Making design choices on a 10' diameter earth bag
root cellar
project. We have very poor soil percolation and have already prepped a compacted raised pad to build on and will build a hill over the structure. We completed an earthbag root cellar at my neighbors property and I hope to improve this one based on the
experience. The existing structure has an interior diameter of 8' and we used the catenary curve for wall structure. The inherent stability of that style is a proven technology, yet has some drawbacks that I would like to avoid. It yields a sloping wall with excessive height in the center. The compound-curve wall makes storage more difficult and the added height requires more fill for insulation and an overall larger profile to the resulting mound. I would like to do a circular structure, but with vertical walls. If we use earthbags to the level of the door lintel and cap the bags with a
concrete bond beam and build a robust insulated roof attached to the bond beam, I'm hoping to reduce the overall height of the mound while retaining sufficient insulation and earth cover. The structure will be used as a storm
shelter as well, and the interior space
should be more accommodating with the vertical walls. A
local expert on root cellars suggested that I tent the entire structure with a layer of foam board sandwiched in the soil covering. I am considering that option along with internal earthbag buttressing to resist the thrust on the walls. The interior buttresses would take up interior space, but I could use them for shelf supports or as dividers for different zones. I am in an area where 5' frost depth is not unusual.