Stage 4: Bury Berm and Cap

This all happened very fast, as we had a group of local school children coming out again to build and we could not move ahead with the cap layer unless we had a berm to lay it upon. In addition, our usual picture taker happend to be on vacation so I apologize for the lack of good visuals.

In short, 0.5mm plastic was wrapped around the stem wall. Part of the gravel around the bottom layer of bags was dug out so that the plastic would extend below our lowest layer of bags by about 10cm.

The plastic was overlapped about a meter and humbly sealed with duct tape. It was also secured to the top layer of bags in the same manner to prevent it from moving when the gravel was infilled.

Using the back hoe, gravel was infilled around the entire structure, up to around 80cm in height. Dirt was then bermed (by hand and with the backhoe) around this gravel infill to hold it in place so we could add the last 20cm of gravel.

The last 20cm of gravel were packed in by hand. And then the back hoe reinforced the berm with more dirt and then tamped it down with the bucket.

The resulting berm, which can be seen below, was then capped with two rows of very big bags. These bags are much wider than the bags we have been using until this point. They extend out onto the berm about 10cm. These two rows will function as a base for the above ground dome layers, and will effectively seat the entire structure into the earth.

Bury and Berm CompletedBig bag cap layer oneNotice the plastic around the perimeter. Once this first cap layer is finished, the plastic was secured on top of it and permanently affixed by the addition of the second cap layer. 20cm of gravel was also infilled inside the structure to reduce the severity of the drop from the entry to the floor. This is significant as the inner diameter is only 3 meters, which doesn’t leave a lot of real estate for stairs. It should be noted that a larger dwelling intended for living would not need to worry about this problem.

First cap layer completed

When the structure is finished, gravel will be infilled around the perimeter to cover this plastic and protect it from UV degredation and plant intrusion.

Now onto the second cap layer and the installation of the door and window box forms.

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