HOW DO YOU STOP DAUB FROM CRACKING?

[catweazle]

Hello there,

I am currently restoring a 15th/16th century cottage in Norfolk. Some of the wattle and daub needs replacing. I have tried new daub, reconstituted old clay lump, to which I have added fresh straw, and a mixture of the two clays, but it always cracks within hours of applying. Yes, I am soaking the wall before hand. I have tried adding lime putty, as the old clay lump I have obtained does not seem to have any lime in it. It helps a little, but not much. The original infill that I have reworked is lovely, but I only have a small amount of this, yet even this cracks to a degree. I have tried using the daub thick, (about window putty consistency), and I have tried it with more water. The only mix I haven't tried is with cow dung, though the old stuff would probably have some in. Nothing seems to stop it cracking. Is it just the nature of the beast?

When making daub, Paula Sunshine says stuff in as much straw as you can. SPAB say it should only constitute I part !!

Also, how do you repair a wall in which only half of the hazel and daub has deteriorated without taking the whole thing apart? Paula Sunshine's Wattle and Daub book fails to tackle this problem? !

Yours in desperation....

 

[DaveBrigg]

Welcome to the forum. Hopefully some experts will be along soon, but in the meantime, could you say what else is in the daub mix? Is it just clay, lime and straw, or have you added sand? I have used a mixture of modelling clay, straw and some fairly fine sand out of the garden in equal measure, and it has worked quite well. Where fine cracks appeared after a couple of hours, the mix was still soft enough to be worked with finger tips to fill them in.

 

[robgil]

could it be drying out too fast? it has been fairly warm recently.

 

[catweazle]

Hi there,

I am sure there is sand in the new ready-mixed daub I have bought, but this was not local clay and I felt awkward using it as it was a different colour, (even though the building is not listed). I was advised to get hold of some local clay lump, which I have done, but I don't think this has anything in it apart from stones and flint. I will try adding some sand.
Actually I have just looked in my SPAB booklet and they do mention sand, though the original daub that I have re-used seems very similar to the clay lump, but lighter in colour and slightly less sticky. Yes, it is not ideal weather for doing this, and I am sure the heat is a factor, but it is quite cool inside the cottage yet the daub still cracks badly unless I stick a good dollop of lime putty in my bucket and mix it in. The outside daub I have covered over, and is not dry yet even in this heat, but still cracking! I think it may be that I am using a mix with too much clay in it. Perhaps I should try some of the SPAB mixes, but mixing it in this weather is no joke!
(I have smoothed over the cracks on the outside daub, but they are slowly starting to re-appear!)
Is it possible to use a cement mixer for this stuff, or does it need to be done by hand, or should I say feet ??

Thanks
Cas

 

[nozzaamazon]

I have had good success with clary straight from the gareden and mixed with straw that is chapped into 8" lengths. I put as much straw in as I can - its amazing how much you can get itn. I have added just enough water to work in the straw. No sand or lime needed.
If your just getting fine cracks then this is fairly normal and when limewashed they will disappear and look as per original panels. If larger cracks and your sure its not drying out too quickly (mine usually takes over a week to start to look dry) then perhaps your not forcing/compacting the daub enough. It really is quite hard work!

Good luck

 

[Hatster]

Totally non-sarcastic, and just intrigued - I suppose that saying you used 'clary' was a typo for 'clay'? You didn't actually mix clary sage with the straw, did you? Or is this a clever trick to make it moister?

 

[biffvernon]

I've got a lovely row of clary sage, just coming into flower now.

I suspect your mix has too much clay and not enough silt and sand. Try adding subsoil - the stuff from below about six inches underneath your garden surface. You need a mixture of grain sizes, the clays filling the gaps between the coarser material. And re-work the surface as it dries.