Existing 2 x 4 framed exterior wall

I am renovating a condo.  Condo Board regs prohibit any exterior changes that vary from original design.The exterior walls are 2 x 4 framed construction in climate zone 5.  No upgrades… I am renovating a condo.  Condo Board regs prohibit any exterior changes that vary from original design.The exterior walls are 2 x 4 framed construction in climate zone 5.  No upgrades…Read MoreGreenBuildingAdvisor