The overnight plumbing break flooded the newly built Passive House with more than a foot of water, some of which was able to seep into the outer insulated cavity of EcoCor's double wall system. Here, a worker pulls damp insulation out of the outer wall from inside the house.
This small but elegant home in Camden, Maine, was designed and b…
This small but elegant home in Camden, Maine, was designed and built by Belfast, Maine, Passive House builder EcoCor in collaboration with the owners. The Passive House envelope was completed using EcoCor's trademark panelizing system, but the homeowners took over at the painting and trim stage.
George Reefer/EcoCor
The overnight plumbing break flooded the newly built Passive Hou…
The overnight plumbing break flooded the newly built Passive House with more than a foot of water, some of which was able to seep into the outer insulated cavity of EcoCor's double wall system. Here, a worker pulls damp insulation out of the outer wall from inside the house.
George Reefer/EcoCor
Here is a view of the wall during remediation work after the flo…
Here is a view of the wall during remediation work after the flood. Drywall has been removed to a point above the water damage line, Roxul insulation has been pulled out of the inboard wall stud cavity, and sections have been cut out of the OSB air barrier in each stud bay to allow access to the outer wood I-joist insulated bays. Note the red color of the fluid-applied air barrier coating applied to the inside of the OSB sheathing during construction.
George Reefer/EcoCor
Another look at the wall after demo during flood remediation wor…
Another look at the wall after demo during flood remediation work. Drywall and Roxul rock wool insulation have been removed, holes have been cut in the OSB air control layer, and damp insulation has been pulled out of the outside cavity of the double insulated wall system.
George Reefer/EcoCor
Another view of the exposed wall system during water damage reme…
Another view of the exposed wall system during water damage remediation, the day after the flood occurred.
George Reefer/EcoCor
Open wall cavities under a window during flood damage restoratio…
Open wall cavities under a window during flood damage restoration work. The double wall cavities had to be exposed and dried out using heaters and dehumidification equipment.
George Reefer/EcoCor
Once the wall cavities were dried, the crew applied patches over…
Once the wall cavities were dried, the crew applied patches over the OSB air barrier using pieces of ZIP sheathing. Here, a worker applies adhesive caulk sealant to the original OSB air barrier before fastening on the patch.
George Reefer/EcoCor
EcoCor carpenter Richard Perry screws a ZIP sheathing patch over…
EcoCor carpenter Richard Perry screws a ZIP sheathing patch over the hole in the double wall air barrier layer after removing wet insulation and drying the wall assembly.
George Reefer/EcoCor
Here's a look at ZIP sheathing patches applied to repair holes i…
Here's a look at ZIP sheathing patches applied to repair holes in the OSB air control layer. The round holes in the center of the patches will allow fresh dry cellulose insulation to be dense-blown into the cavities.
George Reefer/EcoCor
Another step in the repair work: cellulose insulation has been d…
Another step in the repair work: cellulose insulation has been dense-blown into the cavity through the hole in the center of the ZIP sheathing patch.
George Reefer/EcoCor
The cut-out circles made when the holes were drilled into the ZI…
The cut-out circles made when the holes were drilled into the ZIP sheathing patches were replaced as plugs for the holes, then the disks were sealed using squares of Pro Clima Uni Tape (www.foursevenfive.com).
George Reefer/EcoCor
A Pro Clima self-adhesive membrane piece in place to seal the in…
A Pro Clima self-adhesive membrane piece in place to seal the insulation hole in a ZIP System patch in the double wall.
George Reefer/EcoCor
Re-sealing the repaired OSB air barrier layer after removing and…
Re-sealing the repaired OSB air barrier layer after removing and replacing wet cellulose insulation. After the repair, the house scored about 0.27 ACH50 on a repeat blower door test for Passive House certification.
