lime and cob

[Anonymous]

We have some 150 year old untreated cob walls in our house.

2 problems. There has been shrinkage of the earth /straw filling over the years. What is the best stuff to fill in the gaps? Weve tried lots so far with varying degrees of success but have founf nothing really good. Perhaps someone has a recipe?

Also a problem with limewash. It seems to be cracking and flaking overnight and dampening the clay beforehand has no effect. What am I doing wrong? Am I going to have to resort to modern paints?
Celia

 

[Anonymous]

Celia

I've not had any dealings with Cob , however the symptoms you are describing for your limewash would indicate too thicker mixture. Are you mixing it to a transluant consistancy and applying several coats ?

 

[Anonymous]

I've tried 2 areas, 1 with thick stuff and 1 thin. Both were as useless as each other!
celia

 

[Anonymous]

Perhaps Mike Wye can help? - they seem to know about cob construction down in Devon.

I bought their practical lime dvd recently and can recommend it. I does feature a bit of building cob walls, plus lime rendering and washing.

Interesting alternative finishing plaster technique here too - I've tried 2 different methods so far with some success.


http://www.mikewye.co.uk/mikeprices.htm#video

 

[Anonymous]

re Paint:

Are you referring to just small cracks in the paint? If so, this is normal enough, as lime shrinks as it dries. Another coat will fill them just fine, if thats what it is.

Modern paints on cob would be most unwise.

Re cob:

http://www.ihbc.org.uk/Cob_Paper/cobindex.html

http://www.buildingconservation.com/articles/earth/earth.htm

NT

 

[Anonymous]

SPAB has several publications you may find of use - Jane Schofield on both lime and cob in particular.

See link below:


http://www.spab.org.uk/bookshop/limeplasterearth.html

 

[Maris]

There is a really nice book just out, called 'Building with cob' by Adam Weisman and Katy Bryce, otherwise known as the 'Cob in Cornwall' company. There is a lot of useful information in there about cob repairs. I think that they have a website too.
If you're up north (in Devon or beyond) then there is also the Devon Earth Building Association who should be able to advise you. The more local the advice, the better, since cob structures can differ a lot from place to place.

We've made some repairs to our cob walls*, and used sub-soil from our back garden - since thats what would have been used originally - plus fresh straw, and water. Enough water to make the mixture sticky, but not runny. The we threw it at the walls. Great fun. Seems to have held well so far.

There will probably be several layers of repairs like this, if the house is more than a century old. We've noticed many different phases of build and repairs in the cob throughout the house. including an area stuffed with wallpaper, an old plastic bottle filling a crack, and sections filled with wood and stone then rendered over with earth plaster.

*We did do a weekend course first