Roofs have shingles, walls have siding and even most pools have covers.
But decks are left naked -- hot and cold, wet and dry, snow-covered and otherwise subject to drying winds and the sun's ultraviolet rays.
Without their protective bark, even weather-hardy redwood, cedar and pressure-treated lumber can use some basic repair and improvement come spring.
Cleaning
Proprietary mixes don't seem to clean any better than a basic brew of up to half household bleach and half water. (It and most cleaners are strong enough to damage unprotected plantings and also carry handling cautions.) Scrubbing works well against mold and other discoloration, although it's one more muscle-power job that's given way to power tools -- in this case, pressure washers.
The spray from a garden hose with a pressure of about 50 psi might help. But pressure washers at 1,000 psi and up scrub harder and dig deeper. That's the catch. More pressure easily blasts away dirt and grime but may also erode the surface. High-velocity water jets tend to remove the softwood sections of deck boards, leaving uncomfortable and potentially dangerous ridges of harder grain.
Whether you use your own pressure washer, rent one, or hire a contractor, it's wise to start by testing a board at the lowest setting. Then the pressure can be dialed up gradually to increase cleaning power without damaging the deck.
You can also experiment with small amounts of different cleaning solutions. Then fill the mix container supplied on most pressure washers to combine the cleaner with the high-powered water flow.
Nail heads and splinters
Weather works wood, often producing enough stress to split edges and raise nail heads. So before you encounter them in bare feet, check the surface by sweeping the back of a metal rake across the surface. Telltale dings will reveal the danger points.
Cut away splinters at the head of the split and sand remaining rough edges even though this takes little chunks out of the boards. Gluing a split may work for a while and make the board look better. But glue can give way in hot weather when people are in bare feet.
Instead of pounding down nail heads (another temporary fix), pull them and drive screws at least as long as the nails. Screws provide more holding power against twisting boards and won't pop as the deck boards react to increasing heat and humidity.
Thinking about a new deck? Consider hidden fasteners. They're more time-consuming to install but leave no holes or nail-popping heads exposed. But a system like this cries for wood that's worth a hidden-fastener finish: cedar, redwood, maybe teak, mahogany or Ipe, an incredibly hard South American wood sometimes referred to by brand names such as Pau Lope and Iron Woods.
Flattening and straightening boards
The grain of some boards gradually curls in the weather -- along the board, causing a warp, or across the board, causing a cup. You can't see this twisting tendency when you buy lumber, though unusually heavy (water-laden) boards tend to shift more than most.
Both cups and warps can make a deck look a little ragged. But cupping also traps surface water that gradually seeps into nail holes and fosters rot. Some people flip a cupped board, then (after some cleanup) flatten the now convex shape by driving screws through the high point. This can work on wide boards such as 2-by-6s but rarely on narrower 2-by-4s.
Screws also work better than nails when it comes to straightening long boards. But first use pry bars and clamps to pull a bent board into place, and then screws to secure it. If you rely on screws to do the pulling, the heads may tear through the surface or pull out of the joists below.
If more than one screw is needed (and maybe large ones), you may not want to see the heads. In that case, drill a shallow hole, a countersink, set the screw below the surface and cover it with a glued wood plug.
Resealing
Once a deck is repaired and cleaned, sealing will protect the upgrade and refresh the appearance by unifying the deck color. Don't paint.
Of course it looks good at first, the way paint renews siding. But you don't walk on siding.
If deck boards are bleached to different shades of light brown and dull gray, consider coating with a semi-transparent penetrating oil stain that contains a UV inhibitor. (Some oil finishes use latex emulsifiers allowing soap and water cleanup.) Start by screening plantings, siding and nearby concrete, and prime any new wood or areas that have been planed or sanded. Then use a well-loaded brush to coat edges and a heavy-napped roller to cover open areas. Work quickly to keep a wet edge and avoid overlapping, which can create darker stripes in the deck.
The real trick is matching this project to the weather forecast.
Application guidelines vary by manufacturer, but too much direct sun and any amount of rain can cause problems. The best bet: a few clear hours for the stain to penetrate and a few clear days for it to cure.
