Subject: [Homestead] Houses, build them to minimize risk
Date: Wed, 22 Sep 2004 21:55:50 -0700
That means hurricant-proof, fire and flood-resistant---you can
self-insure a really safe house and your unspent insurance premiums will
pap for any added construction cost---and you don't have to fight a
promise-to-pay insurance company in court to force them to pay, either.
(Photograph)
STILL STANDING: Jonathan Zimmerman designed this house in Pensacola
Beach, Fla., to withstand 300-m.p.h. winds. It was undamaged by recent
hurricanes.
JONATHAN ZIMMERMAN
Houses that defy hurricanes
By Neal Learner | Correspondent of The Christian Science Monitor
Florida snowbird Mary Frances McKenzie considered herself fortunate
after hurricane Charley blew through recently. Her winter home in Spring
Lake, Fla., withstood the mammoth storm unscathed. The house down the
block did not.
The roof on that cement-block stucco villa blew its top and crashed into
her sister-in-law's back porch. "It caused a lot of water damage," says
the Indiana native of her in-law's home, just two doors down.
Fortunately, many new homes in hurricane-prone areas today are built to
codes to avoid such an unpleasant scenario. These include everything
from domed homes that are supposed to survive 300-mile-per-hour winds to
safety innovations on more conventional houses.
While progress has been made, there is still much that could be done to
mitigate damage, experts say.
The winds of a major hurricane can rip apart a poorly built house, or
inflate it like a balloon, says Chad Morris, associate director of the
Wind Science and Engineering Research Center at Texas Tech University in
Lubbock.
"That usually begins with a window or door that fails from the wind
pressure," he says. "The air is then allowed to enter into the house,
which lifts the roof off the home. Once that happens, it just blows the
guts out of the inside. Sometimes it will blow out the back wall."
Ten years ago, the weakest link was roof sheathing and its attachment to
the roof, says Tim Reinhold, of the Institute for Business and Home
Safety, a nonprofit group funded by the insurance industry. "In
[hurricane] Andrew, probably 90 percent of homes that had damage had
some sort of roof covering damage. What we saw in Charley was that
people had begun to attach roof sheathing better."
The big issue now is in the attachment of soffits, the vinyl stripping
that covers the space where the roof meets the walls. This material is
just being stuck in there and not being attached according to
specifications, he explains. "As the wind blew in the house, the roof
was staying on, but the soffit material was blowing up and allowing rain
to blow right in over the wall and into the ceilings of the house," Mr.
Reinhold says of his observations after Charley. "Then you get all of
your insulation wet, your ceiling starts to collapse, and you've trashed
your house."
Other weak links are of the human kind. Competitive pressures are
pushing builders to erect homes quickly in booming coastal communities.
Because of that competition, some builders will cut corners, says Ben
Sill, director of the general engineering program at Clemson University
in South Carolina.
Building inspectors, meanwhile, may show up in the morning to inspect
roof work just starting, only to return later that day to find the
asphalt shingles already up, says Mr. Sill, former director of Clemson's
wind-load test facility. "Unless you have some guy standing there the
whole time ... you just have to take a lot of people's word that they
did it right."
The right way to install a roof, for example, includes attaching plywood
with nails at six-inch intervals along the edges and eight to 12 inches
up the center, says Charles Miller, an editor at Fine Homebuilding
magazine and a former homebuilder. Many of the homes that sustained the
most hurricane damage used staples that missed their mark, he adds.
"They're not equating the results of bad building practices with the
reality of what that storm is going to do with the house."
One basic safety feature that consumers should look for is hurricane
strapping, flat metal strips that literally hold the trusses and rafters
to the walls. Another important consideration is whether the house has
shutters. And tiles need to be either screwed to the roof or embedded in
a mortar patty designed to adhere to the tile, Miller says, adding that
such measures don't add that much to the cost of the house.
If consumers demanded hurricane safety features, as they eventually did
with car air bags, then builders would respond, Sill says. He wants a
national wind-hazard mitigation program, much like a current program for
earthquake hazards.
Congress is considering providing $60 million to establish a national
wind-hazard mitigation program, Reinhold adds.
Is it possible to build a hurricane-proof house that doesn't look like a
concrete bunker? Mark Sigler certainly thinks so.
After hurricane Ivan hammered nearby homes last week, his "dome home" on
the Florida Panhandle survived the full brunt of the deadly storm with
barely a scratch, Mr. Sigler says.
More than 80 percent of the houses on the barrier island were destroyed,
including those on both sides of his home, says Sigler. The gracefully
arched, reinforced concrete house sustained only minor damage, including
to a staircase that blew away as designed to avoid damaging the structure.
The house was designed by San Francisco Bay-area architect Jonathan
Zimmerman, who says the Sigler home proves that this is the strongest,
safest way to build a house.
Construction of a domed home starts with a balloon inflated to the shape
and size of the house. Rigid foam insulation is then sprayed on the
inside surface of the inflated form, to which steel bars are attached in
a crisscrossing pattern. Concrete is sprayed over the bars and
insulation, with spaces left for doors, windows, and other architectural
design spaces in the home.
Winds travel through the shell and wind loads are transferred down to
the foundation.
Sigler's dome home weighs about 850 tons, compared to about 30 tons for
a similar-sized wood house. The cost of building such a home is
comparable to other designed homes, says Sigler, who adds that it's an
excellent investment: "These homes are designed to last seven generations."
Sigler and his wife, Valerie, won a $245,000 grant from the Federal
Emergency Management Agency to help build the house. Florida has lost an
estimated $45 billion to $50 billion from the three recent hurricanes.
Since the trio of hurricanes hit in rapid succession, Mr. Zimmerman has
seen a jump in the number of visits to his website, www.zdomes.com
<http://www.zdomes.com>. Work is under way to build one of his dome
homes in an avalanche zone in Alaska.
"We live in a crisis-reactive society," he says. "These crises have
really made people change the way they think and perceive things. If
anything is accomplished by this, I am hoping that people will revisit
the idea of what a home needs to be and what a home needs to look like."