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Hi there!

I'm a Swede with a long passion for DIY, hydroponics, alternative energy and similar activities. I've been pondering about buying myself some land and building my own home seeing as living in the city is becoming more and more expensive, it's just not sustainable.

Some questions:

Considering my climate (70-90F summers, 0-20F winters, lots of rain), is there any modification I would need to do to my cob-mix?
My main concern is spring/autumn where we have periods of constant rain. I know that adobe buildings in desert climates can last for millenia, however I've never seen any in areas of rain and snow.

If I were to have the building semi-underground, so that one wall would be against soil, would I need to use polyethylene or would the cob/adobe made from the same soil work by itself? I've been reading a bit of Oehler's book, but so far I haven't stumbled across anything suggesting the use of cob/adobe.

I'm fairly new to building and have lots to learn, any help is greatly appreciated. 
 
                                          
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you would probably want to do the wall with polybags being as the cob adobe would absorb some moisture with out some form of barrier and if it absorbs moisture than you have the potential for mold you can always do a composite build i was thinking that on my build which is a vertical wall inground with masonry piers for the structural strength and to support the roof beams i would overlap a sheet of poly every 48 inch as an additional moisture barrier
 
Doug Gillespie
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In general, I would think that for free-standing (non-bermed) walls, cob should be fine in your climate as long as it is coated with a lime paster.  While the freeze-thaw cycles might not be as extreme as what you will face, cob houses (when properly coated and maintained) have lasted for centuries in very wet areas of the UK. 

As for the bermed section, I'm of the opinion that putting a cob wall against an earthen embankment is lily-gilding.  You already have your thermal mass in the earth you've dug into, so why build an earthen wall between you and the earth?  I would probably use another method for walls below grade.  You will definitely need some sort of moisture barrier for the bermed portion, regardless of the type of construction, and depending on the site may also want french drains uphill from your barrier as well.

Doug
 
                        
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Thank you both for your great answers. I'm currently looking into land and so far it seems that it will probably be flat, so I'm pondering wether to dig it down or just build on ground. My main concern is heating during the winter.

I'll keep on reading and post as I go. Again, thanks!
 
ronie dee
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Location: NW MO
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Honken wrote:
Thank you both for your great answers. I'm currently looking into land and so far it seems that it will probably be flat, so I'm pondering wether to dig it down or just build on ground. My main concern is heating during the winter.

I'll keep on reading and post as I go. Again, thanks!


For heating check into rocket mass heaters:

http://www.permies.com/permaculture-forums/1078_0/alternative-energy/rocket-stove-and-butt-warmer
 
                        
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Thank you but I was already planning on using one! ^^

I have some experiences in rocket stoves from before, really looking forward to moving up to mass heaters. I'm heading out to the woods this weekend to see how the soil is for making cob test out a few ideas (combined with a nice BBQ!).
 
Dale Hodgins
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    You'd be wise to check out cordwood/cob since you are in a much more extreme climate than cob is normally built in. Check out a wood chip clay and straw Clay insulation. Both of these are practiced in northern Germany and I think they would be more suitable to your climate than cob. Wood chip clay also has the advantage of drying out over a much shorter time so that you don't get caught half finished when the cold weather arrives. I live in a much warmer climate than you but have determined that cob is just too inefficient thermally. I do intend to use it on the interior for trombe walls and for a rocket mass heater. The advantages of thermal mass are most pronounced in areas with a large di-urinal range in temperature. During your winters you will need heat most of the time so all of this mass would be wasted unless it is externally insulated. The little bit of wood you save by building with cob will pale in comparison to the huge amounts of extra firewood required to heat and ill-conceived home built from the wrong raw materials for your climate.
 
                        
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Thank you Dale! I had a feeling that cob wouldn't cut it in our semi-schizo climate. Though I like the idea of cordwood, I'm not sure about the quantities of wood I'd be able to gather. Economy is of the issue, labor is something that we have in abundance.

How would thick adobe bricks (with straw/sawdust in them), plastered with cob, coated with lime work? Earthbags/superadobe?

 
Jeanine Gurley Jacildone
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I thought there were some of the best examples of cobb in the UK that were hundreds of years old - lots of rain and snow there.

Have I mistaken the type of contruction?
 
Kay Bee
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Location: Jackson County, OR (Zone 7)
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there is a repeated comment in the Cob Cottage book by Ianto Evans that I thought made a huge amount of sense... something along the lines of a cob house needing a good hat and a good pair of boots in a climate that gets significant rain throughout the year.

Basically a good foundation and a water-tight roof with appropriately sized eaves.
 
Joe Woodall
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Honken wrote:
Some questions:

Considering my climate (70-90F summers, 0-20F winters, lots of rain), is there any modification I would need to do to my cob-mix?
My main concern is spring/autumn where we have periods of constant rain. I know that adobe buildings in desert climates can last for millenia, however I've never seen any in areas of rain and snow.

If I were to have the building semi-underground, so that one wall would be against soil, would I need to use polyethylene or would the cob/adobe made from the same soil work by itself? I've been reading a bit of Oehler's book, but so far I haven't stumbled across anything suggesting the use of cob/adobe.

