Page 19 - Green Builder's Resilient Housing Design Guide 2018

CREDIT: NATIONAL GUARD

Preparing for the worst. Changing weather patterns are making scenes like this Hurricane Harvey-related one all-too-common nationwide. They’re
also a signal flare for builders, who need to prepare even more for natural disasters.

7 Improper elevation of habitable space and utilities relative to flood risks
resulted in structural and contents damage.

LEVATED HOMES TEND to survive flooding much Bottom line: The depth is key. It should be noted, however, that
better than those on low-lying foundations. Flood vents pilings do not guarantee an unscathed structure after a storm:
in elevated reinforced block or monolithic foundations “A study of Topsail Island found that 98 percent of post-1986
can save a home, if flood levels adhere to “normal” levels. oceanfront houses (200 of 205) remained after the hurricane.
E But let’s assume future storm surges WILL exceed current Ninety-two percent of the total displayed no significant damage
height estimates—and focus on the use of pilings. to the integrity of the piling foundation. However, 5 percent were
After Hurricane Fran in 1996, FEMA conducted a study of what found to have leaning.”
happened to stilt homes. The agency found that: FEMA tested the leaning buildings to find out what happened.
“A significant reduction in building losses was observed in simi- They discovered that among the leaning buildings, “none of the
larly sized oceanfront buildings constructed after the North Caro- leaning pilings tested met the required piling embedment standard.
lina Building Code was amended in 1986 to require a minimum Many were much shorter.”
embedment to 5 feet National Geodetic Vertical Datum (NGVD), In other words, the contractors failed. Out of this research, the
or 16 feet below the original ground elevation, whichever is shal- suggestion was made that pilings be embedded to a minimum depth
lower, for pilings near the ocean.” of 10 feet NGVD, without exception.

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