We often talk about the extensive benefits of high-performance buildings: lower energy costs, more durable structures, reduced maintenance requirements and healthier interior environments. High-performance strategies can improve the lives of building owners and occupants. Beauty is not as quantifiable perhaps, but it can bring delight to life. And there is nothing more delightful than working on projects where the work of high performance also results in beautiful architecture. EASTON+COMBS, the architecture and design firm of Rona Easton and Lonn Combs, based in the Berkshire Mountains of Western Massachusetts, has integrated many of our best practices into the design of a new home in Egremont – all while crafting a thoughtfully designed and exquisitely detailed building.
This modestly sized (1800 sq ft) home consists of two buildings connected by an open-air breezeway, and was designed to be integrated into the unique topography of the site without destructive site work and extensive excavation. It is highly insulated, extremely airtight, and integrates an electric heat pump for heating and cooling. Built by Little Deer & Company, the building is poised not only to meet Passive standards , but also designed for easy integration of solar panels for net-zero energy in the near future.
The thoughtfulness of this architecture is evident not just in the striking sculptural results, but in the very fabric and structure of the building – the components, the assemblies and the process. Beauty is apparent every step of the way.
Airtightness Above All: The Wall Assembly
The wall assembly integrated many of the best practices we recommend to maximize drying potential and ensure airtightness. Walls are built with a 12″ vertical I-joist structural system with dense-pack cellulose insulation, with an R-value of 45. By using SOLITEX MENTO 1000 as the exterior weather-resistant air barrier and INTELLO PLUS as the interior air barrier, the walls are guaranteed to be airtight while also maximizing drying potential and preventing moisture from accumulating in the assembly. Dense packed hygroscopic cellulose insulation also helps diffuse moisture, and is a safe and non-toxic alternative to foam insulation. By including a service cavity inboard of the INTELLO PLUS, Lonn and Rona ensured the longevity of the interior air barrier by minimizing the number of utility penetrations through the INTELLO. The service cavity also provides an additional space between the air barrier and the drywall, a sacrificial layer likely to see many penetrations over the life of the building. Moreover, the horizontal battens that form the service cavity help to balance the pressure of the dense-pack against the membrane, and ensure that it remains evenly distributed over time.
To further ensure the longevity of the interior air barrier, American Installations installed the INTELLO Plus and insulation with a clever system of cardboard strips to further reinforce the membrane. When cellulose is blown behind the membrane, it increases the pressure on the membrane and shear on the staples that connect the membrane to the studs. By laying cardboard strips over the INTELLO and stapling through these strips, the pressure on the membrane is significantly diffused. This is particularly helpful if you intend to build without a service cavity, but in this case, it simply adds a further layer of protection to ensure the long-term performance of the air barrier.
The Rainscreen: Beautiful, Functional, and Low-Maintenance
On the building exterior, the architects used plywood sheathing, which is more vapor open than OSB, and applied a vented rainscreen. Rona and Lonn also went further to ensure long term performance and prevent condensation buildup by vapor venting the roof assembly. The roof is vented via a rainscreen cavity through a half-inch gap between the rainscreens of the roof and the wall, and a roof ridge vapor vent. Both the exterior walls and the roof are fitted with a standing seam metal finish, which significantly reduces maintenance requirements: the house will never need to be repainted, and there are no gutters to be cleaned.
A Cornucopia of Best Practices: Other Steps Toward High Performance
A number of other steps were taken to ensure long-term high performance. By designing the building with condensed interior cores, plumbing and electrical systems were kept out of the building’s exterior walls. This serves to significantly reduce the number of penetrations through the building envelope. The triple-glazed windows are flashed with EXTOSEAL ENCORS, a vapor-closed, water-tight, flexible tape. EXTOSEAL ENCORS significantly decreases the likelihood of leaks over the life of the building because its flexibility enables a single strip to be applied over the entire window bay sill and then approximately 4″ up the jambs – eliminating joints where leakage could occur.
By integrating numerous best practices – using both a vapor-intelligent interior air barrier and vapor-open exterior air barrier, choosing vapor-open plywood sheathing with a vented rainscreen, vapor venting the roof assembly, utilizing non-toxic insulation materials, and including a service cavity inboard of the interior air barrier – EASTON+COMBS have taken big steps on the path toward perfection in building design. We are truly inspired when exceptional designers like these are also committed to whole-building performance – and ensure a healthy, comfortable, and efficient home for decades to come.
All images courtesy of EASTON+COMBS.