Oatmeal on the Dome

With winter rains approaching as fast as the new year, it was time to get back to building. Waterproofing the dome is the next task that I need to complete. My plan was is as follows: wire mesh over the insulation, to be covered with vermiculite concrete. On top of the vermiculite concrete, I planned to apply a hard, water resistant, stucco shell colored to match teh existing stucco walls.



I used chicken wire for the mesh; it took me just an hour or so to nip and tuck it into a dome shape. This was loosely wired to the wires securing the insulation. The idea keep the mesh loose enoughy that about 3/4 to an inch of vermiculite concrete could be packed between the insulation blanket and the mesh.


Next step: the dreaded vermicultite concrete! I had been procrastinating about applying the vermiculite concrete for some time. It looked difficult and potentially frustrating. I have to say that my concerns were unfounded --- it turned out to be fast, simple, and surprisingly easy!

I picked up a 3.5 cubic-foot bag of vermiculite from Sunset Nursery on Monday. Then yesterday waited indoors all day while the Santa Ana winds blew 35-40 MpH over the hills and canyons.

Finally today, the winds calmed; so, wrapped up in an old sweatshirt and a hat, I braved the sunless, cold morning air; gathered tools, concrete and fireclay; and opened the bag of vermiculite. I mixed vermiculite, Portland cement, and fireclay to a 10:2:1 ratio, then added water to bring the mixture to a dry, oatmeal consistency. I pressed the mix into the mesh, and evened it out with a wooden float, working the material like one would work plaster or stucco.

It took me about an hour and a half to finish off the dome. Its wrapped in plastic and covered in canvas tarps to keep it warm over night. I'm very happy about the way it turned out! I guess nothing to fear but fear itself....