We have a house in the Seattle area built in 1977. The house has R-16 insulation and is cedar-sided tongue and groove w/ old aluminum windows. We are planning on replacing the siding due to some dry rot and upgrading windows to Millgard aluminum. We are considering attaching R-10 rigid insulation to the plywood (to increase r-factor), prior to putting on the cedar siding. The incremental cost is substantial $5,500, for 1000 square feet, as new window sills will need to be fitted and drywall will need to be repaired. We are 100% electric and have a heat pump and our annual bill is $1,500. To reinsulated the entire house would cost roughly $15,000. Is it worth it ? The roof will need repairs in the next 5-10 years, would it be better to save and better insulate that? Any advice on how to value this would be greatly appreciated!