Mid-Century Modern DER
The house is composed of three single-story pavilions connected by a circulatory spine and enclosing open courtyards. The building envelope, comprised of 8″ minimally-insulated CMU, 2 1/2″ wood deck with 1/2″ of EPS and roof membrane, and large single-glazed aluminum-framed sliding doors, was a poster child for the bygone age of “electricity-too-cheap-to-meter”. This original shell had the stunningly low average R-value of 1.2 and was so leaky that the blower door was not able to get a reading.
Our clients had two goals that drove the design decisions: they wanted to flip the thermal performance from the bottom 1% to the top 1%, and they wanted to maintain Chermayeff’s original architectural expression. Achieving these goals in tandem provided some very difficult challenges to the design team. Luckily, these types of problems are some of our favorite to solve.
- The need to reduce thermal load led immediately to deciding whether to enhance the envelope to the interior or exterior. We chose to add to the exterior with 8” CMU block veneer laid up from an extended footing with a 3/8” polypropylene mesh cavity with 4” of polyiso insulation, mechanically fastened to the existing CMU substrate over a Carlise ‘MiraDri’ adhesive membrane that became the air barrier. In all we achieved an R-60 in the roof and an R-40 in the exterior walls and with a tested air tightness of 0.8 ACH50.
- Doors and windows were a particular challenge. In most cases, openings appeared as transparent floor to ceiling voids rather than punched holes in the masonry wall. Much attention was given to identifying a manufacturer to provide an efficient replacement for these full-height, 10-foot wide openings.
- Skylights were an integral component of the original design, essential to admitting light without the need of intrusive windows along the north, public facade. Their occurrence along the spinal corridor also served to accentuate this axis. This aspect of the original design was retained in the new, though the skylight wells became considerably deeper with the additional roof depth – resulting in slightly less glare, as well as a more restricted view of the clouds & sky above.
- The original Glulam beams were seriously undersized and, after exploring various complex and expensive ways of stiffening whilst retaining their aesthetic quality, it was decided that overlaying a completely new roof structure was the most practical course. This involved increasing the height of the building by 20”, but a massing study indicated to our clients and ourselves that this would be acceptable. Clear-spanning engineered I-joists were used to distribute the load around the perimeter. The new roof is capable of supporting both itself, the increased snow load anticipated due to better insulation, a PV array, and even a vegetated roof, should the clients decide to move ahead with those enhancements in the future.
- Renovations had been made to the original design following its sale in the mid 1960s. Bumping out the kitchen was a definite improvement over the former galley corridor and this was retained. But the addition of an atrium by enclosing one of the courtyards, and eliminating the original built-in living room seating in favor of installing a fireplace were markedly detrimental to the design, as was the replacement of the white VCT flooring with black slate. The fireplace subverted the value of the clerestory space because the seating previously under the clerestory and looking out was reversed, and the black slate diminished the value of the original skylighting along the spinal corridor.
- The building has no attic, basement, or garage. The clients’ commitment to the original design integrity put an extraordinary premium on space. We chose to install air-sourced heat pump cassettes, served from a single outdoor compressor / condenser unit. This enabled short duct runs (or none at all, in the case of the wall-mounted units) with cassette units located in space created by lowering ceilings in closets and the rear corridor.
- The interior finishes palette was substantially retained, including the bare CMU, the oiled wood decked ceiling, and the plain plaster partitions. Only the floor, now a pickled white Scandinavian soft wood in place of white vinyl is a modest departure from the original. Resurrecting the light colored floor of the initial design restored considerable value of the skylighting, which had been severely compromised by the black slate floor.
- We retrieved a single original fixture and had replicas custom made using contemporary LED lamping. In addition, we employed linear fluorescent pendant luminaires as well as switch receptacles for floor lamps to round out the palate of lighting solutions.