Mildew, algae, and mold can all leave behind ugly greenish-black stains on a wooden fence. In many cases, you can remove the stains and save the fence. The following guide will help you determine when to clean and when to replace, along with providing you instructions for removing and preventing the stains.
Clean or Replace?
Algae and mildew stains are caused by moisture, since algae and mildew only grow in damp environments. Too much moisture can also cause the wooden fence boards to rot. Before attempting to clean the board, poke it firmly (but not too firmly!) with a screwdriver. If the wood gives beneath the screwdriver, the boards have begun to rot. Each rotten board will need removal and replacement. Boards that are firm are stained but in otherwise good condition, so they can be saved.
Gather Your Supplies
The right tools are vital for getting the fence clean. Begin with a trisodium phosphate cleaner, which will both kill the algae and mold and remove the stains. This usually comes as a concentrate, which you will need to dilute in water according to the package instructions. You will also need a stiff bristled scrub brush, gloves and protective eyewear, as well as a spray bottle to place the cleaner in. You should also have a bucket of warm water nearby. You may also want to spread a tarp over the ground in front of the fence so the cleaner doesn't harm the grass or plants.
The simplest way to clean the fence is to soak a small area with the cleaner and allow it to soak in for a few minutes before scrubbing down the fence with the brush. Then, scrub a second time with just the warm water. Repeat the process until the entire area is cleaned. For badly stained fences, you may need to repeat the process several times.
Prevent Future Issues
The final step is to seal your fence. You may want to smooth any rough areas first with sandpaper – start with a medium grit and finish with a fine grit to make sure it is smooth. Then, apply a weather sealer of your choice. Generally, you should reseal every couple of years or when water no longer beads up on the fence boards. If light staining remains, you can opt to paint the fence instead. A wood stain is another option, but sometimes a mildew stain still shows through the translucent wood stain. Contact a fencing contractor like those at American Secured Fence for more information.