Island House Makeover — Insulating the Skin
Winter has hammered Portland, Maine in recent weeks, and that includes Peaks Island, a 20-minute ferry ride from downtown in the Casco Bay. The weather has presented challenges, but it hasn't stopped work on the project Coastal Connection has been following there: the foundation-to-ridge structural reinforcement and deep energy retrofit of a hundred-year-old island cottage (see Slideshow).
When we visited the island in mid-February, Thompson Johnson Woodworking's project manager, Mark Pollard, wasn't wearing his tool belt. "I'm on light duty," he said. "I hurt my back shoveling snow." Added Pollard: "We're subbing out the snow removal now."
But carpenters Shane Fenton, Ed Muennich, and Chris Mitchell had their tool belts on (over coveralls and parkas), and they were hard at work, applying an air barrier of Grace Ice and Water Shield and an insulating skin of foil-faced rigid polyiso foam to the home's walls. Inside, the home's dormers and interior partitions were all framed up, said Pollard, ready for plumbing and wiring. "We're out of inside work for our crew," he said. "If the weather gets rough again, we either have to deal with it or take the day off."
Working in narrow paths shoveled between shoulder-high snowbanks reminiscent of World War One trenches, the crew worked its way around the building applying the air barrier membrane and piecing the two layers of foam sheathing into place around the window bucks and rafter tails. They sealed joints between the foam sheets using Dow Weathermate housewrap tape on the inner layer, and high-performance 3M 8067 all-weather flashing tape on the very outer foil skin. "The outer foil is the drainage plane," explained Pollard, "so it has to be as perfect as we can make it."
On the coldest days this month, Pollard said, the Weathermate tape was too cold to use. "We tried heating it up in front of the salamander heater," he says, "but that melted it." Finally, he said, he bought a plug-in therapeutic heating pad from the drugstore, and placed the heating pad with the rolls of tape inside an insulated foil "cold bag" from the grocery store. "That turned out to be perfect," he says. The crew couldn't wear gloves while handling the sticky tape, says Pollard. But he says, "We would keep our gloves in the heated bag, and when our hands got too cold we would stick them in there and warm up."
Working around the existing rafter tails at the top of the walls was tricky and labor-intensive. "We considered cutting off the rafter tails and wrapping the wall membrane up onto the roof sheathing," said Pollard. "But then we'd have to rebuild the rafter tails. And these ones are already here, and they're in good shape."
After the exterior skin is done and spray foam insulation is applied to the underside of the roof sheathing, but before the house is drywalled, Thompson Johnson plans to blower-door test the house for air-tightness, while they still have access to the walls and roof from the inside for spot air sealing. "We're hoping to hit 1.5 ACH50," said Pollard.