Rooted in the Lowcountry: Designing with wood for sustainability and Southern style

July 10, 2017

Photo courtesy Crescent Communities

by Matt Cecere, AIA, LEED AP
A long, winding driveway in Bluffton, South Carolina, weaves through expansive maritime forest marshland full of live oaks and long-leaf pines before it opens onto the secluded Palmetto Bluff community. Residents and guests of Palmetto Bluff spend their leisure days enjoying lush, coastal scenery—kayaking in the marsh, birdwatching, biking, and hunting—and subtle hints of the area’s history. During the Antebellum era, it was home to 21 plantations, and in the early 1900s, a wealthy East Coast couple purchased and transformed it into an elegant country escape for New England elites. Here, the old South and the glamor of a Gatsby-esque era blend with modern design, modern users, and a new approach to building techniques, especially in the use of wood.

In the mid-1930s, a paper company, which had purchased the land intending to clear-cut the forest, chose to leave Palmetto Bluff untouched because of its striking beauty. That commitment to land stewardship is still evident through the Conservancy at Palmetto Bluff, founded in 2003 with the mission to protect and maintain the ecological and environmental integrity of the lands. The conservancy has been instrumental in protecting hundreds of acres under conservation easements, ensuring historic wetlands are protected, and maintaining food sources and habitats for regional wildlife, while also allowing the land to be managed as a resource for hunting, fishing, and other outdoor recreation activities. Residents and guests can also participate in research and attend sessions about the findings.

Aspects of the game hall during and after construction.
Photos courtesy 4240 Architecture

Aligning with a culture built around stewardship, and unique to the coastal region of South Carolina, the ‘Lowcountry’ style has a long history of influences. Stemming from native populations, Spanish explorers, and British-American settlers, Lowcountry architecture is a clear derivation of American colonial architecture, evolved over the past three centuries to address the site and climate. The quintessential building construction application in this region is known for directly responding to the ubiquitously swampy sites and subtropical climate. Constructed of timber frames on piers, buildings are elevated above the ground to keep dry and to induce ventilation from below. The roof forms maintain a simple, classical aesthetic with long overhangs to make room for deep, shuttered wraparound porches inviting in cool breezes and fragrant smells of the local flora, while protecting against violent storms.

Completed earlier this year, Moreland Village is a more-rural alternative to Palmetto Bluff’s first neighborhood, Wilson Village. The first phase of buildout spans 240 ha (600 acres), including 500 homes spiraling out from a hamlet of commercial buildings at the village center. Organized more like a camp than a gridded town, these buildings straddle a central path winding through the village. There is an outfitters used as a jumping-off point for residents’ outdoor adventures, the conservancy to teach more about the natural environment, and the Boundary, a clubhouse and social hub. Plans for future development phases include a real estate office, general store, and post office, which all connect to a great lawn and the maritime forest surrounding the village center.

As the Moreland Village project developed, the team—consisting of Crescent Communities, Choate Construction, Witmer Jones Keefer, and 4240 Architecture—worked closely with the conservancy to ensure the project aligned with the values of preservation at the core of the community. This effort was challenged by the harsh environment of coastal South Carolina, where forceful winds, heavy rains, and hurricanes can easily damage inadequately prepared buildings. These factors pushed the design team to find creative, project-specific solutions.

Aerial view of Palmetto Bluff marshland.
Photo courtesy Crescent Communities

Lowcountry architecture and the Boundary
The Boundary provides a place to unwind and connect at the end of adventurous days, with a restaurant, bar, art loft, and amenity areas extending from a central lounge in the primary building. Considering unorthodox spaces such as the smokehouse, game room, bowling alley, and bike barn, the design team expanded its research beyond Lowcountry homes to consider several distinctly local types of historic structures as architectural precedents. These included:

Elements from each of these were re-interpreted to suit contemporary programmatic needs while also exemplifying the intersection between seamless design solutions and environmental considerations.

The smokehouse
Taking cues from historical smokehouses (simple, solid masonry outbuildings with roof vents and ports for supply and exhaust air), the smokehouse at the Boundary is transformed into a display kitchen, timber-framed with a wraparound porch for guest dining. The structure uses a combination of preservative-treated southern yellow pine, ipe decking, and reclaimed heart-pine counters. Since all the wood connections needed to address wind-loading from hurricanes, fixed column-base connections were created to allow the structure to cantilever from the foundation. This solution affords completely open views of the marsh and great lawn through bronzed screens set in southern yellow pine frames.

The game hall
Similar to historic Southern ecclesiastic spaces, the game room features an exposed-wood structural system for the walls and ceiling. The primary wall structure is composed of flitch-plate columns, in-plane purlins, beams, and braces. The columns are 4x10s flanking 19- x 203-mm (¾- x 8 ½-in.) galvanized steel plates, which are welded to base plates bolted to the concrete foundation. Members spanning between columns vary in size from 2×4 to 4×8. All fasteners between the structural wall elements are hidden from view to give a clean, contemporary appearance.