I'm fairly new to building and have lots to learn, any help is greatly appreciated. 


Hello Honken,

It sounds like your area is not a problem, you just should become more exact upon what it is, you really want to build. For Earth sheltered structures -Yes, you will need a moisture barrier !  Mr. Oehler's PSP method - while Great in a pinch or for emergency structures, if you have a few extra days to build in & a little bit of funds, there are much better and very permanent wall selections,  certainly better than wood - let alone plain, Adobe Blocks or cob in that situation. 

First About Above Ground:

When we build a Georgia Adobe Structure, we always insulate the structure - be that within the structures walls, or on the outside & all depending upon just what were building. For example: If were building an Adobe Block Wall , we could easiest have 6 inches of closed cell foam insulation sprayed onto the outside of the building walls, just after the wall construction was completed. This would give us, the thermal mass desired inside and the water tight structure outside. A simple connection of wire lath , mortared into the Adobe Blocks joints, provides ample connection for the foam to hold onto the wall and the exterior finish is done much as  a spray stucco finish.

One could also lay your Adobe Block, so as to have a hollow middle area, that would incorporate a foam sheet core laid within it but, rarely is that a wise choice , as it cuts your 2 Block - Adobe wall's Thermal Mass, into 2 halves  and also requires more engineering , just to stabilize the walls load bearing ability; as well, as one must also include, that admixture at least into the manufacture,  of your outside Adobe Blocks ingredients.

If your building above ground your going to need a proper foundation and also a stem wall , so as not to have wicking of moisture into your Clay / Sand wall mix , when rains flood onto the outside wall of the building,  so don't start laying Adobe's until your above the 500 year flood level.

Underground or Earth Sheltered Structures:

If your building sub-terrainialy and you want to use Carbon -0- Earth Mixes again, as your selected material, your going to need a permanent form, just to hold that earthen material together. For most single story Georgia Adobe Structures , we choose used automobile tires , as that they last for centuries , when tires are buried and plastered , they don't give off any adverse emissions and when pounded with a proper Earth mix you basically have a 300 to 400 pound steel belted brick. Outside of that, one will of course insulate the building with more closed cell foam sprayed or sheet form and provide a proper moisture barrier lining, to create a sealed envelope structure, inside the earth. 

I hope, some of that helps you with your choices & remember to only build where the location is 100% paid for - secluded & not regulated by government building inspections, or you are very likely if you choose "Alternative Materials " to get to spend lots of your money on over engineering , re-drawings and concrete in place of Earth.

Best Regards,
Joe Woodall, Rogue Eco-Architect & Managing Partner
Georgia Adobe Rammed Earth & Renewable Energy
Commerce, Georgia 30530 CSA
001-706-363-6453
Http://www.georgiaadobe.com

 
Dale Hodgins
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          Dale here regarding wood chip Clay. I made some blocks using a fairly damp standard cob mix and an equal volume of woodchips. The resulting blocks dried rockhard. Wood is a much better insulator than pure cob and these blocks readily held nails. This nail ability would make this a great material to use as infill on a post-and beam structure. Here in Canada tree trimmings from residential properties are commonly run through chippers by tree service companies. The resulting chips are a waste product which is given away. I've used these chips under my children's playsets and to build paths at a muddy jobsite. The leaves and needles can be sorted from the mix through sifting and by tossing with a hay fork from one pile to the other in a brisk wind. Another source of woodchips is scrap from demolition sites which is sometimes run through a large Hammermill. Be sure to not accept material which has lead paint, asbestos or other contaminants.

    Your country has huge amounts of boreal forest which have been replanted. Much of this forest requires thinning and by contacting those in charge of this operation you may find a very cheap source of wood. Small diameter poles can be joined with X bracing to create any width of wall you desire. A floor mounted jig can be set up so that you produce uniform wall trusses from this material. This sort of structure will go up much faster than one of pure cob and the wood chips wick moisture to the surface so you get a faster drying time. If you decide to do anything like this I would gladly send you photos of exactly what I mean. Good luck and happy building.
 
Dale Hodgins
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    On my test blocks the ones which I'd left without Earth plaster dried much faster than those which where covered in a smooth cob mixture. The greater surface area and exposed woodchips were exposed to the sun and wind so the moisture was wicked away. If you build with this double post and beam wall truss system you will be able to get your walls and roof up quickly in one season. Then you will have the option of postponing cobbing if the season has gotten away from you. The next spring you can concentrate on infilling the walls. A front-end loader on a farm tractor would be an ideal machine to use for both mixing and lifting this material to scaffolding. Plywood could be screwed against the faces of your wall trusses and the material could be shoveled into the wall in a similar manner to rammed Earth. But because your infill material is not the primary structural component of your building it would not have to be hugely compressed. Simply stomp it into place so that it all sticks together. Any accidental air spaces will simply add to your insulation value. Feel free to contact me if you decide to go ahead with a similar system to this. You may find that you're able to charge people for removal of useful wood debris. I have found many ways to get paid to haul away materials that I need. I was paid to remove a very high quality house. I had it moved and my family lived in it for 14 years. The acquisition of this house was the best financial move I have ever made.
 
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