When Insulation in the Roof Isn’t There
This New Hampshire beach house may have a great view of the ocean, but there’s not a shred of insulation in the roof. What now?
Michael Buckley is on a tight budget, but he knows he’s got to do something about the problem. A house in his climate zone should have a minimum of R-38 insulation in the roof, and ideally more than that.
He’s mulling rigid sheets of polyisocyanurate foam installed between roof trusses, along with an aluminum/foam radiant barrier. He points to claims the radiant barrier adds more than R-15 in a layer slightly more than 5 mm thick. Can that be? he asks in a Q&A post at GreenBuildingAdvisor.
Absolutely not. In fact, Buckley is told, the product is nothing more than a scam.
But using sheets of rigid foam insulation does have possibilities. The real question is whether it should be applied on the inside of the ceiling, or on top of the roof deck, notwithstanding the fact his roof is only five years old.
Buckley’s request for advice, the subject of this week’s Q&A Spotlight, rings a bell with two other readers. Poorly insulated roofs, it seems, are nothing unique to New Hamphire.
If you're not prepared to rip your roof off to insulate, adding foam insulation between the rafters may be the easiest option for a cathedral ceiling. (Image from Fine Homebuilding Q&A: How to insulate a shed roof)