The roof structure consists of partially exposed trusses with purlins and plywood sheathing. The trusses, composed of 3×8 heavy timber top and vertical chords, are bolted to heavy timber and 20-mm (¾-in.) steel rod bottom chords. These are topped with 4×10 southern yellow pine purlins. The flitch plates in the structural columns act as hidden tie-downs connecting the roof structure to the foundation.

This figure shows details of the game hall’s construction.
Images courtesy 4240 Architecture

The exposed-wood wall assembly is uniquely built, with structure at the interior clad with insulation and both interior and exterior siding. This required special construction sequencing, in which each section of wall was framed, sheathed, and then craned into place where the flitch plate connects each panel. Once this was done, electrical raceways were run in conduits to junction boxes penetrating through the wall siding, then insulation, sheathing, air barrier, drainage board, and siding were installed. This creates a highly insulated wall with minimal thermal conductivity, effective breathability behind the siding, and a beautifully exposed wall structure at the interior.

Similarly, the roof structure is used to house electrical and mechanical systems above a dropped slatted acoustic wood ceiling, located at the bottom of the top chord of the roof trusses. As with the wall assembly, great care was taken by the design and construction team to coordinate all systems and ensure no fasteners, conduits, or ductwork were exposed. Above the structure is a vented nail base with high-temperature roofing underlayment clad in 5V crimp metal roofing.

All wood structural members are specified as Grade A or better southern yellow pine to create  a refined aesthetic void of knots or checks in the wood. Further, all structural and nonstructural wood members are stained with a specially formulated, water-based, semi-transparent stain low in volatile organic compounds (VOCs) to achieve a whitewashed appearance. A similar strategy for the exposed wall structure and dropped wood slat ceiling is found in all primary public spaces, such as the dining room, art loft, flex space, and lounge (Figure 1).

Figure 2: A closeup of tabby concrete used for the bowling alley.

The bowling alley
Perhaps the most unique part of the Boundary is a four-lane bowling alley designed to professional-level standards in a flood zone. The alleys are equipped with a custom system that turns the area into a dance floor by removing gutters and replacing the negative space with bowling lane material to create a uniform surface.

The bowling alley is a great counterpoint to the rest of the clubhouse spaces—while these other spaces are framed and clad in wood, it has an organization similar to historic marketplaces (such as those found in Charleston), featuring massive brick walls with large openings to the public and light, airy ceilings. The difference here is the walls are not brick, but rather revival tabby concrete, a material unique to this region. Originally used as a substitute for concrete, the contemporary version is a slurry of cement and oyster shells, giving a rustic, yet permanent effect to the structure (Figure 2).

This material was placed in 100-mm (4-in.) thick, 610-mm (24-in.) tall lifts against the wood structure, both on the interior and exterior. The proprietary formula employed allows for cement to be washed from the face once the formwork is removed, revealing oyster shells while maintaining structural integrity. The installation and cleaning of the cement required there be an air barrier and drainage plane applied to both the interior and exterior surfaces, so all adjacent work is protected from water damage.

In the Lowcountry, hurricane-instigated flooding is a real concern. All buildings are raised 0.3 m (1 ft) above freeboard to keep them above flood zone. However, due to unique support requirements for the bowling alley, the floor could not be raised sufficiently to get the ball returns to the appropriate height. Instead, a waterproofed concrete ‘bathtub’ was created to ensure the ball return was protected.

Section details from the project’s bowling alley.

Similar to the game room, all mechanical, sprinkler, and electrical systems are concealed from view. To achieve this, the floor spans across the concrete bathtub to the masonry walls, which also allows for ductwork to be run in the crawlspace below the floor. The ductwork then extends up into shafts in wall chases. The ceiling structure in the bowling alley is similar to the other spaces, but here, since the mechanical system is run below the floor, the purlins are exposed, with the acoustic wood slat ceiling set in between them (while still allowing for the sprinkler lines to be concealed above). Combining the beautiful wood ceilings and massive tabby walls, along with a gorgeous section of cross-cut wood flooring, the effect is a space completely unlike any other bowling alley (Figure 3).

The bike barn
Design inspiration for the bike barn was found across the countryside of North Carolina, where tobacco barns are used to dry out tobacco leaves. These are similar to traditional barns, with two important exceptions: first, the siding is peeled open to induce ventilation, and second, there is a grillage of wood posts and beams supporting the racks of tobacco hung to dry. Similar to the tobacco barn, the basic function of the bike barn is to store and dry out bicycles, while also providing a place to maintain those used by residents of the community. Breathable basket-woven walls of old-growth cypress, stitched through a field of southern yellow pine poles, create a simple, yet powerful detail and formal expression.

The treehouse
Conceived as a whimsical counterpoint to the more traditionally derived building forms, the treehouse at the Boundary is a great place to birdwatch or just relax and stare at the sunset. Despite its name, the structure is not supported by the live oak tree in which it appears to sit, but rather ‘dances’ around it. Due to the close proximity to the tree’s roots, helical pier foundations minimize intrusions. Additionally, pits were dug before installation to ensure no piers would hit primary tree roots.

