Been thinking about a home setup..

First off I'd like to say hello to all here. I'm new and this is my first post but not my first time to these forums.

Anyway I've been thinking for awhile about housing designs and such that are sustainable, off grid and use local materials where possible.

I've thought about an Earthship type design but I don't like its concrete use. I really like the idea of cob homes as well as straw bale homes.

I'd like some input and discussion on a sort of hybrid home that is a mix of straw bale, cob, earthship like and similar. Like any issues to be concerned with using cob and such in place of concrete? Think it can be done?


Just to note I am fairly new to most alternative building methods and materials but have looked into cob and straw bale a bit. Forgive me if this post seems odd or something as I'm going on 4 hours of sleep with about 14 hours of awake and it's about bedtime lol.

Welcome Mark!

Yes, cob can be used in place of standard concrete if you fortify it.  The Romans used such a thing to make their aqueducts if you remember.  They learned to add volcanic ash (which contains quicklime - see below) google this for informative videos. 

On a cob or stawbale house you want the stem wall to be water proof/resistant, so it doesn't wick water up into your bales/cob.

Calcium hydroxide, traditionally called slaked lime, is an inorganic compound with the chemical formula Ca(OH)2. It is a colourless crystal or white powder and is obtained when calcium oxide (called lime or quicklime) is mixed, or "slaked" with water. It has many names including hydrated lime, builders lime, slack lime, cal, or pickling lime. It is of low toxicity and finds many applications.

Concrete is such a great building material because of two properties. First is its compressive strength. Along these lines adobe is similar (although concrete has more strength per cubic inch).  Second, is its weather resistance where it far surpasses adobe.

Concrete's weakness is its shear resistance (or is ability to with stand lateral forces which as you might get in an earthquake).  To work around this we usually put steel rebar in as a skeletal structure.  To accomplish the same with adobe we add straw (at which point is is now cob).

You still have the problem where adobe and cob are not weather resistant but you can deal with this other ways.

If you are going to use cob instead of concrete and steel you just need to make sure that you have dealt with the weather issue.  A cob is going to need to be much thicker than a concrete and steel wall also due to the lack of chemical bonds in cob that you have in concrete.

Hi,
I'm a newbie and I would just like to throw in a possibility.
HEMPCRETE.  Hemp fiber, lime, water
It is 1/6th the weight of concrete, becomes harder than concrete as it actually petrifies as time passes.  Good R value.  Can be used in a variety of ways and from what I understand it does not splay out like would be the case with concrete so I imagine it can be moulded like with cob.
You can spray it like shotcrete, or make bricks or sections of walls or a few other ways and if I understand, will work as a foundation as well.
Here are a few examples:
http://www.youtube.com/watch?v=TMNBz0qx_Gc&feature=related
http://www.youtube.com/watch?v=wRtDh6YUt-0&NR=1.
http://www.youtube.com/watch?v=1Ft-AzLdXjU&feature=related
http://www.youtube.com/watch?v=tjhzo1Y38uI&feature=related
I do not have first hand experience with the product but I've been thinking this is now my prefered choice
Would love to hear if anyone has used this building method.
Was part of organizing and building a strawbale house in '97 and you will love living in one if you go that route.
...~*~...

"Hempcrete"?  'scuse me, but where are you going to find enough hemp fiber to build a house? (Don't answer that question, please.)  By definition, "adobe" is sand/clay/straw.  It needs no alteration to become "cob".  (Adobe is essentially an Arabic word that predates "cob" by a dozen centuries.)  Adobe is a fantastic building material (if you don't use old techniques in earthquake country...the oldest standing building in California is the chapel at San Juan Capistrano...1782!).

I have been inside many of the old missions when the outside temperature ranged between 104-107° F.  Inside temperatures hovered around 68°.  No electricity, no AC, no fans...nothing except good design accompanied by local (free) materials.  Unfortunately, at the time Junipero Serra walked (he refused to ride a donkey) from San Diego to San Francisco building 21 missions along the way, earthquakes were an unknown quantity.  Many have since been damaged/destroyed by 'quakes.  Modern technologies can circumvent those problems.

[As a side note, during the American Revolutionary War, Fra Junipero Serra (a Spanish citizen) collected donations from his missions (mostly unpaid Indians) and collected $137 which he forwarded to a General named George Washington.]

Adobe remains a viable building option.

John,
you seem offended that I brought a new possibility to the table.
I never said cob was not a good idea, I think cob is great.  perhaps if more people knew about hempcrete, supplies would also be more available as the public demanded it.
Don't be afraid, take a peek at hempcrete 
...~*~...

Not to worry.  I am not offended by new ideas.  However, I cannot go to Home Depot and buy a truck load of hemp, and certainly would not plant enough of my own on my property to cover my needs of home construction.  For silly, idiotic reasons, many laws and regulations have been passed restricting the "cultivation" of one of the world's most useful fibers.  The petro/chemical industry were behind the ban once they saw competition for their products.  It has many other uses, and I have even heard it has some medicinal uses as well.  (Lord knows it helped my sister in her final years when main-stream medicines could do no more.)

Edited to add:  If you could find it in sufficient quantities, hemp would be a good substitute for "straw".

Cast Earth info http://www.castearth.com/Pages/cedesc.html

And Concrete/cement alternatives  http://www.marklaurence.com/sustainability/concrete_alternatives.html

light clay-straw could be considered a hybrid of cob and strawbale even though it was around before strawbale.  Straw is mixed with clay slip and packed into forms within or outside of a wood truss or timber frame.

I like the link to cast earth.

I'm going to be teaching some classes on straw-clay walls this spring and summer with Earthen Hand Natural Building.  You might like to learn with the pros.

I really liked this Danish house I saw once that used mini strawbales.  They just recalibrated the bailing machine, I think.

Also, you might not know it yet.  There is StrawJet!  Its amazing:

http://www.strawjet.com/index.html