cob houses

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rhubarb

Joined: 08 Aug 2005
Posts: 49

Posted: Sun Feb 15, 09 8:26 pm Post subject: cob houses

hi everyone..
now that i have an expanding family i'm becoming more and more concerned about leaving a green planet for future generations and bringing my kids up in a healthy and peaceful place.. i've been doing a bit of research into building our own home and came across info on cob houses.. has anyone built their own home or know anything about this as i would be very grateful of any input or opinons anyone can throw my way..
cheers
ruth
xxx

gz

Joined: 23 Jan 2009
Posts: 8918
Location: Ayrshire, Scotland

Posted: Sun Feb 15, 09 8:31 pm Post subject: cob houses
There was an exhibition at St Ffagan's(Welsh National History Museum) about cob/clom a couple of years ago. The house in the museum, Nantwallter I think, is worth seeing. They would be able to give you the names of other people to contact- probably Gervase knows them too?

vegplot

Joined: 19 Apr 2007
Posts: 21301
Location: Bethesda, Gwynedd

Posted: Sun Feb 15, 09 8:33 pm Post subject:

There's a bit of revival for cob built houses. You could start by visit CAT (Centre for Alternative Technology) or asking for information on the cob courses they run. There are also a number of useful books available online from their website.

Cob is a clay based earth mix with chopped straw, farmyard manure is often added, which is built up in layers to form a solid wall. The exterior is rendered in lime (never use cement) and the interior either with clay or lime or even earth (as long as it has a high enough clay content). It need good footings to keep it's feet dry and a good hat (over hanging roof, often thatch). Many a cob building has been ruined by unsympathetic or restoration. Avoid the use of modern paints either inside or out as they can prevent the building from breathing.

RichardW

Joined: 24 Aug 2006
Posts: 8443
Location: Llyn Peninsular North Wales

Posted: Sun Feb 15, 09 8:53 pm Post subject:
You will need either a mechanical mixer or lots of helpers. Richard

vegplot

Joined: 19 Apr 2007
Posts: 21301
Location: Bethesda, Gwynedd

Posted: Sun Feb 15, 09 9:14 pm Post subject:

RichardW wrote:

You will need either a mechanical mixer or lots of helpers.

Richard

Or both

chez

Joined: 13 Aug 2006
Posts: 35935
Location: The Hive of the Uberbee, Quantock Hills, Somerset

Posted: Sun Feb 15, 09 9:52 pm Post subject:

I agree with going to visit CAT. And a friend of mine lives in a cob cottage in Devon that she has been renovating. I've got a book somewhere about alternative building methods that's got some info about cob in it; I'll see if I can find the reference. If I remember rightly, there is a modern way to do it that involves compacting the walls mechanically in 18 inch steps, which then allows you to build them up more quickly.

vegplot

Joined: 19 Apr 2007
Posts: 21301
Location: Bethesda, Gwynedd

Posted: Sun Feb 15, 09 10:19 pm Post subject:
Mechanical compaction is often reserved for earth walls in which the mix (a clay ricj earth, no straw or manure is used) is drier than cob and requires heavier compacted to bind the particles together. As cob is wetter it only needs tamping rather than compaction but doing this mechanically using a plate vibrator can speed up the process and is certainly less tiring. Edit: Sorry, being pedantic.

chez

Joined: 13 Aug 2006
Posts: 35935
Location: The Hive of the Uberbee, Quantock Hills, Somerset

Posted: Sun Feb 15, 09 10:23 pm Post subject:

vegplot wrote:

Edit: Sorry, being pedantic.

Yes, I think it was the vibratey thing that I read about - I didn't take it all on board as I was concentrating on the strawbale bits.

vegplot

Joined: 19 Apr 2007
Posts: 21301
Location: Bethesda, Gwynedd

Posted: Sun Feb 15, 09 10:25 pm Post subject:

Chez wrote:

vegplot wrote:

Edit: Sorry, being pedantic.

Yes, I think it was the vibratey thing that I read about - I didn't take it all on board as I was concentrating on the strawbale bits.

Much more interesting

chez

Joined: 13 Aug 2006
Posts: 35935
Location: The Hive of the Uberbee, Quantock Hills, Somerset

Posted: Sun Feb 15, 09 10:31 pm Post subject:
Rhubarb - there are various people in various stages of eco-build here; we are kicking around the idea of a strawbale one.

vegplot

Joined: 19 Apr 2007
Posts: 21301
Location: Bethesda, Gwynedd

Posted: Sun Feb 15, 09 10:36 pm Post subject:
The fireplace back in our new build is going to be built in rammed earth.

Gervase

Joined: 17 Nov 2004
Posts: 8655

Posted: Sun Feb 15, 09 10:44 pm Post subject:

There's an excellent and very cheap book by Jane Schofield on building with cob, published by the Black Dog Press of Crediton - Amazon has it, I believe.
Also, take a look at the Cob in Cornwall site, where you'll find all sorts of links, plus details of a more advanced book by Adam Weismann and Katy Bryce on building with cob.
Cob is an excellent material, but it's hard work, and you'll need a lot more clay, straw, muck etc than you ever believed you would. Mechanical help - unless you have a willing army of volunteers and half a lifetime for the project - is pretty much essential.

Bulgarianlily

Joined: 01 Jun 2008
Posts: 1667
Location: South West Mountains of Bulgaria

Posted: Mon Feb 16, 09 8:44 am Post subject:

I would start by taking a good look at the soil you are likely to use for building. If it hasn't got a good clay in it, forget cob, you don't want to be trucking in the right soil over any distance. If it is clay, then I would look at light straw or sawdust clay, that cob is heavy stuff, and needs to go on thickly. My favourite book is 'Build it green' by Clarke Snell and Tim Callaghan, that covers a lot of methods. I think cob is great for thermal mass, but I personally perfer something with more insulating value. We are working with the 'light' cob mixes and cordwood here from next month, if anyone wants to come out for a visit!

Tavascarow

Joined: 06 Aug 2006
Posts: 8407
Location: South Cornwall

Posted: Mon Feb 16, 09 12:44 pm Post subject:
I would build with strawbales if it was me. A lot faster & cheaper on the labour front unless you are going to do it all yourself & your soil is the right consistency.

rhubarb

Joined: 08 Aug 2005
Posts: 49

Posted: Sun Mar 08, 09 10:40 am Post subject:
hey guys.. thanks for all the info.. am going to look into doin a course at some point but as the wee one is still breastfeeding its a bit difficult.. also need to sell our property down south first..i did like the sound of a straw bail house but the hubby is a bit conventional where as i would live in a cave.. need to get him round to my way of thinking..lol.. i'll keep planning.. take care xxx

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