The importance of using trained engineers, architects and supervisors can’t be emphasized enough. Due to a lack of trained builders, a few dangerous earthbag projects have been built in Nepal by what I call ‘cowboy builders’ – those with little or no training or building experience. We heard of a school in Mazel in Ghorka that was described as “the worst earthbag building in Nepal”. It has bamboo pins eaten by insects instead of steel rebar, two large 8’x8’ windows set 3’ apart, and dry soil fill consisting of 100% silt which has no binding strength. Proper earthbags are made with moist subsoil containing clay and aggregates, and then tamped solid to create ‘rammed earth in bags’.
Another dangerous project, a school in Dhading, made the news when the concrete vault on top of earthbag walls collapsed, injuring several workers inside. The earthbag walls remained intact, only the concrete vault failed. Again, the cowboy builder had no relevant training other than taking a workshop in the US. The builder was warned at least two times by professional builders and engineers that the structure would collapse, and exactly how and why it would collapse. Unfortunately the builder ignored their advice. He fled the country shortly afterwards. First Steps Himalaya has since been contracted to bulldoze the structure and build a new earthbag school to proper standards.
Good Earth Nepal offers free earthbag training to locals in Kathmandu. The same training is available to foreigners for a very small fee. Please, please. Get good training and build safely.
The amount of skill, concrete quality, and reinforcement for a monolithic roof pour, especially to the seismic structural requirements, isn’t a very diy thing. Yes monolithic concrete domes are very reinforced shotcrete and very durable. But diy, I vote ferrocement, especially in seismic areas
They could have gotten closer to catenary and less roman, in order to keep forces more compressive and less tensile if there was not enough quality reinforcement or pour. A steeper pitched arch would have produced less lateral thrust.
Sucks that this person ignored engineering.
Ok I’m done but want more info
Too bad they weren’t cowboy ferrocementers. Though I imagine quality mesh may be difficult to obtain there
Mesh is available because almost everything is geared toward concrete construction.
Was it unbuttressed lateral thrust exerted from the outermost barrel vaults?
Also, no real bond beam.
The barrel vault ends (arched sides) need shear resistance, either thickened reinforced edges, or better substantial shear end walls. Squeezing in EB after the fact doesn’t count. Laying up quality tamped bag wall before roof pour, say right next to a form hoop can achieve the correct shape without being in the way.
Straight tall vertical unbuttressed Retaining wall looks like it’ll fail soon with hydrostatic soil pressure.
I was told the temporary shoring was removed after just 3 days. No wonder it collapsed. This probably happened because of lack of training and communication between languages. The organizers were training locals to do the work on their own. They thought the locals understood the process by the time they got to this vault.
“The builder was warned at least two times by professional builders and engineers that the structure would collapse, and exactly how and why it would collapse.”
Any more details?
See comments above. The shoring was taken out way too soon and it promptly collapsed.
How much would you like to bet that these guys get all the media attention?
They did get some attention, but as far as I know cowboy builders get less attention than successful projects.
One of the trainers on the project wants to tell his side of the story. Stay tuned.
good advise, Owen.