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Southern Pine Stands up to Tough Marine Environments
Wood is one of the most economical and versatile construction materials used in the marine environment, and pressure-treated Southern Pine continues to be preferred for use in a long list of marine applications. Marine designers, contractors and specifiers favor treated wood because it is readily available, easily repairable, and extremely durable. When it comes to floating docks and piers, wood decks are lighter, requiring less flotation. Environmentally conscious marina developers also point to the fact that wood is renewable and requires much less energy to produce than steel, aluminum, or concrete.
To assure long-lasting service in demanding marine environments, pressure treatment with preservatives is the most effective method of protecting wood. Southern Pine is the most treatable of all softwood species. Its unique cellular structure permits deep, uniform penetration of preservatives.
For most marine construction, waterborne preservatives are preferred. These treatments are clean, colorless and odorless. Leading waterborne preservatives approved for outdoor applications in the market today include Alkaline Copper Quat (ACQ), Copper Azole (CA) and Chromated Copper Arsenate (CCA).
Recent labeling changes mandated by the Environmental Protection Agency have removed CCA as a preservative of lumber products intended for general consumer use. ACQ and CA are replacing CCA in the outdoor consumer market, generally for the preservation of common lumber of one- to two-inches in thickness or small sawn posts, usually less than 5x5". Sold under a variety of trade names, ACQ and CA contain no arsenical or chromium compounds and provide the same resistance to decay and termite attack.
CCA Treatment Still EPA Approved for Saltwater Use
While ACQ and CA are effective in ground contact or freshwater applications, CCA still has an important role to play in harsh marine environments where wood is either immersed in saltwater (including brackish) or exposed to saltwater splash. That is why the EPA continues to approve the use of CCA for marine construction, as specified in the American Wood Preserver's Association Use Category Standard UC5 and Commodity Standard C18. Properly specified and installed, CCA-treated Southern Pine rejects destructive marine fungi and borers - the chemical treatment makes the wood an undesirable food source for these organisms. See a list of products that may continue to be treated with CCA here.
Marine specifiers will continue to select CCA treatment for structural components exposed to saltwater, such as round piles, sawn timbers and heavy dimension lumber used for cross bracing, pile caps and stringers. But with broad introduction of "environmentally friendly" ACQ and CA into the market, there are now alternatives to CCA for surface decking, railing and other components not exposed to salt water. Specifiers may now select economical ACA- or CA-treated Southern Pine decking as the "environmentally friendly" choice over costly and nonrenewable petrochemical-based composites.
Order or download the guide to Aquatic and Wetland Structures. To find a source of supply, go to the Product Locator.
Southern Pine Dock in Connecticut
In Stratford, Connecticut, a 79-year-old coal dock has been renovated and transformed into a public-access pier that is the nucleus for a new marina and shopping center. The facility is called Marina at the Dock.
Steve Sullivan of Sullivan Flotation says that wood was chosen for the marina docks because of its strength, durability and competitive cost. He adds that wood is easier to saw and fasten than plastic and that recycled plastic decking is much heavier than wood decking. Total cost of the new marina and floating docks was approximately $1 million.
Southern Pine plays key role in Canadian Dock System
Technomarine International is Canada's leading producer of floating dock systems, but one of their key materials comes from America's Southland. The company's unique dock system is fabricated with marine tempered aluminum alloy framing, moulded polyethylene floats and treated Southern Pine lumber decking.
A recent installation at the Landings Marina at Creg Quay is part of a phased-construction program over five years, representing an investment of some $600,000. Creg Quay is on the shores of Lake St. Francis, east of Montreal. The facility now has 176 slips and will soon be expanded to 400 slips. All utilizing treated Southern Pine.
Southern Pine Decking Costs 30% less than Plastic
Marco Island, Florida, combines exclusive upscale homes (average cost $1 million) with a rich history that spans centuries. It is the last barrier island to be developed in Florida. A new marina at the Key Marco Development accommodates 200 boats, with future expansion to include a fishing pier. Southern Pine provided higher strength and substantial savings over the cost of plastic decking.
Each slip is wired for a boat hoist and pump-out stations are available. Total project cost was about $700,000. Southern Pine decking is far stronger than competitive materials. Ronnie Edwards of Marine Lumber Supply says it would have been necessary to double the number of 3" x 10" stringers if plastic decking had been used, spacing them 12" on center, versus 24" on center. The use of plastic would have also increased the overall cost of the piers by 30%, Edwards notes.
Boathouses & Southern Pine gaining in Popularity
One of the best-known marine contractors on the North Carolina coast is D&B Marine Construction of Sneads Ferry. The company runs two construction crews year-round and specializes in docks, marinas, piers, seawalls & boathouses. D&B's primary construction material is pressure-treated Southern Pine lumber.
D&B reports that marine construction volume is growing each year, with boathouses becoming increasingly popular. The company recently completed four boathouses for waterfront homeowners off the Intercoastal Waterway near Surf City, North Carolina, each topped with a beautiful and fully functional sun deck.
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