Disaster-resistant construction

During a seminar sponsored by the Kenai Peninsula Borough's Project Impact office in November, designers, contractors and other building specialists got a lesson in disaster-resistant construction.

The program covered flood-resistant plans, designing for natural gas appliances, and building with "prescriptive design," a way to lay out a building so all parts work together to resist the forces of nature.

Did You Know?

The Alaska Good Friday earthquake of 1964 had the equivalent destructive power of 944,822,888 tons of TNT, or 73,000 Hiroshima-sized atomic bombs.

-- Information from: U.S.G.S. "The Next Big Earthquake"

by Peter Haeussler

Flood-resistant designs

Christy Miller, a planner with the Flood Insurance Program of the state Division of Municipal and Regional Assistance, presented the flood-resistant design workshop. In it, she warned against building in the 100-year flood plain. That's the area where there is a 1 percent chance in any given year that there will be a flood.

While that does not sound like very bad odds, remember that a 100-year flood is the worst-case scenario and brings with it a lot of disaster and worry.

"I've seen houses along a river during a 100-year flood that weren't wet yet, but as soon as a boat went by, the wake pushed water into them," she said.

Building the right kind of foundation is extremely important in making a structure flood resistant. Building on stilts or pilings and having openings in foundations and ground level walls are good ways to keep the pressure of the flood waters from moving a house off its foundation.

Miller warned that new Federal Emergency Management Agency guidelines will require new homes to fill crawl spaces even with the ground level. She said she is unsure how that will affect existing buildings.

"If I lived on the Kenai River flood plain, I'd buy flood insurance even over fire insurance," she said.

A key point to remember if building in a flood plain on the peninsula, Miller said, is that national flood insurance is only available outside the cities of Kenai, Soldotna and Homer. Since those cities have their own planning powers, they were left out when the borough joined the program.

For more information on flood mitigation, Miller can be reached at 269-4567 or via e-mail at:

Christy_miller@dced.state.ak.us.

Natural gas

Two officials from Enstar Natural Gas Company gave an overview of using natural gas in the home. Charles Pierce, Southern Division manager in Soldotna, and Ed Oxborough, the service supervisor from Anchorage, reminded builders that for appliances such as boilers, clothes dryers and heaters, good ventilation is important to provide a lot of combustion air.

When burned at 100 percent efficiency, Pierce said, natural gas produces only carbon dioxide, a relatively harmless gas. But in a tight house without much ventilation, combustion efficiency declines and the dangerous gas carbon monoxide is produced. That's the same gas that killed four members of a Nikiski family in December of 1997.

"Too tight of homes sometimes don't provide enough combustion air," Oxborough said. "Remember, you're putting something in there that wants to breathe, so you've got to give it enough air."

Contractors were also reminded that if they put any gas-fired appliances in a garage where the ignition spark or flame may come in contact with vapors from automobile gasoline, to place them at least 18 inches above the floor to avoid explosions.

"The (uniform plumbing) code is designed to take into account all of this," Pierce said. "It's sometimes an inconvenience, but if you go through these steps, it will make for a safer and cleaner system."

To learn more about natural gas safety, call Pierce at 262-9334.

Prescriptive design

The last segment of the seminar was a description of what is known as "prescriptive design." James Gray, an engineer with the Anchorage building safety division, put the group through a workbook on the building philosophy.

"If prescriptive principles are used, the building design will take care of wind and earthquake design concerns," Gray said.

He said that by following prescriptive design principles a builder can avoid expensive engineering to make sure a home is designed properly.

"Under traditional design, unless you had an engineering background, you couldn't (design it yourself)," he said. "Under prescriptive design, anybody can do it."

The benefits of prescriptive design depend on putting clear span walls of a minimum length from foundation to roof, putting braced walls in certain places and limiting unusual building shapes.

Gray said by transferring the load from the plane of the roof directly to the foundation, a building is much more resistant to the forces of wind and earthquake that may otherwise tend to damage a home.

"However, just because a structure is built to code or prescriptive design, doesn't mean it will stand up to the big earthquake," he said. "What we're looking for is a basic level of design safety that will allow people to get out alive."

For more information about prescriptive design, Gray can be reached at 343-8384 or GrayJD@ci.anchorage.ak.us.