The Hurricane House in Chesapeake, Virginia, was built with the latest hurricane- and tornado-resistant features. All the windows in the home are both energy-efficient and wind-resistant, and can withstand winds up to 100 mph.

Workers assemble a wall of Styrofoam ICF forms, then move it into position, before the concrete is poured inside. With their solid concrete interiors, ICF walls can withstand high winds and other loads, making them ideal for disaster-mitigation building.

An ICF house built in Washington, Iowa, with the Reward Wall System easily withstood the May 15, 1998, F3 tornado that destroyed a tree on the lot and swept away most of a neighboring house.

This ICF home in Orinda, California, is reinforced to withstand a major earthquake. It is also fire- and smoke-resistant.

Building for disaster mitigation has another benefit, too--it saves money. Rita Calvan, director of the Federal Emergency Management Agency (FEMA) office in the IIIinois region, says, "For every dollar spent on mitigation, we realize two dollars of savings in aid to disaster victims." FEMA estimates that building to withstand disaster adds only 3%-5% to the cost of a building a new home. 

If recent trends in conferences and research are any indication, architects and builders are starting to take disaster mitigation building very seriously. For example, in October, Sandia National Laboratories, the American Institute of Architects, and the Architectural Engineering Institute of the American Society of Civil Engineers sponsored a conference at Georgetown University titled Innovative Technologies for Disaster Mitigation: An Architectural Surety. In November, a conference titled Durability and Disaster Mitigation in Wood Frame Housing and Durability Protocol Workshop, sponsored by the PATH Consortium for Wood Frame Housing and the Forest Products Society, took place in Madison, Wisconsin. Building scientists are also taking a closer look at disaster mitigation. For example, researchers at Johns Hopkins University have constructed a model home in Southern Shores, North Carolina, to better study the effects of hurricane-force wind on wood framing, steel framing, and concrete. Similar research is taking place in Florida and Virginia. All this activity points to the potential for a disaster-inspired building revolution in the next century.

The FEMA-sponsored Wind Summit in September 1998 inspired a public/private partnership to build a hurricane-resistant display home for the association's annual Fall Homearama. Known as the Hurricane House and built by contractor Jack Jackson, it is the display home at the Estates Carriage House, a new single-family community in Chesapeake, Virginia. The home had its first hurricane test in mid-September 1999--even before completion--when Hurricane Floyd paid the region a visit. Neither wind nor rain from Floyd--or from Irene, a later visitor--damaged the house in any way. 

The Hurricane House is built with wood frame construction and has insulation values that are higher than is typical in the region--R-15 in the walls, R-19 in the floors, and R-30 in the roof. It includes numerous features to increase hurricane resistance, including wind-resistant doors and double-glazed, laminated windows. These types of windows are energy-efficient, but they also will not shatter into dangerous shards--they crack into harmless pieces, as a windshield does. The house also features a 10 ft x 14 ft "safe room" that provides extra storm shelter but also serves as a walk-in closet off the master bedroom. This room has a 12-inch-thick reinforced-concrete ceiling built to survive winds up to 250 mph, as well as falling trees.

The Hurricane House was built with traditional construction techniques, but some alternative construction wall assemblies can provide substantial strength for hurricane resistance while also delivering inherent energy efficiency gains. The Portland Cement Association's Web site shows the results of various wall assemblies tested by the Wind Engineering Research Center at Texas Tech University (see Tables 1 and 2). 

Just as wind seeks out cracks, nooks, and holes to do its damage, earthquakes search for structural weakness. Earthquakes often involve more than just the familiar shaking and structural vibration; unstable soils may liquefy, and faults may literally split the earth. Thus, building designs that simply follow seismic codes do not guarantee against collapse or serious damage.

