Earth Coupled Floors

Ceramic tile floor

Soil-cement floor

Stone floor

Recycled brick floor

Earth coupled floors – high mass floors in contact with the soil below (slab on grade, tile, stone, CEB, earthen floors, salvaged brick) – are ideal for keeping homes cool in hot climates. They are not recommended for cold climates where underfloor insulation is best. Our earthbag roundhouse, which is in a hot climate, remains cool year-round due in part to the earth coupled floor. The indoor temperature is about 15 degrees F (8 degrees C) cooler inside than out, and the temperature remains nearly constant night and day. Plastic sheeting under the floor prevents wicking of moisture.

“Floors are often the primary link between the structure of a building and its foundations (the ground upon which it sits). Where floors are in direct contact with the ground, they can have a major influence on the internal climate by adding thermal inertia (capacitive insulation) which is assisted by thermal coupling with the mass of earth underneath the floor.

The coupling effect of the earth and building structure increases with depth. Walls and roofs can also be earth coupled if the structure is excavated below ground. Once a structure lies about 3.0 metres below ground, it has such great thermal inertia that it is no longer subject to day/night temperature swing, but only to slight effects from seasonal variation.”

Text source: TT Architecture
Image source: Ceramic-Floors.com
Image source: Rammed Earth Works
Image source: Inehome.com
Image source: Vintage Brick Salvage

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Zero Energy Earth Home in Texas?

Kelly and Owen,
I’d like to thank you for all of the wonderful information you have offered for free to the world! I’ve been following along for about a year now and it just keeps getting better and better.

I have a question about insulation and thermal mass. I live in Austin Texas and our summer nights are a lot of times only 20 degrees cooler than the day time high. Which that day time high can get to over 110F. If I build with only earth/adobe filled bags, I don’t think that the house would be very comfortable during the summer months. I’m planning on rebuilding a small dilapidated shed in about a year using the hyperadobe method. The shed will have plumbing and electrical. Basically I’m going to build it just like I would build a house for our family to live in full time. This is going to be a proof of concept to show my lovely wife that it’s not a bad idea and that a house built in this fashion can look professional.

So my question is, how would you go about insulating a building built with the hyperadobe method, or would you build using a different method?

Thank you for any information!
Mike

Hi Michael,
I just looked up what the year-round underground temperature is in Austin, TX, and noticed that it is 71 degrees F. You couldn’t ask for a nicer temperature to live in! A substantially bermed or underground home in that locality could easily become a zero energy home, as far as heating and cooling goes.

You are right that a solid adobe-walled home there would be too hot in the summer for sure. Yes, it can be insulated, either with exterior insulation, or by filling the bags with an insulating material, and this would help keep the interior more comfortable…but you are still going to need air conditioning most likely.

If it were me, I’d go underground!
Kelly

[Owen: This can include building above grade with earth berming/earth sheltering to reduce the risk of flooding.]

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Gernot Minke – Building With Earth

Special thanks to Eugene in Russia for the heads up on this great find. This earth building book by Gernot Minke’s is one of the most informative books on the subject, and now it’s available as a free download. How can you beat that? Thank you Gernot Minke for all you’ve done in support of the earth building movement.

From the Internet Archive, where you can legally download the book:

One of the most complete and up to date (2010) handbooks around this subject available. This volume is loosely based on the German publication Das neue Lehmbau-Handbuch (Publisher: Ökobuch Verlag, Staufen), first published in 1994 and now in its sixth edition. Of this publication a Spanish and a Russian edition have also appeared. While this is first and foremost a technical book, the introductory chapter also provides the reader with a short survey on the history of earth architecture. In addition it describes the historical and future roles of earth as a building material, and lists all of the signifi- cant characteristics that distinguish earth from common industrialised building materi- als. A major recent discovery, that earth can be used to balance indoor climate, is explained in greater detail. The book’s final chapter deserves special mention insofar as it depicts a number of representative earth buildings from various regions of the world. These constructions demonstrate the impressive versatility of earth architecture and the many different uses of the building material earth. Kassel, February 2006 Gernot Minke

Source: Internet Archive

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Adjusting the Moisture Content of Soil

You can adjust the moisture in your soil mix. In this case we’re using road base. You can see that this is too wet. If it looks glistening with water then it’s obviously too wet. If you squeeze it and see water coming out like this then it’s too wet. So you can take your digging tool – this is a grub hoe – you can mix drier soil with it until you get the right mixture. This is perfect right here. Let’s zoom in and take a good look at this. It has just enough moisture that when it’s tamped together it will turn into a hard block – a hard building block – and water won’t squish out of the bags.

Note: I look at every bucket of soil before dumping it in the bag to make sure the moisture content looks good. Sometimes the worker filling buckets makes a mistake.

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Adjusting the Clay/Aggregate Ratio of Road Base

All of our earthbag projects have been built using the same road base material. It has worked exceedingly well. After tamping, the earthbags are solid and turn into very hard earthen blocks. Here I am testing the hardness of bags on our roundhouse.

But from time to time I would see areas with less than optimal bonding on the various samples I’ve made. Usually you can’t see the results inside the earthbag, but the samples enabled closer examination. Some of the samples looked a bit granular (lacking in clay) and so I got to wondering if the mix could be improved. After all, we’re not buying an engineered mix for highway construction, just local material right out of the ground. In most cases that’s fine, but what if you want to achieve maximum compaction and strength? (Which reminds me, keep your soil covered if possible because rain will force the clay to the bottom and throw off the mix.)

