Old Cob Houses in New Zealand

Cob Cottage in Marlborough (click to enlarge)

Paterson’s accommodation house at Hakataremea was built in 1872.

Cliff, one of our readers, sent me these photos of old cob houses in New Zealand. They look really nice, especially considering their age. I knew New Zealand and Australia have a long history of building with earth, but I didn’t realize how well the buildings are holding up and how beautiful they are.

The Marlborough Cob Cottage is “a good example of how early Marlburians constructed dwellings in a region without a close supply of timber. ‘Cob’ is a building material made from a mix of earth and tussock grass. Cob Cottage is located on State Highway 1 in Riverlands on the outskirts of Blenheim, and boasts being the most visited historic home in Marlborough. In the early 1900s it was used as Riverlands School. When you visit Cob Cottage you can see photos and stories from those early days.”

From the Flickr site: “An old 19th century historic cob cottage, restored and open to the public, on State Highway 1. A plaque provides a message: “This cob house built in the early 1860s was restored from January 1961 to November 1965 by the Marlborough Historical Society Inc.”

“Paterson’s accommodation house at Hakataremea was built in 1872. It has a shingle roof and is built from cob, a building material made of dried mud and straw. This had the advantage of being a good insulator, warm in winter and cool in summer.” [Actually, cob is thermal mass, not insulation, and will get cold if the temperature drops low enough. Same as earthbag.]

Image source: Cob Cottage in Marlborough
Flickr
Image source: South Canterbury Places

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All the Best Earthbag Content

For several years, Kelly and I have been filtering all the best earthbag content from the Web, writing extensively on all aspects of earthbag building and organizing the information for readers. There’s now an enormous amount of information available – so much that it’s difficult to keep up with everything. That’s one reason why our sites are helpful. We gather the best information so you don’t have to spend endless hours looking for it, wasting time clicking through low quality sites, blurry videos, etc. No one else has anything close to this amount of content. Below are just a few links from EarthbagBuilding.com (the mothership) and our Earthbag Building Blog. Also note how we strive to keep all these pages up to date so readers aren’t faced with a bunch of broken links. (And it’s free.)

Earthbag Projects and Pictures
Earthbag Videos
Earthbag Articles
Earthbag Testing
Earthbag Blogs (recently updated and expanded to include earthbag blogs in Spanish)

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Top 10 Most Popular Earthbag Blog Posts

Instructable: How to Build an Earthbag Dome by Owen Geiger

Every year we publish the most popular blog posts for the last 12 months. We’ll do that again in November on our 4th anniversary. Our goal here is to look at the most popular blog posts since we’ve started – the Best of the Bestest. Think of them as hidden gems unless you’ve read all 756 blog posts. (And if you have read them all, then you can start reading the info on our mothership at EarthbagBuilding.com. It’s all free. Enjoy.)

1. Counties with Few or No Building Codes
2. Bullet Resistance of Compressed Earth
3. Low-cost Multipurpose Minibuilding Made With Earthbags (This is my earthbag dome that almost went viral last year and got republished on dozens of blogs… see photo above.) Click here to read the free Step-by-Step How to Build an Earthbag Dome Instructable at Instructables.com.
4. Creating Earthbag House Models
5. Earthquake-resistant Earthbag Houses
6. Earthbag Rootcellar
7. Cost of Earthbag Houses
8. $2,000 Earthbag House
9. Earthbag Survival Shelter
10. Using Earthbags as Ceiling Insulation

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Summary of Earthbag Facts

Let’s take a brief respite from castle plans, shall we? Our website traffic has hit another major spike and so I’ll take this opportunity to summarize some key facts about earthbag building.

