While you can’t wrap a ton of oven brick in a vacuum bottle, you can slow heat loss by raising it up off (or out of) the damp ground. Traditional Canadian clay ovens were even built on wood frames, which is possible when the masonry is thick enough to prevent the wood from getting too hot (over-firing can be dangerous). Other insulative plinth material might include lightweight stone like tufa or pumice. In the 1980s, Alan Scott, called by some the grandfather of modern wood-fired ovens, popularized a practice of building ovens on a lightweight slab of concrete made with lightweight aggregate such as pumice, perlite, or vermiculite. He further reduced heat loss by extending the rebar through the formwork onto the tops of the side walls, effectively “hanging” the slab (and oven) on the supporting walls. Removing the form left about an inch of air gap to isolate the entire oven structure from the base. That isolation effectively broke the thermal “bridge” that otherwise allowed heat from the oven to leak into the base.