The house was completed in Feb. 2007. It was at the recommendation of the builder that we went with the 2x6 walls. In addition to the insulation, every opening was foam covered. In most homes, insulation is not even put in spaces less than 3 inches between studs. Those spaces in this house are all foam filled, even down to 1/4 spaces between studs, etc. I know cause I re-insulated it after the insulation contractor was all done. All windows are foamed in place. There are 2x12's between each floor (filled with insulation) and each floor has its own heat system. All interior walls are insulated. The Greatest thing is not the savings on heat and cooling (don't get me wrong thats great too) but how quiet the house is. We can have a [Sam Hill] raise party going but you can still go to bed and have piece and quiet.

IM A BIG FAN OF MULTI ZONE SYSTEMS, IF FOR NOTHING ELSE BUT BACK UP