According to one expert in earthquake mitigation, professor V.V. Bertero of the University of California at Berkeley, design simplicity is one of the keys to earthquake-resistant construction. Although many other factors must be taken into account when building for earthquake mitigation, it is true that the simpler the building, the better it behaves in an earthquake. To build a home that can survive an earthquake, Bertero says, think of boats or baskets--carefully integrated and well reinforced, compact containers built of similar material and uniformly assembled. Avoid using heavy roofs or disproportionate height ratios that make the building top-heavy, and large asymmetrical plan areas that subject houses to excessive twisting or "soft-story" problems. Simple, symmetrical plans have both architectural and structural balance, and are less likely to break from twisting under earthquake stresses. Such houses are also easier to air seal and can easily be built to reduce opportunities for breaks and bridges in the thermal envelope.

For all construction, however, it is important to keep in mind that there is little point in using disaster-resistant materials if they are not properly connected. Poor quality control and poor workmanship are problems that can be caught and corrected through construction inspections, which also help to ensure the high-quality construction essential for energy-efficient home performance. 

Problems with snow and cold typically involve property damage, largely from frozen water pipes or ice dams. Insulating exposed plumbing and placing plumbing in interior walls are two straightforward methods of preventing pipes from freezing, and of course will cut down on water heating energy losses, too.

National megabuilder Centex Homes is looking at building with insulating concrete forms (ICFs) as a means to mitigate disaster damage. As a composite system combining concrete, structural reinforcement, and insulation, ICFs perform well under earthquake, fire, and hurricane conditions. ICFs also appear to perform well in the energy conservation arena (see "New Value for High-Mass Walls," HE Sept/Oct '99, p. 25; and "Foam Forms Bring Concrete Results," HE July/Aug '98, p. 27).

Structural insulated panels (SIPS) are made of another composite material that resists wind and earthquake forces (with all kinds of lateral loading, in fact) as well as conserving energy (see "SIPs Face the Skeptics," HE Mar/Apr '98, p. 13). Roger Rasbach, president of Provident Homes in Houston, Texas, feels he has improved the product with his composite system of steel and foam. His ready-to-assemble kit homes range from 800 to 3,000 ft² and are engineered to withstand 150 mph winds. 

Tilt Wall systems are precast, poured-concrete walls erected on-site with cranes. Judy Niemeyer, of Tierra Concrete Homes in Pueblo, Colorado, is a pioneer in this area. Tierra was both a 1997 and a 1998 Energy Housing Value Award Winner in the Innovative/Advanced Home Category. Tierra says its homes are 75% percent more energy efficient than standard homes because they use passive solar design, with the concrete walls forming part of the home's internal mass. Tierra's homes are also Energy Star rated and are part of NREL's Exemplary Building Program. However, tilt-up walls are poor performers in earthquake country.

Wally Sanger, of West Palm Beach, Florida, is another pioneer, with his Royall Wall system (see "Choosing a Basement Wall System," HE Mar/Apr '99, p. 37). Royall Walls have an R-value of 20 and will withstand an 85 mph impact and winds of up to 260 mph.

Autoclaved aerated concrete (AAC) holds much of the market in Europe and in earthquake-prone Japan. It is a lightweight solid block manufactured through the use of a special concrete mixture that employs an aerating agent, making the mixture "rise" somewhat like bread. Then the mixture is autoclaved--steam cooked in something akin to a giant pressure cooker. When finished, AAC can be cut into panels, slabs, or blocks. 

AAC is noncombustible, so it is very good for fire mitigation, and it emits no vapors. The walls have an R-value ranging from 5 to 12. AAC is resistant to heavy wind damage, thanks to concrete's ability to withstand projectile penetration. Ytong and Hebel, both German companies, are the primary U.S. producers.

Many of these types of wall system (except AAC, which is porous) may also be good for flood mitigation. Researchers at Oak Ridge National Laboratory are making plans to do research on this question. Using spray polyurethane foam insulation rather than fiberglass batt insulation in stick-built homes, and placing wiring inside a raceway on the face of the wall rather than within the walls, will also help to reduce damage from floods. What's more, spray foam insulation has a much higher R-value and provides improved air- and water-tightness, while using a raceway for the wiring reduces penetrations of the thermal envelope and makes for a tighter house. In fact, where water will leak through, so will air. Therefore, preparing for flooding problems--through careful sealing around window rough openings, for example--can improve energy efficiency as well. 

