The biggest risk to wood cladding is moisture, which will lead to rotting, insect infestations, mildew; mould; paint peeling, etc. This article covers tips for protecting, cleaning, power washing, repairing, and painting your home’s wood cladding.
Wood cladding 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 cladding. Inspect your cladding 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.
PROTECTING
Your wood cladding must be properly finished with paint, stain, or clear sealer. Left unprotected, it’s susceptible to rot and decay caused by moisture (helpful accessory: wood paints and seals).
But in addition to being properly finished, there are other things you should do to protect your wood cladding. For example, make sure that any soil is at least 150mm below the bottom of your wood cladding, 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 meter between your house and any plant materials, including crawling vines.
Take care that any lawn sprinklers do not spray water onto your wood cladding, especially sprinkler heads that point upwards and can spray water under the edges of your wood cladding. 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 cladding. And if you have problems with birds, then placing a wind chime nearby can often help keep them away.
You will also want to make sure that your roof space has proper ventilation and maintain your indoor humidity below 65% (helpful accessory: indoor humidity monitors). High humidity from these areas can cause moisture to get behind your wood cladding.
CLEANING
Dirt is the most common cause of discolouration on wood cladding. You should clean dirt from your cladding using warm, soapy water and a soft-bristled brush. Frequently cleaning off dirt and mildew will help your wood cladding last longer. When cleaning your wood cladding, work in small sections and always start at the top and work your way down. Be sure to rinse your cleaning solution off the siding before it dries.
Before washing your wood cladding, be sure to: turn off power to any outside lights or outlets that may get wet; ensure that all windows are closed tightly; spray away from doors and windows; and if you have shrubbery or flowers nearby, make sure you cover them with plastic so no cleaning solution drips on them.
Natural wood cladding that has been discoloured with age can be restored to its original colour by applying a wood cleaner or brightener. These products often are intended for use on wood decks, but they work well on natural wood siding.
Mildew appears on the wood cladding as black spotty stains. Dab the area with a little diluted bleach, and if the black disappears, then it’s mildew. To clean mildew off of your wood siding, use a solution of one part bleach to four parts water. Scrub the areas with a soft-bristled, long-handled brush. Be sure to wear eye and skin protection, and protect plants from splashes. Rinse thoroughly with clean water. Depending on your type of wood and paint or stain, you may want to consider adding a mildewcide to help prevent mildew from returning.
Rust stains often appear as dark black splotches and vertical streaks. They’re usually caused by a nail or screw that isn’t galvanized. To remove the stain, dissolve 4 oz. oxalic acid in 1 cup of warm water. Apply the mixture to the stain and gently scrub with a soft bristle brush. Rinse thoroughly with water. Wear eye protection and acid-proof gloves, and avoid splashing the mixture onto adjacent surfaces.
POWER WASHING
You must be extremely careful when using a power washer on your wood cladding. The force of the water can strip paint, gouge softwoods, loosen caulk, and drive moisture into even painted surfaces.
When using a power washer, avoid aiming it upward, as this will drive moisture under your wood cladding. Always start the spraying action with the sprayer pointed away from the surface, then slowly begin to point the tip towards your cladding, until the pressure appears to be the correct strength. Never get closer than 300mm from the cladding or you may damage it. Use both hands when using a power washer, and never use it while on a ladder. And do not point it at windows.
When power washing, go the full length of the board and not up and down from board to board. Going from board to board causes a patchwork effect that will be unsightly and difficult to correct.
And finally, never power wash your house if you suspect that it may be painted with lead paint.
REPAIRING
Finish any necessary repairs before cleaning or painting your wood cladding. If you find problems with your wood cladding or caulking, they should be repaired as soon as possible, as water penetration damage can spread very rapidly.
If a cladding board is only slightly warped, it can usually be repaired by driving rust-resistant screws through the boards and into the underlying studs. Be sure to countersink the holes, fill them with putty and then paint. Significantly warped boards, however, may require removal and be sanded down with sandpaper, before they can be flattened further down with screws.
If there are holes you need to repair in your wood siding and they are deep, then you should fill the holes in stages, allowing each stage to dry completely before adding the next layer of fill. Split boards can be repaired by opening the split, applying waterproof glue and then clamping or screwing the two pieces back together (see types, costs, and reviews of water-resistant wood glues). If screwed together, then rust-resistant screws should be used.
When repairing the caulking on your cladding, use a colour-matched exterior caulk and apply it during dry days with temperatures over 15 degrees for maximum adhesion (helpful accessory: wood caulks).
PAINTING
Wood cladding typically needs to be painted every five years and treated or stained every three years, to ensure that it is properly protecting your wood. Choose a product that works best with your home’s particular wood and climate. Better quality paints and stains that last longer are good value, versus cheaper products that don’t last as long (helpful accessory: wood paints). How long your paint or stain will last for your wood cladding will depend on the quality of the surface preparation, the coating material, the type of siding, and the climate. Staining of your wood cladding should be done in accordance with your particular type of wood, and the manufacturer’s recommendation for the stain or clear sealer that you are using. Paint your house with lighter colours to reflect more of the sun’s heat if you live in a hotter climate, but darker-coloured if you live in a colder climate.
Before you paint your wood cladding, all dirt and paint chips should be removed using a wire brush or scraper. The surface should be clean and smooth, and if there are loose fibres, sandpaper should be used to smooth these areas. Dust the surface before applying a primer. Allow the primer to dry completely, and then apply several thin coats of paint (see types, costs, and reviews of wood primers). Never apply paint or stain over mildewed areas, as this will cause blistering and discolouration.
