so making the right choice based on anticipated debris hazard is critical. Likewise, garage doors can be particularly vulnerable, so careful selection of those is important as well.
Loss of power due to trees or limbs falling on power lines can affect the comfort and safety of occupants. Standby generators can virtually eliminate the problem, especially when used along with insulated concrete building systems.
PLENTY OF RESOURCES
Readers are given plenty of references and web sites where they can find more in-depth resources covering the many products and systems described in the guide. The language and graphics are clear, concise and easy to understand, even for those who are less familiar with construction.
The Guide in Practice: The #HurricaneStrong Home
FLASH partners including the Portland Cement Association, BASF – The Chemical Company, Huber Engineered Wood and +lab architects + experimentation have collaborated on a demonstration project that literally builds on the recommendations contained in the Resilient Design Guide – Concrete Construction Edition. Located along the New York City coast in an area called Breezy Point, the project incorporates the many resilient construction recommendations.
The two-bedroom home with 1,375 square feet of living area will be built with a conventionally formed concrete foundation to raise the living level above the local design flood elevation. Insulated concrete form floor and exterior walls provide strength and energy efficiency. Wood roof framing, enhanced with spray foam insulation for warmth and additional wind resistance will support weather resistant roof sheathing. Concrete roof tiles and fiber cement siding along with impact resistant windows protect the exterior.
During Superstorm Sandy, residents of Breezy Point were subjected to high winds and flooding. Further devastation occurred when an electrical fire destroyed more than 130 homes. The #HurricaneStrong Home rebuild is an important element in restoring a community that was hit hard a few years ago and is likely to be hit again. Once complete, this new home with all of its resilient features will provide its owner with added comfort and peace of mind.
For more information and to download a copy of the new guide visit www.flash.org.
This article appeared in our December 2016 edition.