How to Build an Earthbag Dome

Step 15 Living Roof

The easiest method of finishing the dome is plaster. We live in a rainy climate where a plastered dome might leak. Plus, we wanted a beautiful plant covered dome in our backyard. Living roofs require a lot of regular maintenance just like gardening, so think long and hard before going this route. Without regular watering, weeding and fertilizer the living roof will turn into a giant weed patch, die or maybe even erode away. We’ve worked hard to establish really healthy grass, as you can see in the photo.

The main steps for the living roof include adding two or three layers of 6 mil plastic sheeting (“black poly”). I put one layer directly against the dome and back side of the buttresses. Then I backfilled with earth (more road base) about half way up and added another layer of plastic. I added a third layer of plastic on the top of the dome where the risk of water penetration is greatest. Work carefully and try not to puncture the plastic. Gradually add soil on top of the plastic starting at the bottom and working up. Compact it slightly as you go. I used ‘field dirt’ – soil from rice fields for this step. It has enough clay to stay in place, but still enable grass to grow. Add drought resistant sod once the dome is covered in a layer of soil. Some pieces of sod require bamboo pins to keep from slipping. Time the project so the sod gets started during the rainy season. We have a lawn sprinkler on top of the dome and water it whenever it gets dry.

Comments

[danzo321]

If you had included capped 2-liter soda bottles, squashing the dirtbags against them, you'd have skylights. Wouldn't work with the grass layer, but what other toppings have you considered?

[Oshgood]

Beautiful instructable! Beautiful process! Beautiful results!
Thank you for sharing this... It´s beautiful! I am going to build my own house soon and this method looks very interesting.

Love frome chile!

Eugenio

[mgalyean]

How easy is it to repair a leak if one develops compared to a shed built normally? I guess I'm getting at how "maintainable" is the structure compared to something which has a structure more exposed to maintenance and less "woven" and "integrated" to the extent that it can be hard to replace/repair a section (perhaps damaged by rodents) without risking structural failure.

Be that as it may, I'm thinking an alternate construction technique that might be quite a bit less labor intensive would be to create a large compacted mound of the correct dirt type using a front loader, then progressively hollow it out while reinforcing using standard tunneling/mining techniques, then finish up with a layer of sprayed in rebar'd concrete on the interior if so desired. If a layer of gravel could somehow be engineered between the concrete and the dirt you'd get nice drainage to the periphery and leaks would be minimized. I just can't help thinking about all the plastic for the dirt bags and the 6 mil for preventing leaks and how it might be avoided. Gravel drains nicely generally.

[Owen Geiger]

You're describing ferrocement. That's a good way to build, although you'll still have to be careful to waterproof everything carefully. You don't need to make an earth mound. Just form the rebar in the desired shape and cover with at least 1-2 layers of plaster mesh. You can get the details on the Internet for free.

You can also combine earthbags with ferrocement to insulate the building. I've been describing my ideas on how to do this on our Earthbag Building Blog: http://earthbagbuilding.wordpress.com/

You can fill the bags with various types of insulation. Or you can fill bags or tubes with geopolymer. The bags or tubes are stacked next to the ferrocement frame and tied to it. The geopolymer can be lightweight and insulating. http://earthbagbuilding.wordpress.com/2011/09/23/lightweight-insulating-geopolymer-earthbags-part-3/

[Bicyclette]

I can only hope that I will be able to do this. Bravo to you sir!

[Owen Geiger]

Thank you very much. Hope it works out okay for you.