A.  General Information
         You can add many years to the life of a deck with good construction techniques, high-quality materials, and regular maintenance. Still, even the most well-constructed deck has some weak spots: between the house and ledger, where posts are connected, boards with exposed end grain, railing joints, any notched joints, or joints in the decking. To avoid expensive repairs later on, you need to find and repair the problems early as possible. At least once a year, inspect your deck thoroughly. If you can, also inspect beneath the deck surface. If the deck is too close to the ground to crawl under, remove some decking boards to get a good look. Look for soft spots, indicating rot. Poke the wood with a screwdriver. If part of your deck is in worse shape than others, try to find the source of the problem before repairing. Water damage may be caused by faulty gutters or the accumulation of leaves or dirt. If you find potentially serious problems at the ledger, posts, beams, or joists, consult a professional. You can make most repairs yourself, but some are complicated projects.

B.  Check Ledger, Posts, Beams, and Joists
         The connection between the deck and the house is very critical. Check that flashing is in good condition. Use a probe to inspect for water damage on the ledger. Check for fungi, blue or black stains, and little piles of sawdust indicating termites or carpenter ants. Tighten all fasteners.

Check the posts very carefully at the ground line and at the top. Use a probe to inspect for rot by sticking it into various parts of the post and comparing the ease of penetration. Inspect and secure the post's connection with the foundation.

C.  Check Decking from Below if Possible
         If you can go under your deck, put on old clothes, and bring a flashlight and a screwdriver with you. Poke the undersides of decking boards, all around the ledger, posts, stringers, and treads, and in any other joints and crevices.

Some loose decking might only need retightening of the fasteners. Tighten the ones you can and mark the ones that need to be replaced. If the decking is damaged, remove it and install new boards.

D.  Check Railings
         Railings, and especially stair rails, are very important since they have to withstand extra strain. Inspect posts for damage and make sure all fasteners are secure and tight. Look at the ends of all rails for water damage. Replace damaged balusters. Decking boards split at the ends will usually continue to separate along their length. You can try to cut the boards flush with the joists and seal the cut ends, but it would probably be better to replace split boards with new ones. For internal cracks, sand the surface and apply several coats of sealer.

E.  Pressure Washing
         Any dirt, leaves, or other natural debris that get caught between the decking or in other crevices can hold moisture for weeks. That can easily cause rot but can easily be prevented by cleaning regularly. One way to clean out crevices is by pressure-washing.

It might be hard to realize when is a good time to clean or refinish your deck, so, to be on top of it you can make a calendar. Little things can have big results. Cleaning gives a drab deck a fresh new look and you'll be surprised how much bigger a clean deck looks. You should sweep the surface once a week and if the weather requires it. Once a month you should scrub the deck with warm water and a mild detergent. If simple washing doesn't get it clean enough, or if you want to make the color of the deck lighter, buy a deck cleaning product. If the wood is dirty and weathered, clean it with a solution of oxalic acid and water. Scrub an area with a stiff natural-bristle brush, rinse, allow it to dry, and repeat if needed. Oxalic acid is extremely caustic so wear protective clothing. If you want to clear away all dirt, debris stuck in joints, or loose paint all at once, the best way is to rent a power washer with 1200 psi pressure. Clean the deck with a fan-tip nozzle so you won't damage the surface. If you use a high-pressure power washer improperly, it can splinter and gouge the surface of lumber. Pressure-treated lumber rated for ground contact should resist insect infestation, but redwood and cedar aren't guaranteed to be free of pests, like termites and wood-borers. They like to eat in the dark, so they tunnel along the grain lines inside the wood where you can't see them. That means that by the time you notice the damage, it's too late. If you see small piles of fine sawdust at the edge of a board or tunnels running inside a board, call a professional exterminator.

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