A few quick facts:
– Successful completion of an earthbag/strawbale shake table test in Nevada applied forces that surpassed that of the Northridge quake in California.
– Seismic tests in California showed zero deflection on earthbag domes with forces that maxed out the testing equipment.
– Engineer and code approved earthbag designs are now available for seismic and non-seismic areas through Precision Structural Engineering, Inc. This had been a major barrier in the past, and we’re glad to see this service on offer.
– A master’s degree thesis showed earthbag walls have 10 times the bearing capacity of stud framed walls.
– Sand bags are the material of choice for storing ammunition in war zones due to their ability to absorb blasts (if they’re strong enough for this, they’re definitely strong enough for housing).
– Around a dozen earthbag projects are taking off in Haiti. Some of have been completed and the groups involved have decided to build more earthbag structures.
– Earthbag is comparable to rammed earth, which can last for thousands of years. See Ancient Rammed Earth Structures.
– Earthbag consists of compacted earth, which has now been shown to be resistant to 50 caliber bullets.
– Compressed earth walls withstood impact testing from a black powder cannon that’s comparable to forces from F5 tornadoes.
– There are various ways of stabilizing earthbags and/or filling lower courses with gravel to make them extremely resistant to water damage, including floods.
– For cold climates, bags can be filled with insulation or earthbags can be covered with a layer of insulation.
– A Federal Highway Administration report estimates the half life of polypropylene bags (sand bags) may exceed 500 years in benign environments.
– Earthbag is faster and more efficient than building with adobe, cob, rammed tires and rammed earth.
– Building with sand bags is around 250 years old if you include the original burlap structures built by militaries.
– Countless millions of poly sand bags are used every year to hold back floodwaters because they’re simple to use and effective.
– An earthbag wall passed a recent wind test with out-of-plane dynamic pressures up to 30 psf and quasi-static pressure up to 60 psf.

This list barely scratches the surface as far as identifying all the benefits of earthbag building. There are now over 730 blog posts available on every aspect of building with bags — foundations, plastering, domes, greenhouses, rootcellars, you name it, it’s here. Every topic can be searched from the search engine near the top of the page. You can also search this blog and our main site (which is by far the largest repository of all things related to earthbags) with our new search engine at EarthbagBuilding.com.

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Get the Basics Right

Make sure you get the basics right so your earthbag home is safe, sound and durable. As obvious as this seems, the most fundamental earthbag building principles sometimes get lost in the forest of information. That was one reason for writing the Earthbag Building Guide – to focus on the most important steps and demonstrate the best techniques in the right order of construction to avoid mistakes. A $20 investment in this book can easily save hundreds of dollars or more in wasted time and effort. (Same is true with just about any subject – knowledge is power.)

Key earthbag principles:
– Earthbags are not just bags of dirt or sand. Proper earthbags have enough clay in the soil to bind the aggregates together into a solid block.
– Use moist soil, not loose, dry soil.
– Earthbags are tamped solid, much like rammed earth. Once dry, they are similar to giant bricks.
– Avoid slumping corners by pre-tamping the soil (this is explained in my book)
– Overlap bags in a running bond, including at corners or use tubes
– Use barbed wire between courses for tensile strength and to prevent slippage
– Build straight, plumb and level (for rectilinear structures)
– Build uniform, smooth curves if building in the round
– Protect walls with a good foundation and a good roof with adequate roof overhang
– Raise the building site so water flows away from the building.
– Add reinforcing where necessary, especially on long, straight walls and at door and window openings
– Protect the bags from ultraviolet (UV) damage if your project will take more than a few weeks

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Earthbag Building Facebook Page

I got the following email a few minutes ago. Luke just won himself a free copy of my upcoming Earthbag Building Video. Thanks, Luke!

“With great pleasure, I just wanted to let you know a Facebook page has been created for fans of your blog. The name of the page is, “Earthbag Building Blog Fan Page.” It took a few days, and 25 people to ‘like’ it before we could get an official link, but now we’ve got it, which is; facebook.com/earthbagbuilding. The Facebook page will follow your blog and other activity by your other websites, as well as questions and answers can be supported by the Facebook community. I hope that it will also serve another function, when it gains more attention, to make announcements about local or abroad earthbag building workshops.

It’s an honor to be able to do this.”
Luke

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How to Find Answers about Earthbag Building

Are you spending lots of time searching for earthbag information? Using the search engines on this blog and at EarthbagBuilding.com will make the job a lot easier. You’ll have hundreds of the best blog posts and articles at your fingertips. Virtually every topic you can think of has already been examined in detail. This blog, for instance, currently has 661 blog posts and over 2,700 comments. The Frequently Asked Questions page at EarthbagBuilding.com answers hundreds of the most common questions.

