There's no secret to deck maintenance. Clean it, repair it & protect it. But learning tricks the pros use can make the job go faster and the results last longer.
by Joe Hurst-Wajszczuk - From This Old House
Following are some techniques you can use to give an old deck a new lease on life, or to help maintain the look of a new one. A project like this can be done in two days, but it's best to spread the work over two weekends to ensure the wood is completely dry before you apply stain.
Begin by inspecting the entire deck. Pay special attention to any part of the deck that is in direct contact with the ground, such as the posts, stair stringers or joists that are at ground level. Graf uses a screwdriver to check for structural damage. "If you can sink the tip of a screwdriver into a post or joist, it means the you've got rot and it's time for a major renovation. Use a pry bar to pull damaged boards. Remove fasteners and lift the board straight up to avoid damaging adjacent boards.
If you need to rip any replacement decking, use a table saw. Ease the sawn edge using a router fitted with a 3/8" roundover bit. Also, inspect the deck-to-house connection. Screws and bolts can loosen and rust. Without the proper use of spacers and flashing, moisture can cause your band joist to rot. Tighten the fasteners that attach the deck to the house, look for any missing, bent or rusted flashing and carefully inspect inside and out for any telltale black stains that suggest moisture is working its way into your home.
Trim the replacement boards with a circular saw using adjacent boards as a cutting guide is faster and more accurate than measuring. Next, look for any cosmetic damage. For example, tap down any popped nails or consider replacing them with screws. Screws don't pop like nails. You want the new boards to match the rest of the deck. Carefully inspect railings and decking for loose wood. No one likes to catch a 2-in. -long splinter on the hand or foot.
A power washer is best for removing sun damaged wood fibers and for tackling scrub resistant stains. Here's the bad news: Every deck should have an annual cleaning. Assuming they have been maintained regularly, most decks can be revived with just a deck cleaner. Some products, like Thompson's Deck Wash ($10, 1 gal. covers 250 sq. ft.), you mix in a bucket and apply to the deck; others, like GE's Weathermate ($30, 1 gal. covers 500 sq. ft.), come in containers with integral applicators that you hook up to a garden hose. Once on the deck, most still require a stiff-bristle brush and a lot of elbow grease to work the mixture into the wood. Always wear eye protection and gloves when working with concentrated chemicals. You'll also want to protect nearby plants. The level of plant protection depends on the type and concentration of the chemicals you choose. For weak solutions and "plant-friendly" cleaners, you may need to only mist the plants before and after using cleaning. Powerful deck restorers can burn leaves on contact; in that case you should cover nearby plants with plastic sheeting.
Use a brush to work the cleaner into the wood fibers. The boards should be kept damp in order for the cleaning solution to work effectively. For tackling tough stains, use a pressure washer (about $70 a day), using a fan-type nozzle instead of a pinpoint nozzle that can dig into the wood. For removing the mildew, 1 part bleach to 2 parts water should be fed into into the intake hose on the washer. Go over the deck with a stiff-bristle brush, and then rinse. Allow the deck to dry thoroughly before staining.
Once all of the repairs have been made and the deck is clean, it's time to apply a protective finish. Clear finishes and transparent stains are fine for new wood, but for older decks, a semitransparent stain is recommended. The grain still shows through, but the pigment gives the old wood a clean, uniform color and helps the new wood blend in. The pigment also provides extra protection from the damaging effects of the sun and will last longer than clear finishes. Unlike paint, stain is absorbed by the wood and does not form a film on its surface, so it will not peel or chip.
A sprayer quickly lays the stain on the wood. To avoid making lap marks, maintain a wet edge and finish only a few boards at a time. Spraying is fast, and puts more stain on the wood than rolling or brushing. Most painters and homeowners are better off spraying on a generous coat of stain and then following up with a roller or brush to spread out puddles and work the finish into the wood.
Use a 2" brush to to take care of any drips, cut in around the finished posts and apply extra stain to exposed end grains. A wider brush can be used to work the stain into the wood in the field. It's highly recommended to start an inside corner and work your way out, applying the stain parallel to the deck boards. To avoid staining the nearby brick, use a small piece of cardboard as a spray shield; the brush provides even more control around deck railings and posts. A 700-sq.-ft. deck required about 5 gal. of stain — almost twice as much as the estimates indicated on the can. Old wood can get thirsty. On some decks, you'll need to apply two or three coats of stain in order to get a uniform finish. Subsequent coats should be applied while the first coat is still wet or they will not be absorbed into the wood. Stain won't peel, but it can wear away, especially in high-traffic areas. It's recommended to apply a fresh coat every other year. A clear water repellent can be applied between staining for extra protection.