What is Mold?
Mold is a general term for many types of fungus which reproduce by means of spores, making it similar to mushrooms and mildew. It typically grows in dark, humid areas where there is an abundance of moisture present because this is what it feeds off of. Over time, mold can develop on wood surfaces due to excess moisture being trapped underneath decking boards, etc. This happens because these materials are not designed to repel water like metal sheets, plastic surfaces, etc. Mold growth will eventually eat away at wooden decking if left untreated which will leave behind dark stains and cause the wood to rot out over time leading to severe damage to the decks.
Steps for Minimizing and Preventing Mold Growth on Decks
1. Proper Ventilation – Make sure your deck is not too enclosed with plants or other landscaping. This will create excess moisture which mold thrives off of. Make sure there are openings around railings to allow airflow, regardless of the deck is screened in. Also make sure you have good airflow throughout the exterior of your home by opening windows or using fans to circulate airflow into areas that are more enclosed, like underneath deck staircases, etc.
2. Grading & Drainage – Keep plant beds near decks graded away from the home instead of toward it to avoid excess water gathering underneath the decking area where mold loves moist conditions. It is also a great option to have an exterior French drain installed around your home if you are dealing with heavy amounts of rain on your property. This is especially useful for draining water away from any area of your house where it can pool up, like next to decks or underneath windows.
3. Washing – The more mold that has grown on the decking, the harder it will be to remove. Make sure you start by washing all loose material off of the surface. Then use an appropriate solution (look for one at Home Depot) and spray down the entire deck with a pressure washer set on low pressure. Take care to avoid hard angles in wooden boards as these areas are harder to clean properly. If you cannot get enough of the mold off with the pressure washer, you can also use a steel brush to help scrub off some of it.
4. Sealing – Make sure you apply an appropriate seal over the decking immediately after using the power washer. This will help prevent new mold from growing or re-growing in that area for at least one year. If your deck does not have a finish on it, look into getting one to deter fungi growth.
5. Other Options – If none of the above options are available or if you cannot afford new plantings around your home or French drains, there are other products on the market that may be able to keep mold away from decks and backyard areas for an extended period of time without having too much adverse effect on the environment. Look into products that are marketed as antimicrobial or mold-resistant for the best results.