[Strawbale] breathability of wood shakes etc

[Nancy or David Gray]

Hello, it is my understanding that the tar paper, if that is what you choose to use, is vapor permeable.  There are other waterproof, yet vapor permeable membranes also.
In most places code requires some sort of membrane between wood and earth or wood and render of whatever kind.  Think of laying a board on the ground, then think of laying a board on something between it and the ground.  What would preserve the wood best?  When you have that answer you will know what to do.   Best wishes, David Gray