Cob Roof - South Room Progress

I plan to post a more detailed account the roof assembly once I decide on the water-proofing membrane and complete the work. In the meantime, I am providing this status photo to document where am at this moment.

The photo shows that the roof has been covered with a layer of cob. However; note that for this (roof) mix I used significantly less clay...so that after the water evaporates from the mix, the cob will be lighter.  The light mix mitigates weight as an issue for the supporting roof beams (Vigas).

The photo also shows that the surrounding parapet walls are taking shape but are still about a 12-inches from their final height.  I use my regular (heavier) cob mix for the parapet walls.

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Also, additional cob will need to be added to the roof to provide sufficient slope and contour to allow the water to flow out the drain pipe at the SE corner of the roof.

Here is recap of the built-up roof material used to date: 1) Ponderosa Pine beams (vigas).  2) Bamboo latillas.  3) burlap on top of the bamboo.  4) 2"-Rigid foam insulation.  5) 6-Mil plastic.   6) Light clay/straw cob mix.