Disaster Resistance
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Concrete Homebuilder Helps to Fortify Florida Concrete House Stands Up to Katrina Concrete Home Stands Up to Tornado ICF Wall Survives 90 MPH Car Crash
Concrete House Stands Up to Katrina
The Sundbergs' home, shown in the yellow circle, The Sundbergs had been building their fully mitigated home for eight years, and it was 85% complete, when Hurricane Katrina slammed into their area on Aug. 29 with a huge storm surge and reported sustained winds of 125 mph. The water reached an elevation of 28 feet. After the winds had died down and the water retreated to the Gulf of Mexico, the Sundbergs found that their home had survived the storm largely intact, with some blown-out windows, lost materials and missing upstairs panels. Now they are focusing their efforts on finishing the building before the next storm strikes. “This is where our heart is,” said Scott Sundberg, a graduate of the University of Alabama and a structural engineer for 25 years. He used his experience with structural physics and design to build the home, which he and his wife Caroline call Shadowlawn. Before breaking ground, Sundberg did his homework. He studied the Federal Emergency Management Agency's (FEMA) Flood Insurance Rate Maps, Florida building codes and the storm history of the area, and he visited abandoned home sites where scars of Hurricane Camille were still visible. The information from his research motivated him to build the home to withstand severe storms. In 1998, Hurricane Georges dealt a glancing blow to the Sundbergs’ area of Pass Christian in Harrison County, which is one of the three counties in Mississippi hardest hit by Katrina. When Georges struck, the Sundbergs had just put the forms up and rebar in place for the carport slab. “I became even more convinced [after Georges] that it had to be right, that it had to withstand a Camille,” Sundberg said. Hurricane Camille was a Category 5 storm that raged across the Gulf Coast in 1969, leaving a wide swath of destruction. A native of Thornton, Illinois, where there is a major concrete quarry, Sundberg said that “concrete has been in my blood since I was young.” Accordingly, when it came to building his dream house, he used concrete as the main building material. The result is a sturdy house constructed of insulated concrete form (ICF) walls—reinforced both horizontally and vertically—post-tensioned concrete slab, concrete columns and a concrete roof on top of cold rolled metal panel sections. The Sundbergs’ house has spread footings, with concrete members to distribute the load to the soil, and a 4-foot-high beam-wall down the center. There is connectivity through the house from the roof down to the third floor, on to the second floor, and then to the carport. The house is also built to “perform elastically” and to withstand winds of between 180 and 200 mph. The bottom of the beam of the first floor living space is 25.4 feet above sea level, according to the National Geodetic Vertical Datum (NGVD). The carport elevation of the Sundberg home is 14.8 feet, which is above a 14-foot base flood elevation (BFE) for the area. The slab-floor level of the house is the carport, and it has a small interior room. This space had breakaway walls which “blew away perfectly,” said Sundberg. The windows that were installed in the Sundberg home were vinyl gliders, which are not hurricane resistant. The few windows that did blow out will be replaced and hurricane shutters installed as planned, adding another safety measure to the home. Sundberg’s home also has a second floor area designed as a “safer” room, with walk-in closets sheathed in plywood and framed with 6-inch 18-gauge metal studs at 12 inches on center. The room is not, however, a Safe Room per FEMA 320 Guidelines, which are recommended because they provide homeowners with guidance to assess their tornado risk. Sundberg firmly believes that adopting proper codes, with respect to the BFE, “could prevent 75% of the damage” from hurricanes. “As compliance increases, damage is less,” he adds. Sundberg has been following the stronger codes that were put in place in Florida in the mid-1990s following Hurricane Andrew. The Sundbergs’ home, which stands roughly 350 feet from the shoreline, is fully insured. The couple has yet to settle their flood insurance claim. They had renters insurance for the contents of their rental home in Long Beach, which was destroyed. Unfortunately, they did not have flood insurance, so they lost everything at that property, and their belongings and precious records were not insured against flood. The Sundbergs had to replace their cars, and all of the finished landscaping at their new home was destroyed. Since Katrina, the couple has been living in an 8-foot by 33-foot trailer, with two 3-foot slideouts parked next to their driveway. When they visited their new home after Katrina, Sundberg looked for cracking, spalling and displacement. He was relieved to find no signs that the structural integrity of the home was compromised. “Using concrete adds about 10% to 15% above the cost of conventional construction,” stated Sundberg. In this case, it proved to be a wise investment. Thanks to NAHB’s Concrete Home Building Council for this article.
