Mike, in Texas, has been asking some interesting questions about wrapping a post and beam frame with tubes of rice hulls. He thinks this is probably the fastest way to build an earthbag house. He may very well be right. Conversations and blog posts like this one are my favorite. Here’s part of my email reply to Mike.
Previously I reported on the rice hull house in Thailand that was a success. The owner has agreed to write a follow-up report soon that we’ll publish here when available. So we know rice hulls will work under certain conditions. The main issue is keeping the hulls dry.
Here are some suggestions for speeding construction. Note how all the machines could be rented so you don’t have to invest in a lot of expensive equipment. You could rent a cellulose machine (blower) and blow rice hulls through a hose into earthbag tubes. (Tubes are faster than bags.) This would take about one day like you said. But you have to figure out how to stabilize the tubes (hold them in a vertical plane and prevent from shifting around). I would put 4×4 posts or round poles about 3′-4′ apart to align with windows, doors and corners. A posthole auger would make quick work of digging holes. Build the roof before proceeding. Factory made trusses are fast and efficient. Now you’re ready to fill the tubes. Put the tubes on the outside of the posts and attach to backside of posts with baling twine. Put baling twine between tubes for later attachment of plaster mesh. Spray the walls with plaster using a mortar sprayer. Use wide roof overhangs and/or wrap-around porches so the rice hulls never get wet and so you can use earth plaster to save money. First 2-3 courses are gravel bags/tubes to prevent moisture problems. In Texas you could make the rubble trench flush with the ground and use just two courses of gravel bags/tubes. Post and beam with factory trusses and engineer’s stamp would enable bank financing, contractor sales, building permits and insurance if necessary.
Earthbag is super simple. But for those just starting out, my earthbag building book and DVD are now available. Everything is explained in great detail.
Below is a work schedule based on a modest sized home with experienced crew and mechanized system (cement mixer, truck to bring the sand and cement right where it’s needed, post hole auger, insulation blower):
Day 1: Dig trench and post holes, rough plumbing, fill trench with gravel, set posts in concrete
Day 2: Set beam, fill 2-3 courses of gravel bags (back truckload of gravel right next to work area)
Day 3: Set trusses, sheath roof, install metal roofing
Day 4:, Fill tubes with rice hulls
Day 5: Minor carpentry (windows, doors, interior walls), run electrical, attach mesh
Day 6, 7, 8: Spray plaster (move mixer and materials right where it’s needed)
Day 9: Earth floor (see blog post on 11 different earth floor methods)
Day 10: Ceiling, finish electrical and plumbing