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Case Study

A Durable Deck Ties This Home to the Landscape

Location: East Greenwich, RI

Meticulous flashing, non-toxic treated lumber, and a conservative design make this structure as sustainable as it is useful.

The large, wraparound deck not only creates a nice bridge between the house and back yard, it helps balance the entire house on the property. The eastern exposure is elevated above the sloping grade, offering shade and cool breezes in summer, while the southern exposure provides warmth on all but the coldest days in winter. The house is small, so extra outdoor space to enjoy the private wooded lot and abundant wildlife is welcome in every season.

Design approach: Connect the yard to this hillside home on both floors

The slope-side house never had a good connection to the back yard—only a small, concrete landing and four steps out the back door. Initially the plan called for a small backyard deck or patio as an outdoor living area. Taking a broader look at the overall landscaping and considering the awkward appearance of the small house on the sloping hillside, another idea arose: A wraparound deck would break up the long, blank wall of the house and offer cover for a ground-level patio below. Not only would this deck-over-patio combination give more usable space in the same footprint, but it would also visually connect the home to the terraced landscape.

Tight tie-in and efficient framing

Breaking into shingle siding to conventionally flash in a new deck ledger to the wall is risky business, so special aluminum ledger standoff brackets were used. The brackets could be spaced about 4 ft. apart, and only six shingles needed to be removed for each bracket. The brackets were also easy to flash into the tar paper WRB and the shingles.

Employing efficient design and framing techniques minimized materials, waste, and labor. A slightly deeper than usual integral beam meant fewer deck posts and corresponding footings were required. The extra beam depth also conceals a gutter on the backside, which collects water running off a rubber membrane laid over the joists to protect the patio beneath. The deck drainage system also diverts water away from the perimeter of the house on two sides, relieving moisture pressure on the finished basement. The deck joists were used at their full 12-ft. length rather than cutting them down to create a 12-ft.-deep deck. Ordinarily, 4 in. to 8 in. would have been cut off each joist and thrown away, not to mention the work to make the cuts and haul away the scrap.

Extra steps were taken during framing to ensure the long-term durability of the deck. Portions of the joists and the beam that weren’t covered by the rubber drainage membrane were capped with strips of waterproof membrane; leftover peel-and-stick flashing tape, tar paper, and synthetic underlayment from other projects around the home also were used. Cap strips were laid across the horizontal 2x4 guardrail and 4x4 posts before the top rail was placed. All the metal hardware (joist hangers, ledger brackets, post connectors, etc.) was isolated from the deck frame lumber using self-adhering membrane strips, which break the galvanic reaction between the hardware and the wood treatment and reduce corrosion.

Nontoxic, highly fire-resistant, low-maintenance, and durable sodium-silicate-treated Southern pine lumber was used for the decking and guardrail system. Stainless-steel fasteners give long-term service and allow for easy disassembly in the future. A unique guard-infill system made from tough, lightweight, braided polypropylene protects the spaces between posts, rails, and the deck surface; the netting is essentially soccer-goal netting.The black cord color almost disappears between the posts, so it doesn’t require cleaning like glass infill would.

High first cost gives long-term payback

The extra features such as the silicate-treated lumber and deck drainage membrane increased the cost of the deck compared to a conventionally built one, but the benefits (durability, low maintenance) were worth it. The extra work placing the membrane, capping joists, and screwing, rather than nailing, parts together added to the cost as well; but the expense and hassle were outweighed by the advantages of additional dry space beneath the deck, which provides a shady, dry sitting area that can also be used for storage and parking.The greater durability and end-of-life ease of deconstruction will more than make up for the costs associated with joist capping and screwing.

Lessons Learned

Delivery of the silicate-treated lumber took over six months, due to inadequate distribution on the part of the manufacturer. Shortly after the lumber was delivered, a local distributor began stocking it. Often, the desire to try new materials is thwarted when manufacturers don’t have reliable networks for distribution. This risk exists for many new-to-market green materials.

The larger-than-planned deck and building-length patio weren’t factored into the original budget. However, the costs were outweighed by the deck's assets: the deck adds balance to the house and adds a new dimension to the home by providing outdoor living space and a multi-use covered area.

General Specs & Team

Location: Georgetown, MA

  • Site Features
  • Grading improvements increased slope of grade away from the house
  • Deck drainage system (with gutter) connects to a drain pipe leading away from building
  • Retaining wall beneath deck made of stones from the site
  • Lighting
  • Existing wiring reused for lighting at door entrances
  • Solar accent lights
  • General Design and Construction
  • Designer/builder: Mike Guertin, in consultation with wife-architect and knowledgeable friends
  • Metal hardware isolated from treated lumber to resist corrosion
  • Drainage membrane protects joists and ceiling finishes and provides dry outdoor living space beneath that doubles as storage and covered parking
  • FSC-certified lumber
  • TimberSIL treated decking left unsealed
  • A drainage gap between the house and ledger is provided by mounting brackets that are flashed into the existing asphalt felt WRB
  • Stock lengths of lumber used for minimum cutting and waste

Image Credits: Mike Guertin, Charles Bickford/Fine Homebuilding

Content By GBA
  • USGBC
  • ASID