Concrete Homebuilder Helps to Fortify Florida “Our Houses Don’t Blow Away” is the motto for RFB, Inc., a South Fort Myers, Florida, homebuilder that has just completed the first home in Lee County to be certified under the Institute for Business and Home Safety (IBHS) “Fortified ... for Safer Living®” program. This home has already been sold and there are several more under construction.
The “Fortified” hurricane resistant homes are built to withstand wind speed in excess of the Florida Code requirements. RFB uses an ICF (insulated concrete form) wall system. The result is a strong and very energy efficient home. The roof decking measures 5/8 inches (thicker than normal), which is nailed down with ring-shank nails for resistance to lift. The seams of the plywood are sealed with a waterproof shield and then covered with felt, while the shingles are rated for 130 mph. Low-E glass windows are used, which are designed for higher than required winds. These help the homes achieve their Energy Star rating. The attics are sprayed with at least 5 inches of Icynene, a foam insulation, applied directly to the underside of the roof sheathing, thereby allowing the air conditioning ducts to run in conditioned air, greatly improving the efficiency of the HVAC system. This also allows the home to use a smaller A/C unit, saving the homeowner money.
According to Joe Redburn of RFB Homes, Hurricane Wilma recently tested 5 of their homes. “The only damage we had was three ceiling fans blown off the lanai on one of the houses,” Redburn said. Currently, homebuyers can choose from three models. All models come with Fortified and Energy Star ratings.
Photo Courtesay of Stu Oates of Builders Wholesale
Concrete Homes Newsletter
Stoughton, Wisconsin, residents picked up the pieces after a tornado recently leveled most homes in the area. One home is still standing amidst the rubble: a concrete home, currently under construction in an upscale Stoughton neighborhood, built with insulating concrete forms (ICFs) from Reward.
When the F-3 tornado tore through town, the home was only partially constructed. The structure was under roof, with windows installed, and brick cladding had begun. First reports were that the only damage the home sustained was to the garage roof. It was stated later that the screened-in porch was lost, and all windows were broken. These reports were confirmed when Boyd Coleman, a structural engineer, was called in to inspect the damage. “Although I’m familiar with ICF construction, this was the first I had seen of an ICF building that had gone through something like this.” Coleman added, “I was surprised to see so much debris stuck in the foam.” Coleman found that the ICF walls did not move. There was damage to the top plate where the garage roof was blown off, but none to the concrete. Where Simpson hurricane clips were used, the roof trusses were intact. Debris from the storm was found 75 miles east in Milwaukee. (Flying debris is the primary cause of injuries and fatalities during tornadoes and hurricanes.) Meteorologists believe 26 tornadoes touched down in a 100-mile-long area. Wisconsin typically has 21 tornadoes in an average year. Construction resumed on the 3-story, almost 5,000 square foot house. The roof and porch were replaced, and the entire roof had to be reshingled. Windows and doors also needed replacement, but construction was set to be back to pre-storm progress two to four weeks after the event. According to the builder, Randy Settersten, “I’d really like to get these folks into their home before Christmas.”
Concrete Homes Newsletter
ICF Wall Survives 90 MPH Car Crash
“I believe the PolySteel wall saved my life,” claims Mr. Ray Demczyk of Cape Coral, Florida. Early on the morning of June 26, 2004, as Mr. Demczyk and his wife slept inside their ICF home, a potential tragedy was unfolding outside. At approximately 2:00 A.M. an intoxicated driver was speeding down the Demczyk’s street, fell asleep at the wheel, and never noticed when his Pontiac Firebird left the road, became airborne, and slammed into the exterior wall of the Demczyk’s residence at a speed of 90 miles per hour. The ICF wall’s sound class rating of 48 offered the sleeping Demczyks no clue of disaster. Stirred awake by a light thud, Mrs. Demczyk left her bedroom to identify some household object that had fallen to the floor. To her great surprise she found a set of headlights shining brightly through her living room window.
The ICF wall’s strength was evident once the cleanup had been completed and damage was assessed. A 3 ft x 5 ft section of the wall’s exterior finish suffered the impact of the crash, while the ICF wall itself remained unscathed. PolySteel Distributor Ed Easter was involved with the construction of the 5800-square-foot, two-story, stucco home, built in 1997 at a cost of $196,000. “It should cost me less than $800 to complete repairs to my stucco finish,” Demczyk said. Emergency workers on the scene said that the speeding vehicle would have penetrated the residence had the walls not been concrete.
Though the car was totaled, the driver survived the collision with no reported injuries. Mr. Demczyk and his wife have only minor repairs to make and can continue sleeping peacefully, assured of the safety of their concrete home. *Story and photos courtesy of American PolySteel. |
