How do I get mold and mildew off of my Trex fence?

WHY DOES MOLD GROW ON MY FENCE

Mold and mildew are microscopic fungi that often grow on surfaces where conditions are right and organic mass (microscopic organic particles that contain cellulose like pollen or decaying plant debris) is available to consume. Mildew is a particular type of mold so for purposes of this topic, we'll group these types of fungal growth under the generic term "mold." 

Mold requires a warmer, humid climate to thrive. Shady spots with high moisture content in the air are areas that are particularly susceptible to growth. Organic particles can exist in water, so water that is sitting on the surface of the material can give mold a sustainable source of food and humidity to grow. For this reason, we encourage customers to open their shipment as soon as possible after orders arrive to reduce the risk of giving mold time to take hold. 

HOW TO CLEAN MOLD OFF MY FENCE

If the area where your fence is installed is prone to providing an environment that's friendly to mold growth, you will need to perform periodic maintenance to keep the problem under control. While you are removing the existing mold, take measures to clean up the space around the fence to remove the mold's food sources and give the space as much circulation and sunlight as possible by cutting back overgrowth. 

To get mold or mildew off your fence, you can employ a variety of methods. These organisms feed on the build up of microscopic organic materials such as grass clippings or pollen that settle on and attaches itself to the fence. The first thing to evaluate is what you can do to change the environment where the mold is growing to reduce or eliminate regrowth. That may mean trimming back bushes or cleaning up organic debris that has built up around the fence on a regular basis. 

Sunlight is a natural way of helping to control mold growth. The UV rays in sunlight disrupts the reproduction of mold spores. This can be helpful for customers that have mold growth on materials prior to installation. For example, exposing a gate for a few days to direct sunlight can kill mold, making it easier to clean up and wash off. However, sunlight cannot completely eliminate spores alone. It simply deactivates spore production on the surface, so if the product is then installed in an environment that has conditions for mold growth, it will reactivate.

Once you've cleaned up the affected environment, start with a simple step of cleaning the fence with soapy water and a soft scrub brush.  Mold will grow into pores on the fence surface so scrubbing may take some effort but you will want to do as thorough a cleaning job as possible to reduce the chance of mold coming back. 

If a simple cleanup with soapy water and a soft brush is not effective, there are more aggressive options. Before applying any potential solution, test a small area of your fence to see if it gets the mold off with acceptable results. 

• Try a white vinegar solution to kill the mold. Fill a spray bottle with equal parts water and white vinegar to create a solution. Spray the solution on the fence and use a soft bristle brush to scrub in the vinegar. Let the solution sit on the fence for an hour. Hose off the solution and mold once you are done scrubbing. Important note: since the acid in vinegar can be harmful to sensitive plants, spray your plants with water before and after applying the solution. For additional protection, consider covering the space next to your fence with plastic sheetsbefore performing the cleaning. 
• The white vinegar solution is usually effective in eliminating the organic growth, but if it doesn't produce the results you need, contact your local garden supply or home improvement stores and ask for help recommending a biocide that is specific to mold and mildew control. Follow the directions for application and safety. 
• Even after the organic growth has been killed off, staining could remain. The impact of the staining can be reduced by using cleansers. One product that is particularly effective is Spray & Forget Deck Cleaner. There are even stronger cleansers for particularly tough stains. These are usually products containing some level of sodium hypochlorite (bleach) and detergent. To clean and even out discoloration, an oxalic acid solution (also called deck cleaner or deck brightener) can be used. Be aware that because the solution contains bleach, it will lighten the material. Here is information on the application of an oxalic acid solution. Because Trex Fencing is made of the same material as Trex traditional decking, the application would be the same.

View Trex's Mold Technical Bulletin for additional details on removing mold growth on your Trex products. 

Future considerations

Mold and mildew prefer moist, warm, environments and tend to thrive where they do not have direct sunlight exposure throughout most of the day. While shade may be a priority in your backyard, if you are in an area that is susceptible to mold, consider opening up the space to get more light.

Maintaining a cleaner environment and improving airflow around the fence is important to reduce the chance of mold spores taking hold. While Trex itself doesn't require painting or staining, and it won't rot or be damaged by mold growth, there are health concerns to consider. If you have mold growing in your environment, including on your fence, reducing its presence is beneficial to your health, given that mold can trigger respiratory problems.

Looking for more ideas on cleaning your Trex Fence? View the Care & Cleaning Guide on our website for help on a variety of other maintenance needs.