Wrapping an Old House in a Passive House Puffy Jacket

To start the job, a carpenter tears existing siding off the old house. Thirty-year-old existing housewrap shows the effects of age.

EcoCor job foreman Dan Armstrong rips through the house’s existing roof sheathing and asphalt shingles. The roof will be cut back to the plane of the wall below, and an air-tight vapor control membrane will be applied to the existing wall sheathing below and integrated into the roof air barrier and drainage plane (a layer of ice and water shield). The wall and roof will then form a continuous air-tight shell around the house. Outboard of the wall membrane, the crew will apply an insulated assembly of wood I-joists and cellulose insulation.

EcoCor job foreman Dan Armstrong cuts the ends off the home’s existing rafters with a Milwaukee Sawzall. The crew will then run a new air-tight vapor control layer membrane up the side wall and onto the roof, creating an air-tight connection from wall to roof at this juncture.

EcoCor job foreman Dan Armstrong staples Pro Clima DA membrane to the existing sheathing. This section of the house is a relatively new garage addition with plywood sheathing; the older part of the house has sawn board sheathing that dates back to about 1910. The DA membrane will effectively air-seal both sections. According to architect Ken Levenson of Pro Clima distributor 475 High Performance Building Materials (www.foursevenfive.com), the DA fabric can be left exposed for about six weeks during construction, and will protect the home’s framing and interior finishes while retrofit work is in progress.

EcoCor job foreman Dan Armstrong de-nails the lowest course of shingles on the existing house roof, after chopping off the roof eaves and running ProClima DA membrane on the existing walls. Next, the DA membrane will be continued up onto the roof. Later, roofers will strip the shingles and apply ice and water shield membrane to the roof sheathing, integrating the roof air barrier into the wall’s air-tight vapor control layer.

EcoCor job foreman Dan Armstrong tucks ProClima DA membrane under the roof shingles. Later, this joint will be covered with ice and water shield, joining the roof air barrier to the wall’s air-tight vapor control layer at this juncture.

EcoCor carpenter George Reefer applies Pro Clima Tescon tape to the line of staples attaching the DA membrane to the existing sheathing. Staples are located at the wall studs. The tape covers the staples, and will also seal around the fasteners the crew will later use to attach wood I-joists to the walls at the same locations.

EcoCor carpenter Rich Perry builds a window extension buck assembly onto an existing window in the Newcastle “Ripple” house. The window bucks extend out to the plane created by the wood I-joists applied to the house exterior, and will have to be integrated into the air control layer in the center of the wall, as well as into the drainage plane layer at the wall’s outboard face. High-performance windows will later be installed into the “punched opening” created by the OSB bucks.

EcoCor carpenter’s helper Evan Drinkwater shims down an extension window buck for an existing window in the Newcastle “Ripple” house. Accurate, square, plumb, and level window openings are important, because the manufactured Passive House windows will need to be installed carefully into the openings.

EcoCor carpenter George Reefer applies Pro Clima Tescon tape to the joint where the OSB window extension buck meets the membrane-covered wall sheathing. Every joint where air could pass between the outer insulated wood I-joist assembly and the inner stud-frame wall has to be meticulously air-sealed, because this existing sheathing plane represents the “air and vapor control layer” for the wall.

EcoCor job foreman Dan Armstrong screws a wood I-joist into the existing wall framing through the newly installed air-tight vapor control layer of ProClima DA membrane. The new wall assembly will be air-tight and vapor-closed at the plane of the DA membrane and wall sheathing. The cellulose insulation in the I-joist cavities will be protected against air infiltration by a layer of ProClima Solitex Plus fabric applied on the outer edges of the I-joists. But the vapor-open exterior membrane, while providing a water-tight drainage plane, will still let the assembly dry to the outdoor air if necessary.

EcoCor job foreman Dan Armstrong screws a wood I-joist into the existing wall framing through the newly installed air-tight vapor control layer of ProClima DA membrane. The new wall assembly will be air-tight and vapor-closed at the plane of the DA membrane and wall sheathing. The cellulose insulation in the I-joist cavities will be protected against air infiltration by a layer of ProClima Solitex Plus fabric applied on the outer edges of the I-joists. But the vapor-open exterior membrane, while providing a water-tight drainage plane, will still let the assembly dry to the outdoor air if necessary.

EcoCor carpenter George Reefer applies strapping outboard of the newly installed ProClima Solitex Plus membrane. Siding will be installed over the strapping to complete the weather exterior. Windows, currently on order, will be installed later in the spring. But with the outer membrane and strapping complete, the wall can now be insulated.

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