This reasoning is flawed, however, because it doesn't take a whole-house approach, which considers the many trade-offs that can be made through careful home design. Spending a little extra on first costs for energy efficiency measures will often dramatically lower the life cycle costs of the home, freeing up funds that can be put into disaster mitigation measures. For example, those hurricane straps might be paid for through energy savings from adding more insulation and properly downsizing the HVAC equipment.

A major benefit of all disaster-mitigation measures is that insurance companies are beginning to see advantages in promoting disaster mitigation, and are beginning to reward their customers who install such measures in their homes. According to Craig Horton, regional director of mid-Atlantic risk mitigation for United States Automobile Association insurance company, Florida homeowners who install storm shutters on their windows are eligible for a discount on their house insurance payments. Utilities, and lenders are also starting to take part in this trend toward disaster-mitigation building, Horton says, offering rebates and discounts to consumers who choose sturdier homes. 

With today's nightly news stories of earthquakes, hurricanes, tornadoes, ice storms, and heat waves, it is likely that the home buyers of tomorrow will come to expect more from their homes. 

Christina B. Farnsworth is a freelance writer and one of only three life members of the National Association of Real Estate Editors.

Robert Wendt, a building science researcher at Oak Ridge National Laboratory, and Colleen Turrell contributed to writing this article.

Table 1: Interior Frame Wall Wind/Missile Test Results
Wall Type	Test Wall Description	Speed of Debris	Results
Wood frame	5/8-in gypsum board interior finish, 2 x 4 wood studs at 16 in o.c., 3 1/2 in batt insulation, 3/4 in plywood sheathing, vinyl siding exterior finish	109 mph	The debris missile perforated completely through the wall assembly.
Wood frame	5/8-in gypsum board interior finish, 2 x 4 wood studs at 16 in o.c., 3 1/2 in batt insulation, 3/4 in plywood sheathing, 4 in brick veneer with 1 in air space	69.4 mph	The debris missile perforated completely through the brick veneer and the interior finish.
Steel frame	5/8-in gypsum board interior finish, steel studs at 16 in o.c., 3 1/2 in batt insulation, 3/4 in plywood sheathing, vinyl siding exterior finish	103.5 mph	The debris missile perforated completely through the wall assembly.
Wood frame	5/8-in gypsum board interior finish, 2 x 4 wood studs at 16 in o.c., 3 1/2 in batt insulation, 5/8 in gypsum board sheathing, synthetic stucco exterior finish	50.9 mph	The debris missile perforated completely through the wall assembly.
Source: Wind Science & Engineering Center at Texas Tech University

Table 2: Interior Concrete Wall Wind/Missile Test Results
Wall Type	Test Wall Description	Speed of Debris	Results
Concrete	6-in thick reinforced concrete wall, #4 vertical reinforcing bars at 12 in o.c.; no finishes	109 mph	No cracking, front face scabbing, or back face spalling of concrete observed.
Concrete	Concrete 6-in thick reinforced concrete wall, #4 vertical reinforcing bars at 24 in o.c.; no finishes	102.4 mph	No cracking, front face scabbing, or back face spalling of concrete observed.
ICF block	Block ICF foam forms, 6-in-thick flat concrete wall, #4 vertical reinforcing bars at 12 in o.c.; vinyl siding (tested a second time with similar results)	103.8 mph	Debris penetrated vinyl siding and foam form. No cracking, front face scabbing, or back face spalling of concrete wall observed.
ICF block	Block ICF foam forms, 6-in thick flat concrete wall, #4 vertical reinforcing bars, 24-in o.c.; 3-in brick veneer with ties spaced 12 in each way	99 mph	Debris penetrated and cracked brick veneer. Foam form dented. No cracking, front face scabbing, or back face spalling of concrete wall observed.
ICF panel	Panel ICF foam forms, 4-in-thick flat concrete wall, #4 vertical reinforcing bars at 24 in o.c.; vinyl siding	96.7 mph	Debris penetrated vinyl siding and foam form. No cracking, front face scabbing, or back face spalling of concrete wall observed.
ICF block	Block ICF foam forms, variable thickness "waffle" concrete wall, 6-in maximum thickness, and 2-in minimum thickness; #4 vertical reinforcing bars in each 6-in vertical core at 24 in o.c.; synthetic stucco finish (tested a second time with similar results)	100.2 mph	Debris penetrated synthetic stucco finish, and foam form. Impact of wall [words missing?] at 2-in thick section. No cracking, front face scabbing, or back face spalling of concrete wall observed.
Note: All concrete tested to 3,000 PSI compressive strength, maximum aggregate size 3/4 in, 6-in slump.  Source: Wind Science & Engineering Center at Texas Tech University

