How Can I Strengthen an Adobe House in a Seismic Area?

http://www.motherearthnews.com/green-homes/adobe-building-earthquake-resistance.aspx

I’ve heard it’s dangerous to build with adobe in seismically active areas. Is this true, and is there anything I can do to reduce the risk?

Yes, any type of unreinforced masonry is dangerous in seismic areas. But almost all types of construction are at risk in these areas, including conventional wood-frame construction. The key is to learn how to mitigate the risk through proper construction techniques, or move to a safer location.

For starters, learn what earthquake zone you are in and the building requirements.

Here are some important considerations and simple steps that can strengthen adobe houses and other types of unreinforced masonry:

  • Single story versus multiple story: Single story houses are safer.
  • Ratio of wall height to wall thickness: The maximum height is 10 times the thickness.
  • Size and spacing of door and window openings: Additional openings and closer spacing increases risk.
  • Weight of roof materials: Lightweight roofs are safer.
  • Length of unbuttressed walls: Longer walls are less stable.
  • Curved versus straight walls: Curved walls are inherently more stable.
  • Properly designed foundation: reinforced concrete foundation
  • Soil type: The best option is to build on solid rock.
  • Also consider stucco mesh applied to both sides of walls and tied together, reinforced bond beam, attachment of wall to bond beam, and roof ties.

Another option is to add steel reinforcement to adobe walls. Adobe Building Systems uses hollow, cement-stabilized adobe blocks reinforced with rebar and grout.

Want to enhance the seismic resistance of your earthen home even more? Consider earthbag construction: For more information see www.EarthbagBuilding.com and Earthbag Building Blog.

— Owen Geiger, Founder and Director of the Geiger Research Institute of Sustainable Building