How to Kill Mold & Fungus on Wood

Updated February 21, 2017

Wood objects are highly vulnerable to the effects of mould and other fungi because wood absorbs and contains moisture. If you begin to notice signs of fungus on your fence, deck, beams, furniture or other wood objects, you will need to take steps to remove the spores immediately. If you allow the fungus to remain, the problem may spread to other areas, damage the wood and even pose potential health risks to you or members of your family.

Place wood objects outside in the sun to dry. If the object is immovable and already in the path of sunlight, such as wooden decking, remove any obstacles to sunlight, which may include shrubbery, furniture or assorted items. For immovable objects not exposed to sunlight, dry them as thoroughly as possible using heat. A dehumidifier can effectively dry dampened wood, as can a space heater or other commercial heating device.

Pour a few ounces of household bleach into a spray bottle and dilute with water. Use four times the amount of water -- or four parts water to one part bleach -- in order to prevent bleaching your wood while still reaping the mould-fighting benefits. Spray your diluted bleach gently onto a soft cloth. Moisten, but do not saturate, the cloth.

Wipe down your entire wood surface using your cloth. Make sure to scrub between cracks and small crevices, and try not to miss anything. Mold and other fungus spores are microscopic, and may exist even where you do not see them. If you allow spores to remain, they can become active at a later time when exposed to high relative humidity. Allow the bleach to remain on your wood for at least 15 minutes.

Wipe down your wood with a second cloth, dampened only with warm water. This will remove the bleach from the surface of the wood and prevent permanent discolouration. Allow your wood to remain in the sunlight or near a source of heat until completely dry.

Sand your wood if mould continues to recur. In some cases, moisture becomes set deep within the surface of the wood, making total moisture removal a difficult or even impossible task. Sanding your wood will release some of the moisture and remove the cracks and crevices where moisture hides. Using a piece of sand paper, rub firmly -- always moving in the direction of the wood grain -- until your wood feels completely smooth. Place your wood in the sun to dry.


To prevent mould from recurring on your wood fencing, decking and other outdoor objects, consider repainting the surface using a mildew resistant paint, available at paint stores.

Things You'll Need

  • Space heater
  • Dehumidifier
  • Bleach
  • Spray bottle
  • Soft cloths
  • Mildew resistant paint
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