[URY914]

On the 2 x 6 exterior wall issue, it depends more on the type of insulation used to get the R-factor you are looking for. 2 x 4 walls with spray-in foam will give you about the same R-factor as 2 x 6 walls with cheap batt insulation. You can pay more for the wood in a 6" wall or pay more for the insulation in a 4" wall and come out with the same cost overall.