Cob house

[KathyLauren]

This weekend, I dropped in on an open house at a cob building workshop. I thought some folks might be interested. Cob is a mixture of clay, sand, straw and water. The exterior will be finished with plaster to waterproof it before the rainy season.

[Nomada]

Absolutely! Any more pictures or info? Where was it? I love the recycling of that window. I've become a bit obsessed with salvaged windows coz I'm wanting to build a small greenhouse if I can.

[grahamhobbs]

Cob is the traditional technique in many parts of England, especially Devon in the South West, and look very picturesque with their thatched roofs. One thing in the photo the wall looks quite thin, perhaps only 9" or 12" whereas in traditionally here they would be at least 18". Also the finish on yours looks quite smooth, here we lay the clods one on top of the other and trample on them to compact them and then shear the sides off with a spade just to staighten them up a bit, but still quite rough to provide a good key for the render.

[KathyLauren]

Here is another pic of the same project. It looks like the walls are about 12" thick. They were straightening the interior walls with a handsaw. It looks like they are leaving the exterior rough for the rustic look.

The workshop was on one of the Gulf Islands off the west coast of British Columbia. The climate is similar to that of the British Isles.

They don't have the roof on yet, just a tarp thrown over the rafters, but it certainly won't be thatch! Most likely steel, I expect.

[Nomada]

[quote="KeithBC"]
The workshop was on one of the Gulf Islands off the west coast of British Columbia.
[/quote

Guess I'm not going to that then!

Thanks for posting it though, I love seeing things like this. It's something I'd love to learn how to do one day!

[Mrs Moustoir]

Some friends of ours renovated a cob house in Brittany a few years ago.

A local chap helped them rebuild one of the walls with a lovely mix of mud, straw and cow poo which was then rendered to make it waterproof.

[grahamhobbs]

KeithBC, thanks the 2nd photo makes it much clearer. With 12" walls, I guess you are only going to one storey.

Regarding the cow poo in the mix. I am never certain whether this is a necessity or just the product of getting your cows to do the mixing of the clay and straw by being peened in and trampling on it.

[scrap]

Not sure either,but the cow poo does come full of finely chewed grass fibre.
Perhaps it was the lazy option...

[KathyLauren]

KeithBC, thanks the 2nd photo makes it much clearer. With 12" walls, I guess you are only going to one storey.

It is going to be one and a half storeys: the second floor is in the attic space, with gable end walls and dormer windows. The cob isn't supporting any structural load - that's all timber frame - so it is just carrying its own weight. I don't know if they are planning to use cob all the way up the gable walls.

Will cob not support its own weight past one storey? I would have thought that, as long as the wall is vertical and is well anchored to the timber frame, it would.

[grahamhobbs]

KeithBC, cob houses in Britain are often 2 storeys and take the loads of the 1st floor (is that your 2nd floor?) and roof, but as I have indicated they are usually thicker, frequently 18" or 2' thick. I have only built one low single storey cob building, so I am no expert but If the wall is not taking any load then I sense that a 12" wall would be ok up to about 1 storey, but much after that I would start to worry that it might become unstable with a tendency to bow outwards. Ties at first floor level would help restrain it. Good luck and keep us posted.

[KathyLauren]

I'm not sure I'll have anything further to post. It's not my house, and the open-house for the workshop was only one day. I can't even see the house from the road, so I can't report without trespassing.

The cob wall is well anchored to the timber frame using nails partially driven into the timbers and then embedded into the cob. Their longest span of wall without a timber is probably no more than ten feet, so I'm guessing that it is going to be pretty solid.

[vancheese]

It looks Simular to our outdoor kitchen and other building here in hungary! The only problem with it is that Mice and other animals bury into it! Any ideas how to repair this?

[freeforexsignal]

As the discussion about health, "green" living and "green" housing moves forward, we are discovering that many of the best solutions are actually very old, low-tech ideas. For years, infant formula had been promoted as a "modern" solution; today
The production method for cob is about as "green" and as low-tech as you can get. The large amount of heat energy required to produce most brick materials is not needed to make cob. Not much energy is required for transporting materials. Frequently, the right kind of earth is found in sufficient amounts right at the construction site. No power machinery is used. All you need is about a dozen of your friends and family. Earth, sand, water and straw are mixed together with bare hands and feet! When the material reaches the right consistency, it is scooped up into balls called "cobs." Cobs are stacked and packed into walls and shapes like domes, window benches, curved walls, nooks, window openings, or just about anything that the imagination can conjure up. No internal form structures are required, so there are no limits. Wiring and pipes are set into the walls as they are formed. With no hammers or loud power tools,

[grahamhobbs]

Freeforesignal, just to clarify the good points you raise, the 'earth' for making the cobs should not be topsoil but the sub-soil and this needs to be clayey. Sand is not essential to the mix. And it is better to use the feet of cows rather than your own, although perhaps less fun, as otherwise it can be rather tiring on all but the tiniest of buildings.