Earthen walls do well in white areas of BSI's map

Minimal Strength

If quake forces are <0.25 g or less, earthen huts protected from water last hundreds of years. They moderate humidity and temperature swings.

Earth techniques include traditional adobe, puddled adobe, cob, rammed earth and compressed blocks and plastered earthbag.

Basics:

More wall than window

Water-resistant footing and moisture break

Walls thick enough for the height

Stiffen long walls with buttresses

Connect walls to lintels, bond beam

Resilient earthbag for low risk (light gray on BSI's map)

Limited Strength

If quake forces are 0.25- 0.6 g, build with soil at least 1,8 MPa (190 psi) strength. Use field tests to check.

Interconnect footings and walls strongly. Keep stub walls less than 1.2 m (4') long. Space intersecting walls or buttresses every 3- 6 m (10- 20'). Check bracing for risk and details.

Rammed and adobe construction details are included in free versions of NZS 4299 online. Check newer 4299:2020 for CEB details.

Build conventional earthbag with strong (2,1 MPa/ 300 psi) soils. Use some splices linking inserted rebars.

Free Low-Cement CE Construction pdf

Stronger for medium- high seismic risk (dark gray/ black on BSI's map)

Moderate or High Strength

Brittle earthen walls of adobe, CEB, or rammed need rebar and RC footings.

More flexible walls may use gravel bag with wire binding like cob (in cool regions) and reinforced ICEB.

Earthbag's high ductility needs less steel than other walls. Use spot corner reinforced concrete (RC) footings with gravel bag up to 1 g risk.

Free Standard Grade CE Construction pdf

Above 1 g use RC strip footings confining gravel.

Free High Strength CE pdf