The biggest risk to wood siding is moisture, which will lead to rotting, insect infestations, mildew; mold; paint peeling, etc.
Wood siding expands and contracts with normal changes in humidity and temperature. These fluctuations cause paint to chip and crack, and cause caulked seams to deteriorate around windows, doors, and corners. And because the south and west sides of your home receive the most sun, they will wear faster than the north and east sides, and your siding will need repairs and re-finishing more often on these sides of your home.
It is therefore important that at least once a year you should inspect your wood siding. Inspect your siding for any possible places where water can penetrate or get under the boards: joints with cracked caulking; missing flashing; cracked boards; chipped or peeling paint; open nail holes; and around trim and light fixtures.
Your wood siding must be properly finished with paint, stain, or clear sealer. Left unprotected, it’s susceptible to rot and decay caused by moisture.
But in addition to being properly finished, there are other things you should do to protect your wood siding. For example, make sure that any soil is at least 8 inches below the bottom of your wood siding, to prevent moisture and insects from infiltrating your wood. And be sure that no bushes, tree branches, shrubbery, etc. are touching your wood siding. These can scratch your siding and create opportunities for insects and moisture to attack your wood. You should always have about 1-2 feet between your house and any plant materials, including crawling vines.
And take care that any lawn sprinklers do not spray water onto your wood siding, especially sprinkler heads which point upwards and can spray water under the edges of your wood siding, Masonry or Brick. Over time miss-adjusted sprinklers can create an avenue for water intrusion into your home or building, which if nothing else can lead to a maintenance nightmare. Check the coverage of your sprinkler heads once a month and adjust as necessary to prevent a large repair bill. A little maintenance now can save you $$. And further about your lawn, when mowing your grass, be sure that the mower discharge faces away from your house, so that sticks and stones thrown from the mower do not fly against and damage your siding.
Never let children throw balls against your siding. And if you have problems with wood peckers, then placing a wind chime nearby can often help keep them away.
You will also want to make sure that your attic has proper ventilation, and maintain your indoor humidity below 65%. As high humidity from these areas can cause moisture to get behind your wood siding. And if you are in a region that is prone to ice damming, you should consider adding roof heat tracing wires, to prevent ice build-ups which can cause water to infiltrate behind your wood siding.