The primary structure is tapered, preservative-treated southern yellow pine with stainless steel trusses. Two viewing platforms are cantilevered out from the main tower like branches on a tree in different directions, and two sets of stairs wrap around the structure to access the platforms and the two levels of the Boundary as well as a pool terrace. The platforms are custom-cut around branches, and the railing is a combination of mill-finished aluminum and southern yellow pine.

The Boundary’s bike barn at dusk.

Southern yellow pine was used for all structural materials because it is cost-effective, native to the region, available in abundance, and has strong overall structural capacity. For all exterior wood applications, protection from termites, sun, sand, wind, and user wear and tear is key to the success and longevity of the project.

A mixture of G90-coated connectors and wood-preservative-treated southern yellow pine created a sound structure. The micronized copper azole (MCA) wood preservative treatment used for the project is more environmentally sound than the chromated copper arsenate (CCA) treatment used historically, but yields the same level of protection, because it is less corrosive to fasteners and hardware and can be in contact with aluminum. Copper bonds to organic matter in soil, becoming biologically inactive, and does not introduce toxins or other environmental impacts. Another benefit to this treatment is it has a more-natural brown tint than the CCA treatment’s trademark green.

The natural setting of the building made using natural wood siding a key value of the project team. Considering the harsh environment, the team conducted extensive research into wood siding applications. Cypress has been used in the South for centuries, with a proven track record; however, various cedars and preservative-treated pines were also considered, because cypress harvested for siding in recent years is new growth, with large growth rings.

Failure in new-growth cypress is related to lack of cypressine oil and growth ring density. Cypressine oil is a natural insect repellant for the wood, and is found in larger quantities when the number of growth rings in the wood is greater than 15 rings per 25 mm (1 in.)—even better at 25 rings per inch. For this reason, old-growth cypress was used for siding in Moreland Village. In order to break down the scale of the buildings and develop unique formal expressions for each, the siding was installed in various arrangements derived and re-interpreted from traditional siding patterns. Lastly, the natural beauty of the old-growth cypress siding allowed the team to utilize a custom whitewash stain that provides some protection while allowing the beauty of the wood to show through.

Detail of a sinker cypress stair.

Considering the sophisticated elegance of the place, ipe decking was used for all decking areas—a standard throughout Palmetto Bluff. The 5/4×6 ipe decking is installed at all exterior floor applications with countersunk and plugged fastener locations. Unlike some other, more-contemporary fastening systems, the plugged fasteners add a sense of craft.

Interior wood finishes
In addition to using wood for framing, walls, and ceilings, there are a variety of wood siding treatments, flooring treatments, and casework used throughout the Boundary. Several species of wood native to the region are employed, including reclaimed sinker cypress, heart pine, and white oak repurposed as flooring, casework, and the feature staircase. The most unique wood species is sinker cypress (i.e. cypress submerged in waterways for decades or centuries, salvaged, and then milled). This wood has a distinct discoloration from mineral deposits saturated deep into the wood fibers, and was used at feature locations like the main stair, casework, and bar top (a complete sliced log with pewter inlays).

Finally, to tie the spaces together, reclaimed and repurposed wood flooring from old barns in Ohio is used throughout the building. The finish treatment for these wood floors is a unique process. First, the wood is laid in place with all the scars from its previous life still present, then it is covered in a uniquely formulated paint that fills all the nooks and cracks. Lastly, it is sanded smooth and finished with a clear protective layer.

The cross-cut wood floors used in the bowling alley provide a counterpoint to the reclaimed plank-cut floors in the rest of the building, consisting of reclaimed wood beams of a variety of species, including oak, beech, birch, pine, and cypress (Figure 4). Cross-cuts are 25-mm (1-in.) thick pieces scribed into semi-round shapes, which interlock like puzzle pieces. Once sanded and greywashed, they are clear-coated. Although this was the most labor-intensive wood installation in the project, the result is an extremely beautiful and unique wood expression.

This is an exciting new building that nods to the past while seamlessly embracing techniques and technologies of the 21st century, as well as maintaining sensitivity to the environment through material selection, treatment application, and integration of systems. All the innovations developed by the design team maintain the Lowcountry aesthetic essential to the place while addressing the various spatial and programmatic needs of a state-of-the-art facility able to last the test of time.

Figure 4: A comparison of reclaimed barn wood floors and cross-cut wood floors.

Matt Cecere, AIA, LEED AP, is a principal at 4240 Architecture, and has been an enthusiastic leader there for 17 years. He brings attentiveness and curiosity to all aspects of design. Sustainability principles, rigorous material research, explorations of tectonics, and integration of energy-efficient systems are consistently employed in Cecere’s extensive history of crafting wood-framed and heavy-timber buildings. He has worked on projects such as visitor centers, welcome centers, and clubhouses in various regions of the country, including Colorado, California, South Carolina, and Florida. Cecere can be reached via e-mail at[10].

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