Newbie to Permies.com here, so please excuse me if I did anything incorrect with this post. I searched around first, but could not find anything already written that addressed this question.
I'm building a 14 foot diameter earthbag corbel dome in the southern New Mexico desert. Only the first few rows/layers have been put down so far. On the most recent row/layer, I temporarily moved one of the bags inward (toward the center of the circle) by about 2 inches to see how the bags will react when I begin corbelling. As I suspected, the overhanging part of the bag was drooping/sagging.
So, my question is this:
Is sagging/drooping a normal and acceptable part of the corbel dome, or is there something else that I should be doing to prevent sagging/drooping?
I'm replying here bc there is no 'post reply' button showing for some reason. Thanks for your response. Actually, the there is no sagging in the dampened and tamped bags themselves. The sagging is only happening on the overhanging 2 inches (where there is nothing but air underneath the overhang) when I attempt to shrink the circle to create the corbel. That is the part I am curious about.
From what I have read/seen you might not have enough material in the bag, and if the material is moistened then after tamping the layer down they should each be pressing equally towards the middle and hold each other up, and they will dry into a really hard material that shouldn't sag at all.
I'm not quite a lumberjack, but that's OK, I sleep all night and I dream all day; I'll coppice trees, I'll grow my food, and compost poo and pee! With a well and off-grid solar, it's a permies life for me! https://www.youtube.com/watch?v=FshU58nI0Ts
I haven't done earthbag building as such, but simply from my experience with materials, I expect the sagging you see is normal. I think you will need to tamp the corbel bags horizontally as well as vertically if you want the inner face solidified. It doesn't matter if the bags sag a bit on the inner face as long as they stabilize in position.
The "Post Reply" button should be on the bottom left under the latest post, if you have a standard computer window view. If you have a phone or tablet, it may be different and I can't say where elements will be.