Most earthbag builders use concrete bond beams on vertical wall structures. That’s the best choice, especially in seismic or high wind areas. But what if you’re not in a seismic or high wind area? If money is tight, time is short and you’re more of a carpenter than a concrete worker then consider using a low cost 2”x4” ladder bond beam. This is for rectilinear designs, obviously. And note, this may not meet code in your area, so check with local building officials beforehand or move to where codes are virtually non-existent.
Notes:
– Build on the ground in sections and lift into position.
– Space cross ties (the short boards that are perpendicular to the long boards) 24” apart so they sit next to the trusses or rafters. This adds additional strength at no extra cost.
– Reinforce corners and joints with plywood and construction adhesive, and metal straps.
– Spike bond beam to earthbags with rebar about every 2’-3’.
– Save more money by using rough sawn lumber from a local mill (or from your own bandsaw mill).
– Insulate the bond beam in cold climates.
– Placement of trusses or rafters is not shown because too much detail clutters the drawing and takes too much time. Let’s assume they bear on the left side of the drawing. That means the cross ties on the right side should be inset about 1-1/2” from the outer edge if you’re using flat bottom trusses and/or gable trusses.
Moisture barrier not shown. I like to add some plastic sheeting (6 mil poly) along the top of the wall that drapes down about 6″. Build the bond beam on top of the plastic.