Seismic Issues
Pictures

Chimneys that Survived
Some new - some old and well maintained

New, built to code
Courtesy of BIA and TMS
Disaster Investigation Team

Old, fireplace
Courtesy of BIA and TMS
Disaster Investigation Team

Well built & maintained
Courtesy of BIA and TMS
Disaster Investigation Team

New & braced
Courtesy of BIA and TMS
Disaster Investigation Team

New, built to code
Courtesy of BIA and TMS
Disaster Investigation Team

Old, maintained
Courtesy of Jim Buckley

Old, fireplace
Courtesy of Jim Buckley

Retrofitted & braced
Courtesy of Jim Buckley

Old, fireplace
Courtesy of Jim Buckley

Old, fireplace
Courtesy of Jim Buckley

Old, maintained
Courtesy of Jim Buckley
Chimneys that Didn't
All old un-reinforced chimneys

Old & tall
not reinforced or braced
Courtesy of FEMA

Pre-existing damage
Gas flue condensation
Courtesy of Jim Buckley

Pre-existing damage
Gas flue condensation
Courtesy of BIA and TMS
Disaster Investigation Team

Tall, no reinforcing
not strapped
Hope furnace not blocked
Courtesy of BIA and TMS
Disaster Investigation Team

Not reinforced
House knocked it down?
Courtesy of BIA and TMS
Disaster Investigation Team

Not maintained
Courtesy of BIA and TMS
Disaster Investigation Team
Conclusions
No masonry chimneys that were built to modern codes, reinforced and strapping to the house failed.

Moreover many old chimneys - even tall chimneys - did not fail. In the worst areas of Olympia near the Capitol, where nearly all of the chimneys were old and un-reinforced, far less than half of the chimneys were damaged by the Nisqually Quake.

The chimneys that did fail were, by in large, already in poor condition and in need of ordinary maintenance. Several of the chimneys that failed were lined with small metal flues indicating that a gas furnace had been vented into the chimney, and that probably the chimney had been damaged by acid flue gas condensation before the lining was installed. One chimney in particular had grass and moss growing out of the mortar joints. Chimneys that served fireplaces and not furnaces generally faired better.

Recommendations
For old chimneys that might not have been damaged this time the following preventative measures might be considered:
  • Repair and maintain chimney crowns to keep water out of the masonry. Cover the chimney with a rain cap. Make sure the crown has a drip edge.

  • If the chimney is relined to vent a condensing gas furnace, re-inforce the chimney by placing re-inforcing steel and grout around the small gas flue liner within the old masonry flue and repair any damage to the exterior masonry and crown that already may have been caused by venting the gas appliance into the too large masonry flue.

  • Strap the chimney to the roof and brace all chimneys over four feet above the roof.

  • While it's more expensive, consider seismically retrofitting the chimney in the ways recommended for rebuilding damaged chimneys under Rebuild, Repair, Restore.

Chimney Seismic Index
Prepared for FEMA by Jim Buckley