Remodeling for Disaster Storm shutters are a simple, inexpensive retrofit that will help minimize wind and rain damage during hurricanes.  In some areas of the country, many contractors today probably have more work in disaster recovery remodeling than in energy efficiency remodeling. What improvements help to prevent disaster?  In hurricane regions, temporary or permanent storm shutters are important. FEMA estimates that storm shutters cost $50-$60 per ft2 of window. A simple plywood cover costs about $10, but will not resist impact nearly as well as storm shutters. KeepSafe glass by Solutia may be another solution to water and wind damage. KeepSafe is an impact-resistant laminated glass formed by bonding two pieces of glass to a hardy polyvinyl butyral (PVB) plastic interlayer that will not shatter and fall out upon impact. Pricing for KeepSafe depends on the window manufacturers. Window replacement costs vary depending on brand, features, and size. FEMA urges planning ahead for window protection--once the hurricane warning has been issued, there probably won't be enough time to purchase materials and install protective measures. Tremors from even minor earthquakes can turn TVs, computers, art, and books into projectiles. Electrical equipment may be damaged beyond repair. Broken glass and heavy books can kill. A few simple adjustments can keep things in place. Anchor bookcases, appliances, and water heaters to the wall so they won't topple. Use strong brackets attached firmly to the structure. Be sure to use screws long enough to reach the studs. During an earthquake, drawers and doors may swing open, spilling their contents. On open shelves, a molding lip, a thin metal or plastic rod, a wood dowel, or even an elastic band across the front of each shelf will help to keep books in place but still let you remove them. Childproof latches, RV latches, barrel bolts, or safety hasps will keep most cabinet doors closed, though a lip, rod, or band across shelves adds protection. RV and childproof latches are best because they actually latch each time the door or drawer closes. In an earthquake, utility lines can snap. Where possible, install flexible connections on gas furnaces, hot water heaters, clothes dryers, and stoves. Don't forget to anchor these items to the structure to prevent their falling. Especially in older homes, make sure the house is properly secured to its foundation, that the foundation is properly braced, and that the roof is firmly attached. These repairs may not be as costly as consumers think. For example, FEMA estimates that to bolt sill plates to the foundation of an 1,800 ft2 house with a perimeter of 180 ft would require a minimum of 30 bolts and cost somewhere between $1,500 and $2,250. In hurricane regions, reinforce garage doors or replace them with reinforced doors. FEMA estimates that reinforcing an existing two-car garage door will cost about $300, and that bracing a roof will cost about $75 per gable end. Also reinforce double-entry doors. Add a heavy-duty dead bolt or replace the existing dead bolt with a stronger one; add a slide bolt at the top and bottom of the inactive door; and replace the existing hinge attachment screws, in both doors and door frame, with longer screws sunk well into the frame. FEMA estimates that this will cost about $100. Of course, the important thing to remember in remodeling is that, if you're ripping into walls and crawling through the crawlspace anyway, you might as well do all that weatherstripping, air sealing, and insulation installation that most every home needs more of for better energy efficiency and improved comfort. See Home Energy's book, No Regrets Remodeling, for details on how not to miss those opportunities for energy-efficient home improvement. Finally, educate your clients on energy efficiency loans and home improvement loans. This will help to overcome any doubts they may have about the cost-effectiveness of this approach.

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