To Chris Corson, owner of EcoCor Builders in Belfast, Maine, wrapping a 2x4 house frame in a "puffy jacket" of I-joists stuffed with dense-packed cellulose insulation represents the state of the art in super-insulated Passive House construction. "You could build something as good," he maintains, "but not better."
Corson first demonstrated the method on a new house in Knox, Maine (see, "An Affordable Passive House, Part 1," JLC, 05/12, and "An Affordable Passive House, Part 2," JLC, 06/12). Applying the same technique in a retrofit also works, Corson says — but it's not always worth the effort. "I've had six people come to me in the past couple of years and ask me to do a Passive House EnerPHit retrofit on their houses," he says, "and I've turned them down. It just wasn't worth it. It's more expensive to do it as a retrofit than it is to do it new, and not every existing house is worth investing that much money in. I sent them to a weatherizing contractor."
This year, however, Corson accepted one of those jobs. Since February, his crew has been working to apply the puffy jacket retrofit to an old frame house in Newcastle, Maine, on a bluff overlooking the Damariscotta River near U.S. Route 1.
Corson's crew is only responsible for the exterior Passive House-inspired package; another contractor, Tim Andrews of nearby Nobleboro, Maine, is carrying out an extensive gut-remodel on the interior. In the end, the house will be a showcase of energy-efficient restoration. The owner, Deb Poor, is Corson's "ideal client," he says: "She wants to show everybody what's possible. She's willing to invest the money to do it right — she wants the job to have a ripple effect." Corson has been calling the job, "The Ripple."
Andrews' crew is also handling demo on the home's exterior — pulling out old windows, and stripping off existing siding and the hodge-podge of housewrap and tar-paper to expose the home's existing sheathing (boards on the older main house, and plywood on the garage addition). Corson's crew then comes in to stage up the walls and apply an air-tight wrapper of ProClima DA vapor-barrier membrane (see slideshow, "Wrapping an Old House in a Passive House Puffy Jacket"). Wood I-joists applied over the DA membrane will form the cavities for a super-insulating blanket of dense-packed cellulose, and as nailing for a vapor-open exterior drainage plane membrane, strapping, and wood siding. Plywood bucks will form the deep punched openings for new Passive House windows.
The final product may not perform well enough to meet the demanding EnerPHit standard, Corson says; the existing home's solar orientation and window placement provide an excellent view of the river estuary, but aren't ideal from an energy efficiency standpoint. But Corson says he'll get close — close enough for the house to stand out as another example of what's possible using careful craftsmanship and the right materials.