Warren and Pam Adams’ home‚ rebuilt to newer codes following Hurricane Rita three years ago‚ was the only residence to survive Hurricane Ike in the coastal community of Gilchrist‚ Texas. (Jocelyn Augustino/FEMA)
Learning from Buildings that Survived
Rebuilding may be months, or even years, in the future. East Texas coastal
communities face hard choices about whether, and how, to return to ocean fronts
whose face has been redrawn by the storm. But there’s hope to be found in the
handful of homes still standing after Ike’s wave passed.
Retired Florida
homebuilder Richard Reynolds visited Gilchrist, Texas, to inspect ten houses
that survived the storm. Built to the above-code standards of the Institute
for Business and Home Safety’s “Fortified … for safer living” program, the
houses were elevated above the flood level. Wave and tidal action detached and
washed away staircases set below the storm surge flood level, but left the homes
intact. According to Reynolds, these homes will be serviceable as soon the
stairs are replaced and power is restored — although their location now looks
more like Mars than like the pleasant beach community it was before the storm,
and no one knows when local authorities may once again allow occupancy.
Although the houses came through in good structural shape, Reynolds did
note a few issues, which the IBHS Fortified program’s engineers are likely to
respond to in future program guidance. For one thing, says Reynolds, “every
single house” lost some roofing shingles. That’s to be expected — roofing
manufacturer standards don’t even rate asphalt shingles to maximum
hurricane-force winds. That’s why IBHS program standards for new construction
require a secondary weather barrier that will stay in place in spite of the
wind, even if the asphalt shingles blow off. Peel-and-stick membrane applied to
sheathing joints to meet this requirement for these houses proved its worth,
says Reynolds — almost none of the homes had roof leaks, despite some
significant loss of shingles.
Reynolds did observe wind-blown rain
intrusion at windows and doors — even in cases where the windows were protected
by roll-down storm shutters. While it may be hard to make windows and doors any
tighter than they already are, Reynolds suggests that builders may be able to
devise some kind of drainage or protection to contain and drain any water that
does blow in at cracks between the frames and the doors or the window sash. In
coming months, says Reynolds, IBHS will be evaluating a range of methods that
might be useful in reducing this type of water intrusion.
On a beach scrubbed clean of almost every mark of
human habitation, ten surviving homes, built to the standards of the IBHS
Fortified program, provide dramatic evidence of the value of modern
storm-resistant construction methods. (Photos by Richard Reynolds)
Hurricane-force winds tore some shingles off all the
Fortified houses. But strips of peel-and-stick membrane applied to sheathing
panel joints prevented rain intrusion from ruining building interiors.
Winds pushed some rain water in around windows and
under doors. However, wood-based wall panels and wood flooring in the homes
dried out quickly after the storm passed, and did not sustain significant mold
damage.
Another item worth noting is that none of the houses he
looked at had gypsum-board walls or ceilings, says Reynolds — they used various
wood or wood-composite panel products for interior wall and ceiling finishes.
They also had wood floors and no carpeting. Reynolds says this spared the homes
from any significant mold growth, even where some water did intrude. “The mold
was minor,” he says. “They threw away a few throw rugs, and that was it.”
There were originally 13 Fortified houses on this stretch of beach, not
ten. Three were destroyed by wave action. Reynolds says those three were
probably impacted by floating debris from other, less well-constructed, nearby
structures. If this area does rebuild, the new generation of structures will be
governed by FEMA regulations that require builders to avoid methods that
generate such destructive floating debris.
Article from "Coastal Connection, A Coastal Contractor Special Report Newsletter", October 17, 2008.
Ike Report Draws Lessons from Success — and Failure
Six homes built to IBHS "Fortified" specifications survived Ike's storm surge.
About halfway up the pilings are the remains of utility decks set
slightly above the Base Flood Elevation (BFE). Though not intentionally
installed as "breakaway" elements, these lower decks were torn off by
waves. (Photo by Richard Reynolds)
When dawn broke after the midnight landfall of Hurricane Ike a year
ago, virtually every residence on the Bolivar Peninsula had been swept
away by the hurricane's overwhelming storm surge. Standing as lonely
exceptions on the scoured beach, however, were 10 out of 13 homes built
to the above-code standards of the Institute for Building and Home
Safety's "Fortified... for safer living" program. (The other 3 homes,
experts believe, were probably taken out when their pilings were struck
by floating debris from other nearby houses.)
A year of study later, IBHS has released a full report on Hurricane Ike. The report, "Hurricane Ike: Nature's Force Versus Structural Strength,"
draws on the lessons of the of the 10 surviving Fortified homes. But it
goes beyond those examples to examine a range of issues in
storm-resistant construction, making observations and recommendations
relating to key topics, including elevation, wind-driven rain
intrusion, roof attachment, and roof deck waterproofing. Also included
is a guide for retrofitting existing homes to boost their resistance to
wind, rain, and flood.
The key difference between the 10 surviving Fortified houses and
their vanished neighbors was the height of the buildings' first framed
floor. The builder installed open utility decks for the homes at an
elevation slightly above the area's 19-foot Base Flood Elevation (BFE),
then framed the floor systems for the first occupied stories 8 feet
higher than that. In the storm, the utility decks were lost to storm
surge wave action — but the foundation pilings, and the homes' occupied
space, survived.
IBHS argues that Ike demonstrated the
limitations of building at or near the Base Flood Elevation (BFE),
which is based on a statistically estimated 1% probability that water
will reach the established elevation in any given year. While this
likelihood is often described as a "100-year flood," wave action above
the BFE is actually a strong possibility far more frequently than every
hundred years.
The report notes, "A '100-year flood' means that the level of flood
water has a one percent chance of being equaled or exceeded in any
single year. However, it is well recognized in the engineering
community that coastal homes built to this level have a 26 percent
chance of being flooded or demolished over the life of a 30-year
mortgage. This chance increases to about 40 percent over a 50-year
period." Building higher than the BFE improves the building's long-term
odds of survival, explains IBHS: "For example, building to a 500-year
flood elevation reduces the chance of surge exceeding the base
elevation to about 10 percent over a 50-year period."
A scene of devastation surrounds the surviving Fortified homes.
Nearly every house on Bolivar was destroyed by Ike's storm surge. Many,
although sturdily built and properly attached to foundations, failed
because their elevations were insufficient to keep them above the wave
action of the surge. (Photos by Tim Reinhold)
Many
houses on Bolivar had been built with first floor systems at, or
slightly above, the area's official BFE. At dawn on September 13, 2009,
virtually all of those houses were gone — just as thoroughly destroyed
as structures set directly on the ground. Says IBHS: "When the vast
majority of buildings are built at or slightly above the 1 percent
annual probability of exceedance base flood elevation (BFE), all it
takes is an event (i.e., Hurricanes Ike, Ivan, Katrina, or Rita) with
surge levels a few feet above the BFE to wipe out the entire
community."
Article from "Coastal Contractor Online Magazine", September 30, 2009.
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