George Reefer/EcoCor
EcoCor carpenter Richard Perry seals the joint between the fresh…
EcoCor carpenter Richard Perry seals the joint between the fresh ZIP System patch and the existing OSB sheathing air barrier using Prosoco fluid-applied membrane (the same material used earlier to address air leakage through the face of the OSB).
George Reefer/EcoCor
A completed, air-sealed patch in the home's OSB sheathing air co…
A completed, air-sealed patch in the home's OSB sheathing air control layer after removal of wet insulation and installation of new cellulose.
Some lessons have to be learned by doing. And for builders who specialize in advanced super-insulated construction — like Belfast, Maine, Passive House builder Chris Corson of EcoCor, LLC — some of that learning takes place in uncharted territory.
The past year has brought Corson and his crew a few of those lessons. First, Corson discovered that OSB isn’t necessarily an adequate air barrier material for meeting the strict Passive House airtightness criteria. Then, after solving that problem in a new house in Camden, Maine, Corson learned what happens when one of his airtight houses floods with a foot or two of water — from the inside (see Slideshow).
EcoCor’s wall system is an advanced assembly with an inner wall of 2×4 stud framing and an outer wall cavity framed up using wood I-joists screwed to the sheathing of the 2×4 core. The inner 2×4 wall sheathing forms the air barrier for the house. In recent years, Corson has developed a system for panelizing these superinsulated walls in a factory space in Searsmont, Maine. JLC covered the method in 2014 (see: “Panelizing Passive House,” Coastal Connection 6/1014).
Last winter, Corson says, he set one of his panelized packages in Camden, Maine. “They came to us with a Hawaiian and Japanese-inspired design concept,” Corson says, “and we turned it into something that could be built within their budget. We did our Passive House panel thing, and stood the package, and then they took over to install the ventilation system (under our guidance), and they did all the interior finish work. It’s a cute little house — about 1200 square feet — with cedar siding, cedar shakes, and a metal roof.”
Last December, when the panels were set for the Camden house but before drywall was applied, Corson tested the house with a blower door — and failed the Passive House specification. “We were at maybe 0.7 ACH50,” says Corson — outstanding for a typical home, but just a little shy of the strict Passive House 0.6 ACH50 requirement. “I said, ‘What’s going on here?’”
Corson had heard stories of other builders failing the tough spec because of air infiltration through the face of OSB sheathing. So he experimented by taping clear plastic over some of his exposed OSB walls with the blower door running. Sure enough, he says, the plastic “pooched out.” His solution was to coat the inside face of the OSB with a fluid-applied air barrier membrane from Prosoco. “As soon as we did that,” he says, “we blew about 0.28 ACH50.”
That lesson was learned, says Corson: from then on, he switched from regular OSB to ZIP System sheathing for his Passive House panels. “It’s about $600 more per house,” he says, “and it makes a perfect air barrier. It’s a no-brainer.”
Fast forward to June of this year. The new homeowners are almost ready to move in. They’re in the house working on the trim. They finish for the day and go home. When they come back the next morning, they can’t open the door — because there’s two feet of water pushing against it. A pipe fitting on the main water line (supplied by the city) has broken, and the house is flooded. Not a drop has leaked out. “All their tools were floating around in there,” says Corson. “It was like an aquarium.”
Ironically, says Corson, the fluid-applied flashing he put on the walls in mid-construction — which were never part of the plan before the blower door test results were too high — may have saved the house. Corson pulled his crew off other projects for a rush job to repair the water damage. “We had to tear off some sheet rock, pull the wet insulation out, dry everything out, blow in new insulation, and patch the holes back up and re sheet-rock it,” he says. “But without that wet flashing, the water could have wicked up the OSB and ruined the whole first floor. The wet flash literally saved the house.”
The house was built on a slab foundation, with polished concrete for the finish floor. “So there was no wood flooring to ruin,” says Corson. “Basically they lost some tools and we had to fix some walls. It was maybe a $10,000 insurance claim, that’s it.”
So does every Passive House need to come with its own bathtub drain from now on? We’ll let the experts debate that one.
