Before treating the exterior timbers, you must first determine where the mildew is located, says Charis Babcock, brand manager for Sashco, Inc., which specializes in wood preservation and maintenance. She suggests dipping a cotton swab in household bleach and applying it to the affected area. “If it removes the mildew right away, it’s on the surface,” she explains. “If it removes it, but not for 30 seconds or more, it’s under the surface of the stain or finish.” To treat mildew that has accumulated on top of the wood stain, Babcock recommends washing the timbers with a sodium percarbonate cleaner. Sodium percarbonate dissolves mildew and helps treat any resultant discoloration.
If the mildew formed underneath the stain, it will require a more complex treatment. You will first need to remove the stain, then use a sodium percarbonate cleaner
to eliminate any remaining mildew.
Keep in mind that, when it comes to keeping your home in pristine shape, preventive steps are key. Babcock advises starting with a quality stain with mildewicides that will prevent moisture from seeping into the wood. For timbers at a higher risk of accumulating mildew, use a mildewicide additive in the finish as well.
Be sure to perform maintenance checks in the spring and fall
to test and clean the wood. If you find the timbers soaking up water, a touch-up may be necessary. Also remove any dirt, pollen, bird droppings or sap that may have accumulated on the timbers, as mildew spores can easily attach to these contaminants, says Babcock.
Finally, check for any cracks in the timbers. “Anything larger than an inch should be sealed with a high-quality wood-specific caulk,” she says. “Anything smaller than that should be thoroughly soaked with the stain or finish
. These little cracks can be highways for both moisture and insects, and keeping them sealed will prevent problems, as well as prolong the life of the stain or finish.”
See also Easy Spring Cleaning Products for Your Timber Home