Hi. We did exactly that during a remodel with New Day Construction on Seattle Home Remodeling. While walls were open, they added insulation, replaced drafty windows and sealed gaps. Our heating bills dropped noticeably the next winter. It was one of the best decisions of the whole remodel. Honestly, it’s much cheaper to add insulation while walls are already open than later. Ask about available utility rebates for efficiency upgrades, some can offset part of the cost. The house also feels quieter now, a bonus we didn’t expect.
