The High-Performance Home, Part 3: The Rainscreen
Rona Easton and Lonn Combs of EASTON+COMBS, the award-winning architectural office based in New Marlborough, Mass. have allowed Rural Intelligence to look over their shoulders (and those of their client) throughout the construction process of a high-performance home going up right now. This is the second installment of eight (or so — this is construction, after all) in a series that is giving us a lens into the building of an energy efficient house in Egremont, Mass.
The exterior wrap is on and the house is closed in.
By Rona Easton and Lonn Combs
The site has been quiet this month, but the exterior plywood and the smart building membrane, or wrap, are in place (holes in the wrap to be cut later for windows), closing in the building and allowing interior framing to proceed. We are looking forward to the upcoming delivery and installation of the triple-glazed windows.
Interior work can begin.
The exterior metal wall finish will be attached to the battens (the long strips of wood on the roof and soon the walls) which create a gap, or cavity, between the smart membrane and the finish, creating what is known as a rainscreen system — a key, passive environmental system that mediates between the exterior climatic conditions and the exterior wall.
Mockup built to study wall assembly.
The image at left shows a full-scale mockup we built to study the roof eaves at the corner of the building. The continuous, horizontal ventilation gap where the wall meets the roof is small, only half of an inch, but it is enough to allow air movement and small enough to minimize bulk water entering the cavity.
The complications, and maintenance, of gutters and roof overhangs are avoided because the system passively manages water rather than trying at all costs to repel it, much to our client’s liking. “I’ve found the experience of maintaining a house extremely frustrating, and wanted my new house to be very low-maintenance,” she told us. “I don’t want to have to find someone to clean my gutters ever again!”
As with the entire exterior wall assembly, the rainscreen system is another example of what we like to call an essentialist approach to design, where simplicity and practicality align perfectly not only with a beautiful aesthetic but also a finely tuned and efficient functionality.