Earth covered oven

[tkoach]

I am going to bury my oven behind a retaining wall. I was wondering if anyone has done this. My biggest concern is that the oven will need to be waterproofed. I am planning to use an architectural membrane (bentonite clay or other type of foundation waterproofing) over stucco. Most membrane do not breathe and I was wondering if this will present a problem in that any moisture will not be able to escape out the "backside" only through the chimney or oven door. Wondering if condensation would occur under the membrane and then at some point freeze and create problems. I could create a breathing space and vent it out through the top of the membrane (similar to venting on the cold side of house insulation). Just wonder if I am over thinking this. Any thoughts?
Tony in portland