You could pay extra for an engineered mix, of course, and be certain of an ideal ratio. But for us it’s cheaper to just add a little extra clay and then test the results, so that’s what I did. I made a sample earthbag with 5% extra clay to see how it would turn out. You could do the same thing with whatever type of soil you have. Make a few samples and then compare them after they dry.

Here’s the basic procedure. We typically use five 2-gallon buckets of soil per bag. This means each bucket is equal to 20%. I wanted to add 5% additional clay, so I prepared ¼ bucket of sifted clay and mixed approximately the same amount with each bucket of soil. The mix appears stickier and looks like it will produce a stronger earthbag.

Text for video available at my Naturalhouse YouTube channel.

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Cool Pantry Update

Cool pantry under construction

We’re making good progress on our cool pantry – a shed roof addition behind our kitchen. A cool pantry keeps food cool without electricity (although we’re going to use ours as a storage room). It was built during this year’s workshop. The roof is on, and the end walls (triangular areas above earthbags) are framed in and covered with tar paper and mesh. Now we’re ready for the exterior plaster and floor. It’s the most perfect earthbag structure I’ve been a part of. Everything is very plumb, level, straight and square. We tested some earthen plaster on the wall yesterday and from the experiment it seems plaster materials and labor is halved due to good workmanship.

We’re videoing every step of construction (mostly the earthbag work) and plan to create a full length earthbag video for sale. This project is very similar to building a small house and so the video should be helpful for many. It will likely take two months to complete the video, so be please patient if you’d like to get a copy. (No need to write and ask “when will the video be ready.” It will be announced here on our Earthbag Building Blog when ready.)

[Update: I’m shocked! The video is almost finished. The editing is 99% finished. There are a few details to add and then I plan to add the best YouTube videos at the end. The total length will be close to 2 hours. Stay tuned…]

Learn more about cool pantries.

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Building an Earthbag Home in Northern New Mexico

Building an Earthbag Home in Northern New Mexico

I just found this new blog by Aly B. Following her adventure will likely give you lots of ideas for your own home. Text below is from their site.

“How did I ever come up with the idea to build myself a dirt house? Last February I was on my way back from Egypt, long before Mubarak left, and felt miserably depressed that I had no home to go back to. During the course of the long airplane ride, I began to draw the home which has evolved from square to rectangle to dome to kidney bean to airplane hangar. After months of reading countless natural building, greywater, rainwater and permaculture books, I have landed at the design that I have today.

As I talk about later, my design has been guided by simplicity and efficiency. More than anything, what’s been most important to me is to live in a house that I myself, with no building experience whatsoever, can design, build and maintain. A natural extension of that has been the desire to live in a peaceful space. For me that means a home that’s in tune with nature, thus limiting the use of imported materials for construction, in addition to those that will be needed later on, such as for heating.

Construction will begin in April 2011! Follow the building process on my blog.”

Building an Earthbag Home in Northern New Mexico blog

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NPR Radio: Dirt Bag House

This just in from Joe Newman, who’s building his earthbag home in New Mexico.

“We have a locally produced show on NPR called Ozarks at Large. We recently had a 5 minute spot aired on earthbag building. We were interviewed along with another couple building an earthbag structure in Garfield Arkansas. Short interview, so my plugs for your website and blog, and for Scott Howards earthenhand website are not found in the audio but are found under the link to the interview. Go here: Ozarks at Large then type “earthbag” in the “search by keywords” box to find the program.”
Joe

Ozarks at Large

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Rasin Clinic Update

The Rasin Foundation Medical Clinic in Haiti is making good progress, as you can see by the following photos.

Rasin Foundation Medical Clinic in Haiti

Rasin Foundation Medical Clinic in Haiti

More info here.

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Instructable: Insulated Earthbag Foundations for Yurts

Insulated Earthbag Foundations for Yurts

This Instructable includes complete step-by-step instructions on how to make an insulated earthbag foundation. You can use the same process to make insulated foundations for any type of structure – straw bale, earthbag, cordwood, etc.

Yurts or gers are very efficient and practical in harsh, cold climates, as evidenced by centuries of use in Mongolia. Benefits of yurts include affordability, rapid construction, ease of construction, wind resistance, great looks and portability (ability to take your home with you if you ever move). You may even save on taxes since some jurisdictions do not consider yurts permanent homes.

Many people build their yurts on a raised wooden platform to reduce moisture problems. But wood is expensive and building a platform/deck requires a fair amount of tools and carpentry know-how. Wood is vulnerable to fires and prone to rot and insect damage. It also requires regular painting or sealing.

In addition to the many other uses for earthbags, you can build insulated foundations by filling the bags with insulation such as scoria. The benefits of the insulated earthbag foundation system described here include:
– Very low cost, especially if you can locate recycled grain bags from farmers
– Very simple construction using just a few tools most people already have
– Save energy and enjoy a more comfortable home because the floor and foundation are superinsulated (plus, there’s no wind blowing under the floor to suck heat away)
– No deep footings/excavation required (research Frost-protected Foundations for technical details if you’re interested)
– The finished floor can be raised above grade as high as necessary (Deep snow? Flooding? No problem.)

3D AutoCAD drawings show each step of construction.

You might want to follow the Earth-Sheltered Solar Canadian blog, who’s planning to build an insulated earthbag foundation that’s suitable for extremely cold climates. It’s the same process as outlined in this Instructable, but they will use a deeper trench with insulated earthbags below grade to create a Frost-protected Shallow Foundation (FPSF). Combine these two ideas – FPSF and insulated earthbag foundations as shown in this Instructable – and you’ll have everything you need to know for free.

You can read the complete Insulated Earthbag Foundations for Yurts article by Owen Geiger at Instructables.com.

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