Built around the perfect wall design specification originated by Joseph Lstiburek of Building Science Corporation, this home in Texas was featured on the American Institute of Architects (AIA) Austin Home Tour 2016. Architected by Eric Rauser of Rauser Design and built by Matt Risinger of Risinger & Company, this brick-and-mortar (actually, make that wood-and-metal) realization of the perfect wall concept was carefully constructed to deliver over a 500-year life cycle—and in doing so promotes a redefinition of the term sustainability.
In his original perfect wall white paper, Lstiburek wrote: “In concept the perfect wall has the rainwater control layer, the air control layer, the vapor control layer and the thermal control layer on the exterior of the structure. The cladding’s function is principally to act as an ultra- violet screen.” Against that canvas, Rauser designed a 1,450-square-foot, two-story home with a simplified yet architecturally interesting profile, not unlike the iconic Monopoly game pieces.
The home has an exoskeleton of all-metal corrugated siding and Galvalume metal roofing panels, deftly covering the rest of the perfect wall structure layers beneath, including: A 1×4 pressure-treated lath rainscreen; Two layers of 1.5-in. Polyiso rigid foam board insulation; A 40-mil, peel-and-stick air, water, and vapor barrier; A layer of 1/2-in. oriented strand board (OSB) sheathing; And a final interior layer of 1×6 pine boards installed on the back side of exposed conventional wall studs or ceiling rafters. The resulting inside-out approach to interior surfaces requires no drywall layer, lending to the unique look of all walls and ceilings. The exposed pine board surfaces, wall studs, and ceiling rafters are simply finished in white, zero-VOC paints—a room-by-room display of the great bones artfully designed by Rauser.
During one of his dozen-or-more hourly perfect wall presentations from the great room of the house over the October 15-16 AIA Austin Home Tour weekend, builder Risinger walked an attentive audience through some of the key design elements of the home, where creatively and thoughtfully assembling common, locally-sourced, off-the-shelf building components with the perfect wall approach leads to extreme longevity and serviceability of the structure. In his affable presentation style, Risinger described how many of these conventional products were used in unconventional ways, furthering a consummate focus on ultra-long-term sustainability. “Note that this house was designed with no roof overhangs,” said Risinger, as he tapped his laptop to project another under-construction photo of the house. “That enabled us to cleanly wrap the entire roof and the exterior walls by using a single length of house wrap, avoiding seams and potential leaks down the road.”
As for that all-metal exoskeleton, any suspected problems beneath can be uncovered and corrected in a non-destructive manner. “All of the metal panels are simply screwed into place,” said Risinger as he continued his talk, “so they can be easily removed and replaced with no damage to the house.” An open pier-and-beam foundation below with a generous crawlspace enables easy access for troubleshooting and correcting potential plumbing problems, as a contrast to most homes in Central Texas that have their plumbing systems buried in solid concrete foundations. And a set of wall-mounted Mitsubishi Electric mini-split HVAC systems require no ductwork, and are easily replaceable after their expected 25-year life cycle. “One could easily get the entire HVAC system removed and replaced in less than a single day,” Risinger noted.
So, enjoy the images here, which were provided courtesy of Austin architectural photographer Leonid Furmansky. If you want to dig deeper into the perfect wall concept, see the links below.