The New Norris House wall assembly utilizes advanced framing techniques and a rainscreen wall construction. Constructed of Atlantic White Cedar (AWC), the cladding of the house uses natural materials much like those found on the original Norris cottages of the 1930‘s. Atlantic White Cedar has a natural weather resistance and is a native material to this region.
In conventional wall design, a single barrier building skin acts as a “all-in-one” layer to keep out rain, retain conditioned air, and to resist the forces of wind & air pressure. The pressure differential created by a conventional wall design is a major cause of moisture infiltration. A rainscreen, or pressure equalized system, uses 3 layers, a vented exterior cladding, an air space and a moisture barrier. Initially, water is deflected from the wall construction by the cladding. All moisture remaining is drained vertically and/or evaporated by the movement of air within the air space.
Specifically in The New Norris House, the batons that create the air space were canted to increase water drainage from behind the AWC cladding. Also, a bug screen that will prevent the regional dirt dobber from nesting and damaging the wall construction adds a layer of moisture protection during times of precipitation. The AWC was finished with Cabot’s Bleaching Oil.
The structural framing of the New Norris House wall assembly was built using 2x6 wood framed walls rather than conventional 2x4 framing methods. Using 2x6 studs at 24” on-center, this construction method resulted in a 17% reduction in lumber thus a 17% increase in insulation. Rigid insulation was also added to the exterior of the wood framing, behind the weather barrier, to reduce the effects of thermal bridging.
If you are interested in learning more about rainscreens in residential construction here are a few links to get you started.
an article on rainscreens:
and a more detailed report from DOE’s Building America specifically for houses in Mixed Humid Climates:
The New Norris House is a design/build effort from the University of Tennessee's College of Architecture and Design. Began in 2009, the home was designed and built by UT students in collaboration with Clayton Homes. The built project is now complete and the final phase of the project has begun. A team of 4 people (2 living in the home, and 2 graduate researchers) will rigorously document the experience via qualitative assessments and quantitative measurements, posting results to this blog.