[Cob] Lime Plaster Failure

[Kindra Welch]

Hi Bill - I love a good mystery!

I see two types of cracks … vertical and horizontal.  

Both of your vertical cracks appear to me related to hydration of the clay behind the lime plaster. My experience suggests this could be from exposure or could also be from wicking through the stem wall, or perhaps a bit of both.  Limewash will heal cracks and protect walls from exposure but could also serve to seal in moisture coming up through the stem wall.  How is the drainage around the house?

The horizontal cracks in the second two photos are a bit more of a mystery.  The diagonal line off the lintel log suggests structural issues.  Do you have any pre-plaster pics of that wall?  Or a photo of the entire elevation?  Is there a bond beam in there anywhere?  Why do the cracks  follow a slight color change in the plaster?

Kindra