Cob foundation options

The "boots" are one of the two most critical parts of any cob home, right? Which design and materials are right for my home? I intend to build in Nicaragua, a tropical country with a distinct dry and rainy season. That means significant rainfall at times. Drainage will likely be a key element in my design. Furthermore, it is a seismically active area of the world. I don't believe the standard rubble trench/stone plinth foundation alone will be adequate protection from earthquake damage. If at all possible I want to avoid the use of concrete, due to environmental concerns and the hydrophilic properites of concrete. I've come to the conclusion that gravel filled earthbags on a rubble/trench foundation might be the best option in my case. This foundation can be strengthened by the use of barbed wire and rebar stakes. I would greatly appreciate any opinions/comments with regards to the effectiveness of such a foundation. Any suggestions would also be welcomed. Thank you for your attention. I'm looking forward to reading a response.

Jacob Moore : A very late welcome to Permies, Often we find it easier to reach-out to people who seem local, in this case, if you hadn't mentioned Nicaragua, I expect
that you would have had many responses, Most people are assuming that someone local to you will pick up the slack ! Unfortunately we are also under represented by
Spanish speaking members !

I hope that you have been following recent posts here in the Cob Forums, Foundations and Cob boots being two of the most important, I live in the northeast corner of
the United States, and here all memory of cobs and cob buildings have been lost ! You know more now than I did 6 months ago, Having played with cob in Rocket Mass
Heaters And Cob ovens, has diven me to do parallel research to where you are now ! I can strongly recommend two books Ianto Evans' et al 'The Hand-Sculpted House'
and Michael Smith's The Cobbers' Companion these books are both available Used through Amazon books and my favorite Alibris books.

The best way to generate hits on this thread is to pick one or more very specific questions, at no time at all we will generate a lot of hits and some thing to Catalog !

For the Good of the Craft ! Be safe, keep warm ! As always, comments and questions are solicited and are Welcome ! PYRO - LOGICAL BIG AL

Jacob,

How strong are the earthquakes in your part of Nicaragua? I believe that most cob houses stack up to the earthquake tests very well, as far as safety is concerned, they should not fall down or collapse. I believe the problem with earthquakes and rubble trench foundations is if the shake is strong enough, it will shift your entire home as one piece off of its trench footprint. Earthbags seem like a good idea, I have little experience with them. I have heard of people using a cement/lime bond beam all the way around the structure (including under the door) in which they set in their first course of 'urbanite' or stone foundation while still wet. It is not a popular, or necessarily environmental thing to use cement, but if a small layer keeps your home standing or centuries, it may end up being more green in a sense. Have you seen 'El Barro, las Manos, la Casa'? It was filmed in El Bolson, Argentina and is probably the best up-to-date video there is on natural building. They go through history, materials, and methods. There are trailers online, and if you search hard enough you maybe able to find the whole thing streaming somewhere, but I would highly recommend finding and watching it. In the video they also use a method somewhere between a corbel and slipstraw to make a long clay/straw rope that acts as the bond beam atop of an adobe wall which they claim is required for their natural building code. Hope this helps.

- Jim

Hi Jim, thanks for responding. Earthquakes can be strong in Nicaragua as it's located along the ring of fire. I watched the movie El Barro, Las Manos, La Casa and found it very inspirational. Also, I've decided to build an earthbag house/shed and will start the project this May. As for the foundation, I'll use a rubble trench beginning a course of rubble filled bags below the ground line and continuing the next couple of rows up with the same rubble filled bags. I think the earthbag construction is going to be much more simple and much less time-consuming for the main walls. I've also found a group in Nicaragua working with natural materials Casa De Tierra and they've been an invaluable source of information.