We bought a round house that we wanted to make cozier — so we added 2.5″ of polyiso fiberglass-backed foam to the inside walls, set furring strips every 16″ (try to do the math on a round wall) and then hung 3/8″ sheetrock.  All of this is being guided by Julian, a very forward thinking green builder and all around interesting guy.

Next steps: plaster the walls, install a kitchen.