and have good protection from fabric damage, relying on the strength of the bag fabric for wall strength. CS needs more vertical reinforcement for both shear and out-of-plane strength than CE, or may require a structural skin. Some builders use narrow bags of contained sand as wall infill. Contained gravel (CG) uses fill of any aggregate larger than coarse sand, usually in doubled rice bags, although strong mesh can be used. CG limits dampness transmission from footings. Modular CE is built in grain bags or similar tubes. Walls rely on attachment between barbed wire barbs and/ or added pins between courses. Solid CE is hyperadobe built in some type of knit raschel mesh tube, so that the damp earthen fill solidifies between courses. Bag-fill materials Generally inorganic material is used as filler, but some organic material (such as rice hulls) can be used if a strong matrix like wire mesh reinforces the plaster. Earthen fill may contain 5–50% clay, and can be "reject fines", "road base", "engineered fill", or local subsoil. "Raw" or un-stabilized soils cure as solid units but cannot withstand prolonged soaking. Subsoils with clay mold tightly and attach well to barbed wire prongs and rebar. Soil fill can contain a high proportion of aggregate, as long as it tamps and cures strongly. Crushed bottles, strong rubble, or plastic trash can be used, but high aggregate mixes may interfere with inserting rebar. Sands, stone dust and gravels can survive prolonged flood conditions, but most require special bracing during construction as well as some form of structural skin. Sand fill may be appropriate for several courses to provide a vibration damping building base, but becomes unstable in ordinary bags above in height. Cement, lime or bitumen stabilization can allow clay soil to withstand flooding or allow sands to be used in traditional bags with a non-structural plaster skin. Because earthbag walls are usually thick a large amount of stabilizer is needed. Thermal insulating properties are important for climates that experience temperature extremes. The thermal insulating value of a material is directly related to both the porosity of the material and the thickness of the wall. Crushed volcanic rock, pumice or rice hulls yield higher insulation value than clay or sand. Untreated organic materials that could decay should not be used as part of a structural wall, although they can be used as infill. United Earth Builders has tried a