Progress continues on the Passive House deep energy retrofit we've been following in Brooklyn, New York. In late April, contractor Jose Maldonado's crew was working on the roof. A rooftop access structure had been framed and insulated. Rooftop deck insulation was complete, and a membrane roof installed, topped by a protective course of asphalt roof insulation. Still ahead: construction of a rooftop patio.
When JLC visited, carpenters were working on the insulation details for a roof parapet at the top of the rear addition for the residence (see slideshow, " An Insulated Roof Parapet"). Unlike the older existing parts of the building, the new structure at the rear has to meet current New York City building codes for fire-resistant construction in attached housing, explained Passive House consultant Cramer Silkworth. That means non-combustible construction — in this case, reinforced concrete masonry walls. Equipping that wall with Passive House levels of insulation was a challenge.
The design team's ultimate solution was to clad the outside of the masonry block walls with an exterior insulation finish system (EIFS), consisting of expanded polystyrene (EPS) foam, covered with wire lath and a cementitious weather coat. The insulation jacket extends all the way up the side walls of the building, over the top of the roof-edge parapet, and down the inside face of the parapet to join with the insulated roof. The continuous insulation ensures that all of the masonry mass is contained within the heated mass of the building, with minimal thermal bridging.
To insulate the parapet, the crew attached 2x4 nailers to the poured-concrete top cap of the masonry parapet wall, using cut nails and powder-actuated gun nails. Then they cut foam to fit the top and sides of the wall, and set it in a bed of mortar. The final step is to finish the foam insulation in protective coat of galvanized wire lath and cement. For more details, see slideshow, " An Insulated Roof Parapet."
Renovating Brooklyn brownstones is Jose Maldonado's bread and butter. Not all jobs require this level of energy efficiency, he says, but as time goes on, he hopes to focus mostly on the deep energy retrofit niche, taking advantage of his Passive House builder training and certification.
Maldonado's crew is taking the advanced Passive House detailing steps in stride, and Maldonado says they don't need a high degree of supervision during the day. Maldonado comes to the job twice a day: Once in the morning to plan the day's work, and once at the end of the day to check on progress. Says Maldonado: "I'm a big believer in personal management. Most of my guys have been with me since the beginning. I tell them: 'You're taking responsibility, you're working to provide for your family. It's up to you to keep improving your skills.' If any of them wants to try to learn something new, whether it's new materials or new trade methods, I'll give them a chance to work with it and gain that capability."