Seaworthy: It takes special materials and techniques to construct decks that will resist conditions along a seashore. Many of these practices also can help toughen decks built inland.
Harry Whitver Seaworthy: It takes special materials and techniques to construct decks that will resist conditions along a seashore. Many of these practices also can help toughen decks built inland.

How do you build a deck that will stand up to some of the worst weather nature has to offer? To find out, we interviewed three builders who build on the beach. Their approaches are designed to protect the deck structure from wind and water damage and to keep finishes looking good over time. Given their environs, much of what they do also should work for you, too.

Peter Kroll of Cape Painting & Carpentry builds on Cape Cod, Mass. He prefers jobs where an architect is involved (“the more minds on the project, the better the result”) but regardless of design, he makes it a point to always overbuild–that is, go above code-mandated structural standards.

The work starts below ground level where, to resist wind uplift, the best coastal builders spec deeper, heavier concrete footings than required. For instance, Kroll uses mushroom footings rather than standard sonotubes. Beefed-up framing is also preferred: 4x6s where 4x4 posts are called for, and 2x10 rather than 2x8 joists.

When actually building on the beach, conventional footings may not be adequate: wet sand can act more like water than sand, which is why some raised decks are built on piles driven deep. In some cases, it’s acceptable to support the corners on piles and put concrete piers between them. While corner posts typically bear less weight than do middle posts, wind resistance must be taken into account.

Secure Anchors A strong deck also needs to resist being torn apart by hurricane-force winds. That means taking steps to securely anchor the frame and tie its pieces together.

Most connections are made with hardware rather than nails. If a beam bears directly on a concrete pier, that means embedding a metal strap in the pier and wrapping it over the beams; where a post is used, the post base must be securely embedded in the footing. You would also strap the beam to the post. All joists are supported by metal hangers, while hurricane clips and 1 1/2-inch metal straps connect posts to beams and beam to joists. Builder Eric Borden of Toms River, N.J., says that large decks have so many metal hangers it’s no longer sufficient to list them as an allowance on the estimate. “They now require their own line item,” he says.

Good hardware includes flashings. Kroll protects deck ledgers with lead-coated copper flashing rather than aluminum, and he leaves an air space so the wood can dry out.

What type of fastener to use depends on where you build. Galvanized is fine inland, but on the beach it may not be the best choice. “Today’s galvanized fasteners are terrible,” says Kroll, who recently replaced a set of steps built in the 1990s whose galvanized fasteners had rusted through. That’s why much of the hardware he uses, from the hurricane straps to the joist hangers, is stainless steel. They cost 20% to 30% more than galvanized, but he thinks it a wise investment for his customers and his reputation. He prefers #304 grade stainless hardware, which has the highest rust resistance because of its added nickel content.

Where galvanized nails are unavoidable, Kroll recommends hand nailing. “We never use nail guns on exterior decks because the coating on the nail tends to tear out,” he says. “In a salt environment, corrosion then quickly sets in.”

Good Looks Matter Long-term durability also includes aesthetics. Although problems with staining and mold in first-generation composites soured some builders on them, the technology has come a long way. Cape May, N.J., builder Smokey Saduk has had good luck with capped composites, but he says some scratch easily.

Among natural wood species, Ipe (Brazilian walnut) is one of the most popular because it stands up well to traffic and weathers to an attractive silver gray. “We’ve had ipe decks in place for years and haven’t had to do any repairs,” says Borden. However he makes sure that customers understand how the wood will weather. “I show them some weathered samples so they know how it will look in two years,” he says. “They need to know that a wood deck isn’t going to age like an interior floor.”

Less costly alternatives also can hold up to the elements. Kroll finds a vertical grain fir surface will last 20 years. Saduk likes mahogany.

Hide the Fasteners The contractors we talked to all preferred hidden fastener systems, in particular Deckmaster, EbTy, and Tiger Claw.

With the Deckmaster system, a metal bracket is fastened to the top edge of the joists before the decking is installed. The installers then lay the deck boards in place and drive screws through the bracket up into the underside of the boards. Saduk likes this system but finds it labor-intensive.

Tiger Claw relies on 3-inch-long stainless steel fasteners. The installer drives the fastener’s pronged edge into the edge of the deck board, then screws the fastener into the joist.

EbTy uses polypropylene biscuits installed between the deck boards at each joist. It’s about as labor-intensive as Deckmaster, but the installer can do all the work from above. The installer uses a biscuit joiner to kerf the edge, then slips the biscuit into the kerf and screws it into the top of the joist.

Says Borden: “It’s easy once you’re used to it, but getting set up with biscuits and learning to use them is time-consuming and wouldn’t be worthwhile for a small deck.” Some composite manufacturers have boards whose edges have been pre-grooved. “Our supplier will now add grooves to ipe and mahogany,” adds Saduk.