EarthbagBuilding.com – our main site that ‘warehouses’ everything on the topic – makes it easy to do in-depth searches on all things related to earthbag construction.
• Browse by category (Resources, Articles, Testing, Projects, Videos, etc.).
• Or search our sites with the built-in search engines. You can also search virtually every article and website about earthbag building on the Internet using the same search engine at EarthbagBuilding.com.

I say this so we can cut back on answering repetitive general enquiries and questions in the Comments section. We’ve answered many thousands of questions so far, but as our sites have grown, so has demand on our time. One reason for writing the Earthbag Building Guide was to clarify the best ways to do things and hopefully eliminate many of the general/repetitive questions. So please utilize these resources we’ve created so we can use our time more efficiently.

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Earthbag Building Guide Acknowledgements

The peer review process for this book has included input from other earthbag builders. I would like to thank all those who participated in our Earthbag Building 2.0 contest and others who made contributions. Gathering the best new ideas from the best builders has helped make this a better book. Contributors include Dr. Bill Taha, S.E. of Precision Structural Engineering, Inc.; Fernando Soneghet Pacheco, engineer and developer of Hyperadobe at EcoOca – Brazil; Joseph F. Kennedy, editor “The Art of Natural Building” and “Building Without Borders”; Kelly Hart, owner/developer GreenHomeBuilding.com, and co-author EarthbagBuilding.com and Earthbag Building Blog; Jeff Bousquet of Holistic Healing Homes; Julien L. Balmer of Phangan Earthworks; Scott Howard of Earthen Hand Natural Building, Owen Ingley of Plenitud Iniciativas; Alex Klein of “The Life and Times of a Renaissance Ronin”; Paulina Wojciechowska of Earth Hands and Houses; Sunny Cai, Ph.D./Professor at Renmin University of China; Tim Merritt of Emergency Shelter Kit; Jesse Loving; Dada Krpasundarananda; Troy Griepentrog; Dr. Johnny Anderton of Eternally Solar / EarthBagBuild.com; Tim Hall, Hawaii’s Green Guru and other generous and creative people and organizations.

The bottom line is I don’t believe any one person could write such a thorough coverage of earthbag building that includes all the new advances of the last year or two. So again I want to say thank you to all those who contributed to this book.

The Earthbag Building Guide is now available for $20 as a PDF download. The ebook is available for free with all new house plan orders through Earthbag House Plans and DreamGreenHomes.com.

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Earthbag Building Guide Table of Contents 2

Earthbag Building Guide Table of Contents 2

More book reviews:
“This book is very useful for anyone interested in working with earthbags…even those who have experience, since there are many new and innovative concepts presented. It embraces all aspects of safely constructing vertical earthbag walls, discusses ways to insulate and plaster them, and talks about roof options and other details. It even introduces the revolutionary Hyperadobe concept from Brazil! This is a powerful resource.” Kelly Hart, owner/developer GreenHomeBuilding.com

“This book will expand our thinking about how we build and where we live. The point-by-point instructions are a wonderful quick reference, and the detailed explanations explain every aspect of each step from foundation to roof.” Troy Griepentrog, editor Mother Earth News Magazine

The ebook is available for free with all new house plan orders through Earthbag House Plans and DreamGreenHomes.com.

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Earthbag Building Guide Table of Contents 1

Earthbag Building Guide Table of Contents 1 (click to enlarge)

More book reviews:

“I have built with earthbags for over twenty years, having helped develop the concept with Nader Khalili in the early 1990’s. Of all the texts on earthbag building that exist (including mine), I have to say that Owen Geiger’s Earthbag Building Guide is by far the most thorough, detailed and technically useful book on the subject yet to emerge. I will be referring to it often in my own projects and look forward with keen interest to forthcoming titles from this talented researcher.” Joseph F. Kennedy, editor The Art of Natural Building and Building Without Borders

“Earthbag construction is the most green and sustainable method of construction that I know of and it just got easier. This book is like having a coach with you on site who shares his wonderful knowledge step-by-step. This is the best investment, in time and money, any Architect, Engineer, Builder, or Home Owner can make. I love this book.” Dr. Bill Taha, S.E., President, licensed in 28 states, Precision Structural Engineering, Inc.

The ebook is available for free with all new house plan orders through Earthbag House Plans and DreamGreenHomes.com.

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