Bob visited with Beth Judge, coastal hazards specialist for the S.C. Sea Grant Extension Program, at 113 Calhoun Street: A Center for Sustainable Living to learn more about methods and materials used in buildings to make them more resistant to wind, hurricane, and flood damage. The 125-year-old house in downtown Charleston, was heavily damaged a decade ago by Hurricane Hugo.
Now in the last five years the house, which was donated to this project by the city of Charleston, has been reconstructed and retrofitted as a demonstration house to educate homeowners and builders about better ways of mitigating the effects of flood and high winds and even earthquakes in this part of the country. Additionally the project team will use the house as a lab to test out new technologies and see how they'll perform in Charleston. The 113 Calhoun project is a partnership of the S.C. Sea Grant Consortium, Clemson University Extension Service, the City of Charleston, the Federal Emergency Management Agency, South Carolina state government, and Charleston County.
As they toured the house, Beth pointed out the new foundation, sustainable construction materials, unique insulation installation, and reinforced structural connections. Of particular note was an innovative "high-wind retrofit bracket," which homeowners can install to reinforce structural connections without removing sheetrock from the walls.
During the reconstruction the house was elevated and the foundation rebuilt. Since the house is in a seismic zone, the house has poured concrete footings in reinforced concrete block, which are all bolted to the house sill. For appearance sake brick veneer was added to hide the concrete piers that support the house.
Based on research from a Clemson Masters Degree in Civil Engineering student which determined that elevating a house just seven inches could eliminate damage from 60% of the flooding events in Charleston, the house was raised about a foot higher than it originally stood when the new foundation was constructed.
Metal Strapping
Metal strapping can be found in all areas of the house. The windows are strapped onto the frame of the building. Even the fiberglass columns and the porches are strapped to the foundation.
The majority of insulation used in the house is blown in cellulose. Recycled newspapers are blown into the walls of the house creating an effective insulation. However, since the house is located in a flood zone, the lower sections of the walls are insulated with rigid foam insulation that can be reused.
In order to preserve as much of the original structure of the house as possible, the builders used metal strapping to reinforce the old wood. An epoxy was also applied to strengthen the wood where there were rotting problems in the original framing members. Where necessary floor joists were sistered with new joists to reinforce their strength.
Because this was a renovation rather than new construction, the house was fitted with High Wind Retrofit Brackets, invented by Clemson University grad student Edward Sutt and his professor Dr. Timothy Reinhold.
Windstorms cause tremendous damage because extreme forces are created as the wind passes over and around a home. Traditionally the only way to strengthen a wood framed house to resist the force of the wind was to remove the interior or exterior finishes to get at the wood frame members and directly install conventional metal strapping. While this is a daunting process in a wood framed house, it is exponentially more difficult if the home is built of concrete block and stucco. The Retrofit Bracket allows the homeowner to reinforce the connections in his house without taking it apart.
Retrofit Bracket
The bracket can be mounted directly over the drywall, paneling or exterior siding in a home and simply secured to the structural members of the house with lag screws. The extruded aluminum bracket is reinforced to provide excellent load transfer to the connection. Its unique patented shape can provide capacities up to four times the original connections capacity. The finishing touch is a piece of crown molding that fits over and camouflages the bracket to give the newly strengthened house a dressed up look.
The Retrofit Bracket can be installed on the interior or exterior to reinforce the roof to wall connection, as a baseboard on the floor of an upper story connected to another bracket on the ceiling of a lower story as a floor to floor connection and at the base of the first story wall to transfer loads from the wall to the foundation.
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