Hurricanes offer similar lessons

Lessons learned from Hurricane Sandy about how best to limit damage to buildings closely track those of Hurricane Katrina, a federal engineer said Monday. Elevating generators and pumps is a good idea but enclosing elevated foundations that might be hit by waves or wave-borne debris can cause problems.

John Ingargiola, a structural engineer for the Federal Emergency Management Agency, said the final report on Sandy is scheduled in the fall. But FEMA is releasing seven advisories for rebuilding and minimizing future flood damage for new construction, plus a fact sheet about cleaning and drying buildings.

Ingargiola’s comments came during an early workshop at the National Hurricane Conference in New Orleans.

Photographs he showed from Sandy’s destruction looked very much like those after hurricanes Katrina and Rita in 2005: Houses washed from their slabs or collapsed into their foundations and critical equipment such as generators or switches flooded on ground floors or in basements.

“I think, together as a community, we need to think of ways to collaborate and get the message out” about storm-resistant construction, Ingargiola said.

After the session, he said Katrina’s lessons were similar to those of Florida after Hurricane Andrew in 1992.

Florida had a mishmash of local construction standards before Andrew destroyed neighborhoods south of Miami but imposed statewide regulations afterward and did much better in the storms of 2004-05, he said.

Similarly, buildings in areas slammed by Katrina were generally in good shape after Hurricane Isaac last year, he said.

People at the session also learned that while elevating homes on piers reduces flood danger, it requires extra work to protect the slab foundations lifted out of the ground.

Inspectors saw numerous houses that looked fine but had cracked slabs because they were raised without enough permanent reinforcement, said Erin Ashley of URS Group Inc., a contractor that did damage estimates after Hurricane Isaac struck Louisiana last August.

She handed out CDs of the final report about Isaac.

Among its recommendations:

  • Outside stairs to a raised house should have openings between risers to let water through. If that’s not possible, the risers should parallel the likely direction of waves.
  • If the area between the first floor and the ground is enclosed, use materials that resist flood damage and design walls to break away in a flood.
  • If a homeowner plans enclosed parking under a raised building, make the garage ceiling a firewall.

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