Marine Construction

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. For a list of products that may continue to be treated with CCA, go to www.southernpine.com

Marine specifiers will continue to select CCA-treated 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 in contact with the public. Specifiers may now select economical ACA- or CA-treated Southern Pine decking as the "environmentally friendly" choice over costly and nonrenewable petrochemical-based composites.

For more detailed information on marine construction, refer to the Marine Construction Manual available at www.southernpine.com. To find a source of supply for pressure-treated Southern Pine, use the Product Locator at www.southernpine.com.

Timber Bridges & Walkways

Southern Pine Lumber has been used for bridges, walkways, and boardwalks for hundreds of years. The great Atlantic City Boardwalk was built with preservatively treated Southern Pine lumber in 1867. To meet today's environmental requirements, designers are following a trend to span wetland areas with timber bridges and elevated wood boardwalks.

Industry standards have been developed to insure long-term performance of treated wood. New advances in preservative treatments, and in design and construction techniques, make lumber a cost-effective construction material for bridge applications. See typical examples below.

For more detailed information, refer to the Pedestrian Bridges and Walkways design and construction guide available at www.southernpine.com. To find a source of supply, use the Product Locator at www.southernpine.com.

Walkway Construction

Elevated walkways are an excellent alternative for wetland filling and the associated negative environmental impacts. Meandering elevated walkways through forests, wildlife sanctuaries and nature preserves offer pedestrians and cyclists opportunities to view environmentally sensitive areas from a new perspective, while allowing minimal impact on the natural activity of such an area.

Glued Laminated Pedestrian Walkways

Structural glued laminated timber (glulam) is a popular construction material that is frequently used for pedestrian bridges and walkways. North American architects engineers, designers and contractors have been specifying glulam for more than half a century. The demand for Southern Pine glued laminated timber continues to increase because of its high strength, natural beauty, competitive cost, dimensional stability and is readily available in a large range of sizes and shapes.

Glued laminated timber can be easily preservative-treated for wet service conditions and can satisfy virtually any design while providing fast erection and competitive in-place costs, hence its growing acceptance and use in pedestrian bridges and walkways.

Golf Cart and Small Vehicular Bridge Applications

Golf courses around the country are experiencing genuine success by expanding and incorporating elevated cart paths and bridges made of preservatively treated Southern Pine lumber. Club developers like the timber cart paths and bridges because their natural look blends in with the environment and they eliminate the need for fill, thus providing for easier access to obtaining environmental permits.