The Key Ingredients That Will Make Your Deck Last (almost) Forever

By Author: Blue Star Carpentry
Total Articles: 35
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Decking: The floor bears the brunt of rot on decks. Because deck boards lie flat, water collects in cracks and knots and soaks into the end grain—especially at splices. Because these areas stay wet for long periods of time, they are the most vulnerable to decay. Although we used Trex for the decking, we chose rough-sawn cedar lumber for the privacy wall, planter trim and other exposed wood to give the project a more natural, tactile character. Because these items are largely vertical, they can be made of wood and will last a very long time.

Lumber: The wood for all the above-ground framing is .40-grade pressure-treated lumber, which will last for decades without any maintenance. Posts and planter framing that are underground call for foundation-grade .60-treated lumber, the same material used for wood foundations. Foundation-grade material may be a special-order item in your part of the country, but most lumberyards can get it for you.

Hardware: Plan on spending a few extra dollars to get quality hardware designed for outside use. That means using double-hot-dipped galvanized nails or, better yet, stainless steel ...
... nails for all nailing, and exterior-rated joist hanger nails. You can also use special screws designed for composite decking or buy hidden fasteners designed for decking, though these get expensive. Install drip cap above the ledger and behind the siding (see Photo 2). Don't scrimp on hardware; remember that for the first time ever, the structure could outlast the hardware.

Design: Take pains to plan your deck for the long term. Think far into the future to get the size and shape right. Think in terms of a room addition more than a deck. We hired an architect and spent $500, a sum that bought us a site visit, a couple of preliminary drawings and final plans. He had numerous suggestions and ideas we wouldn't have thought of. With the design fee only 6 percent of the total project, it was a bargain.

Footings: Make sure your footings are deep and wide enough for your climate. When you take your plans in to get a building permit, your inspector will let you know about the local requirements. Here in Minnesota, that means 42-in. deep footings, but we went 48 in. to ensure that the deck would be able to handle the next ice age.

Structure: Build with shorter spans, narrower spacing and heavier materials than you would for a normal, wood deck. Our deck spans called for 2x10 beams and 2x8 joists, but we spent about extra and upsized the structural members to 2x12 beams and 2x10 joists to give a more beefy, permanent feel to what we expect will be an outside living room.