Green Home Building and Sustainable Architecture

Sustainable architecture is an exciting and important field, with many people reviving traditional methods of building and others creating innovations to established practices. Kelly Hart, webmaster of the popular website, posts text and photos featuring what he discovers from around the world.

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Location: Crestone, Colorado, United States

Kelly Hart has been involved with green building concepts for much of his life. He has also worked in various fields of communication media, including still photography, cinematography, animation, video production and now website development. Kelly has lived in an earthbag/papercrete home that he built and consults about sustainable building design.

August 12, 2008

Building with Unbonded Pumice

Dr. Owen Geiger and I have just found that a book published in 1990 in Germany, Building with Pumice, written by Klaus Grasser and Gernot Minke, describes experiments done in the 1970’s at the Research Laboratory for Experimental Building at Kassel Polytechnic College in Germany that have considerable bearing on the history of earthbag building.

Most of the book is about the physical properties of pumice, how to obtain and process it, and how to make blocks or walls with pumice/cement, but the fifth and final chapter, titled “Building with Unbonded Pumice,” describes how they began to investigate the question of how natural building materials like sand and gravel could be used for building houses without the necessity of using binders. The use of fabric-packed bulk material was found to be a cost-efficient approach. They used pumice to pack in the bags, because it weighs less and has better thermal insulating properties than ordinary sand and gravel. Their first successful experiments were with corbeled dome shapes (an inverted catenary) which was obtained with the aid of a rotating vertical template mounted at the center of the structure.

1978, a prototype house using an earthquake-proof stacked-bag type of construction was built in Guatemala. They used cotton bags soaked in lime-wash to protect the material from rot and insects. When flattened, the bags measured roughly 8 X 10 cm. Vertical bamboo poles placed on both sides of the bags and interconnected with wire loops gave the stacked bags stability. The bamboo rods were fixed to the foundation and to the horizontal tie beam at the top.

Obviously the concept of constructing homes with fabric bags of mineral material predates Nader Khalili’s earliest experiments by many years, and I was certainly not the first to experiment with filling earthbags with pumice! The entire chapter is reproduced as an article at


Anonymous Anonymous said...

I wonder if this is where nadar khalili got his inspiration for earthbag building from.

5:07 AM  
Anonymous Anonymous said...

It is hard to imagine that Nader Khalili did not know about the work of Gernot Minke, a world-renowned professor and author, who was experimenting with these techniques nearly a decade earlier than Nader was!

7:41 AM  
Blogger Samson said...

Hi Kelley. I am looking for plans for a small/tiny house (300-800 sq ft or so) that is self-sufficient, sustainable, affordable and easy to maintain. As America is downsizing older Americans are going to need a place to live. It needs to be simple and easy to build. Communities of small houses could go up as everyone gets together like the old barn rising times. I have always loved the idea of a timber frame house but any tiny plans for this environment would be good. If you don't have anything like this Kelley can you refer me to someone. I am doing a local TV show and would like to start a movement with this kind of housing and feature it on the show. I live in San Luis Obispo and would like this area to be the leading testing grounds with all kinds of new green self-sufficient ideas. Thanks Jeanne

12:28 AM  
Blogger Kelly Hart said...

This comment has been removed by the author.

8:29 AM  
Blogger Kelly Hart said...

Truly self-sufficient housing is rare and difficult to achieve, since this really means that house require no additional inputs for all energy and water use, and can handle waste outputs as well. Small houses are becoming more popular as people discover their benefits in terms of energy efficiency, convenience, cost, and homeyness. I have a page about small homes at that lists lots of resources regarding this.

8:31 AM  
Blogger Kim said...

I agree, it's difficult to be truly independent/self-sufficient. After all, it's what a community is all about and what one person does affects another, no matter how small.

That being said, small houses and learning to be more independent than we are today is always a good idea. Not only does it grow confidence in your own ability to manage in tight times, it also minimizes your expense! Always a plus :)


3:11 AM  

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