Hi folks I'm Matt from Devon, UK and I can't wait to start contributing here. I have been involved with new-build cob house building projects here in the SW of England and France, so if anyone is interested in earth/cob building techniques, hopefully I can help. - Matt
Here's a few photos of the most interesting one... Main part of the dwelling - the block work is usually stone-faced for prettiness, but on this one the owner is aiming for a sustainable house code 6 certificate, so the whole exterior will be insulated and lime rendered over... Going up...third lift of cob. Fast forward 12 months... Two structures (main house on right, and granny annexe on left, both linked by a glasshouse
Another enthusiastic welcome MattJ. As you can tell, there's lots of interest in alternative building and I can tell that I'm not the only one wanting to "pick your brain". Have you done much work with non-cob earth construction? I'd love to do cob, but there's no available clay within a reasonable area ... just the local sand-silt mix. Bill
Hi there. Cheers! Ask away... I have never done any building without clay. Luckily the owner has both the clay and a seam of sand on this property. There's plenty of clay down here though - cob houses are common in the villages. Unfortunately they had a good old time with cement rendering in the 50's and 60's, so a few of them have succumbed to the damp and badly need repair. If anyone is interested in perhaps building a cob structure in the future, then a garden wall is absolutely the best learning experience for cob. Build yourself something reasonably thick, with some curves here and there, and a right angle or two, and you'll have more than enough of a handle on the material. A water well cover is also a good project. A mini digger would be ideal, but if you don't have the access to one then it can be done by hand. We use a JCB3X backhoe loader, and trucks, on the building site. You might be interested to know that no cob touches our hands. A manure fork is used to handle the cob, and peel away excess from the top of the wall, and a heavy mattock for 'facing' the wall nice and flat. We use hardwood whackers to dress the cob, and these range from a rounded off cricket bat to a Thor's hammer design. I've seen photos of people working the cob with bare hands and feet and "thumbing" it into the wall. I can see how this would be therapeutic and fun, but if you're concerned about the work rate then you need a stout pair of walking boots and some hand tools. It's a lovely material to work with!
That looks stunning! And huge! I'm as new as you are here but welcome. We're probably looking at an extension or separate studio on the place we're hopefully sealing the deal on soon. Will be examining all options...
cob in the news thanks for the posts and pictures. as it just so happens the Mother Earth magazine has an article on cob construction this issue. what i'm not really sure of is how it performs in an area with high water table or flooding. also, i'm not sure what you mean by the word "rendered".
I'd be interested to read that. I don't know how it's done overseas, but we build a reasonably high plinth, which the cob sits upon. In old days, they built it up entirely in stone. We build up to height in block work, then face it with stone. Of course, proper drainage is key - especially somewhere like Devon. We render with lime, then a lime plaster and finally a lime wash. You can actually leave the cob naked, providing you have good enough roof coverage, but I think it looks unfinished.
A waterproof membrane used before the substrate goes on. The owner will collect water in 2 storage tanks fed from the slate roof outbuildings. He also has his recessed PV panels up there. Green roofs systems on houses are inappropriate, in my opinion. They do look very pretty, but the space could be used more wisely I think.