Chainsaw Retrofit, exterior insulation, & add on rafter details

This one is a homeowner forum post rather than a news story, so there's not much here that applies broadly. A homeowner is rebuilding the roof on a detached 20-foot by 20-foot garage after removing rotted rafter tails, siding, and roof sheathing. He's doing what's called a "chainsaw retrofit," a technique where old roof edges are cut back and rebuilt with new framing so thicker insulation can be added on top of and inside the roof and walls.

His plan calls for roof insulation rated at R-26 on the outside layer plus R-23 on the inside, and wall insulation at R-6 outside plus R-15 inside, in a location on the border of climate zones 4 and 5. He's attaching new roof "sleepers" (framing strips that create space for insulation and let the roof surface be rebuilt) with long structural screws. He posted photos of his plan asking other builders to check his approach before starting work, and a building science expert who replied said the design looked good.

There's no product launch, rebate news, or program change here worth passing on. It's simply one homeowner's insulation upgrade plan for a garage, useful mainly as an example of how exterior and interior insulation layers can be combined during a roof rebuild, not something that changes what's available to you or your own house.