Structural EngineerCharles Saul Engineering
General ContractorW.R. Main
From the architect. Designed by BNIM, the 2011 AIA National Architecture Firm, the Midwest Retreat is located in rural Iowa. The retreat was designed as a venue for both social and business gatherings. Because of this dual use, the programmatic relationships and requirements depart in subtle but important ways from that of a typical residence.
The retreat is located on a bucolic 700-acre site in the rolling hills of rural Iowa. When originally purchased, the property contained a mix of prairie, woodland and former farmland. With assistance from the Iowa Department of Natural Resources, the owner has restored much of the fallow farmland and non-native woodlands back to its native prairie ecology.
The building is approached from the south, by way of an existing gravel drive that traverses this prairie and woodland habitat. The retreat is sited in an existing clearing, and is surrounded by restored prairie that is allowed to grow up to the building's perimeter. With its siting in this clearing, as well as its form and materiality, the building echoes the agrarian typologies of the region. The building is elongated in an east/west direction in order to maximize daylight control and to highlight views of the pond to the east and the lone tree to the west.
The functional part clearly separates the social spaces in the continuously-gabled wood volume above from the support spaces in the concrete box below. In addition to creating a clear separation of support and social spaces, locating primary gathering areas on the second floor provides access to views and increased opportunity for natural ventilation. At the functional heart of this second floor space is a large, flexible open area bordered by three fixed functional elements: a low kitchen, a large hearth and an antique bar previously acquired by the client. These key components provide definition to the space and support its range of social activities. The single bathroom on the upper level is configured in such away to allow for a high degree of openness for less private functions such as handwashing, while still allowing for enclosure of the more private elements. Each of the two guest rooms at the west end are designed so that they may serve as a sleeping area, office space or exercise room, and as such their openness is also heightened.
In addition to proper orientation, the project uses a number of other strategies to reduce its environmental impact. It is heated and cooled by a geothermal system, and the mechanical system is zoned to allow independent conditioning of the caretaker's unit. Closed-cell spray foam insulation in the building envelope reduces infiltration and the need for an additional vapor barrier. Operable windows and ceiling fans promote natural ventilation. Eight-foot overhangs are employed at both ends to shade the low-e glass. Reclaimed wood is used for interior and exterior cladding, and its natural preservatives ensure that exterior finish products are not required. No finish was used on this same wood at the interior walls and ceiling.
Because the retreat will be used intermittently, low-maintenance solutions are important. Instead of gutters, water drains directly off the roof into a French drain that runs continuously around the building's perimeter. At the east and west ends, water flows between deck boards, through drainage slots, and down the canted concrete walls. Mechanical inlets and outlets are protected from the weather, concealed at the top of the concrete wall behind the extension of the wood rain screen. The concrete base, naturally-preserved wood cladding, extruded aluminum windows and metal roof all contribute to this long-life, low-maintenance strategy.
The building is organized to achieve maximum efficiency and minimum waste. The gable is a continuous array of scissor trusses from east to west. Walls are framed with eight-foot studs that did not require cutting. Standard reusable concrete formwork establishes the two-foot module of the building. The wood cladding is coordinated with this two foot module inside and out; by employing a reverse board and batten strategy, the cladding adheres to an 8” module while allowing for the use of standard 7 ¼” boards. Space is enclosed and defined as minimally as possible, while still providing necessary programmatic separation.