Energy Efficiency, Indoor Air Quality, Materials Efficiency, Design Innovation, Advanced Building Envelope
Super energy efficient 796 sf backyard cottage. The compact two-story form has three-bedrooms/one bathroom, and constructed with SIPs panels with a liquid-applied WRB, exterior EPS insulation, robust air-sealing, ductless heat pump, heat-recovery ventilation, metal siding with exterior trim over a rainscreen, altogether will dramatically reduce maintenance and energy costs.
The clients needed additional bedrooms, and the cost for building in the existing backyard, was substantially less than adding a second-story to the existing early 1900’s house. There will be a future breezeway connecting the two structures. The proximity to public transportation (easy walk to the McClellan St. light rail station, and many bus lines, removed the parking requirement, making the site layout more amenable to orient all the bedrooms to the south.
The SIPs panels went up quickly, which was critical as this took place in December, and the exterior was coated with the Prosoco liquid-applied Cat5 WRB, which provides a long-lasting air & water barrier. The WRB was able to be installed as soon as each set of panels was erected, not having to wait until the entire exterior was completed. The interior SIPs joints were also taped, and a consecutive blower door tests, performed by the contractor, show an extremely tight 0.57 ACH @ 50pa.
The Lifebreath heat-recovery ventilation system will provide constant filtered fresh air, and also designed to assist in circulating the conditioned air from the Mitsubishi ductless heat pump.
The flooring is Poplar over two-layers of plywood, over rigid foam on top of the concrete slab. No thermal bridging, as there are no wood sleepers in-between.
Lumicor translucent panels incorporated along the stair, end panel at the bathtub, and upstairs in an interior re-lite have a 40% recycled content.