Insulation Retrofit Zone 6 – Roof Question

A homeowner in a cold climate (building zone 6) posted a question on an online forum about insulating an old house's roof, which has 2x6 rafters. The rafters are shallow, and the poster wondered how to reach a common insulation target (R49) using closed-cell spray foam, since doing so would mean filling the whole cavity and adding more foam below the rafters, which struck them as impractical. Deepening the rafters by attaching extra lumber alongside them, another common fix, did not seem workable for this house either. As of this writing, the forum thread had only one reply, a one-word question asking for clarification, so no real guidance had been posted yet.

This is a good example of a common attic and roof insulation puzzle in older homes with narrow rafters: hitting recommended insulation levels often requires either building down from the rafters with rigid foam, adding a service cavity, or considering an unvented approach in combination with foam, batts, or dense-packed insulation. If your own house has shallow rafters and you're weighing a roof insulation upgrade, the trade-offs between cost, headroom loss, and moisture safety are worth discussing with someone who can look at your specific framing and climate details before you commit to a method.