Author Topic: Building with Cob Todays Hobit Home  (Read 4829 times)

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Ronnn

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Building with Cob Todays Hobit Home
« on: April 10, 2010, 06:47:33 PM »
Cob is much like adobe mud but with added straw. You put on the wall wet and with a blunt tool called a cobbers thumb you push down thru the new lump tying the abundant straw to the layer below. The definitive work on the subject is The Hand Sculpted House by Evans Smith and Smiley. It is the most sculptural material I have ever built with. It's very strong when done correctly. The book covers everything from site selection to a living earthen roof if that strikes your fancy. It is a methodology that, with a piece of land, would allow a working single mother to build her own cottage with no mortgage or by your leave from anyone. So long as you have a secluded site and keep quiet about it at the hardware store. Not every one is suited to do this of course. It is alternative home construction all the way. Much of your furniture can be made from cob incorporating rocket stoves or other wood burners into the mass of the house. If you wanted you could do all seating this way, also built in shelves or closets or sleeping platforms with a rocket stove flue below. The cottages are made of arcs and curves which makes for very strong, and usually have thick walls. The structures are small and the focus is on efficient use of living space and conservation of energy. Thermal mass like crazy. This building style evolved in Europe in the middle ages or before and was revived in the Oregon rain forests which is where most of the pictures at the link below came from. There are many seven hundred year old cob houses and barns in Europe. And soon migrated into northern california. It lends itself well to making small projects, benches, ovens, animal shelter these can be incorporated into outdoor covered dining areas or just a wall. Because every thing is mud including the exterior plaster or maybe a lime and sand render, things need a roof over them and exterior house walls need an overhang. As you will see if you look at the links these are not dank caves but inspiring living spaces.

You can view professionally made Cob cottages here:

http://www.ilovecob.com/ashan/cascadiacob2005/cob2k502.htm

This is a slide show that begins with some mosaic tile work but there are tons of pictures. I doubt many of these homes were permitted. Perhaps in Oregon but I'd be surprised.  I always include this next link because of the beautiful reciprocal rafter [ I use the term very loosely ] system. If you like the houses in the first hobbit movie you will love this place.

http://www.simondale.net/house/index.htm

Be sure to hit the `click here' button at the bottom of the page if you like this sort of thing. It is very organic stuff.

So that's my story and I'm sticking to it.

Ron

troy

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Re: Building with Cob Todays Hobit Home
« Reply #1 on: April 24, 2010, 02:57:58 PM »
Cobb walls are great for thermal mass and lousy for insulation.  So, while it may be ideally suited to mild climates, I would freeze to death here in Michigan if I had Cobb exterior walls.

Various estimates for the r-value of Cobb ranges from, r 0.3 per inch, to r 1.0 per inch at best.  So if your wall is a foot thick, which is a lot, you will have between r-4 and r-12 at best.  Framing, windows and penetrations will make the overall r-value even worse.  In my neck of the woods, I want r-40 or better in the walls and the ceilings and the basement, if I can get it.

Finest regards,

troy