Tip 15: Clean mildew off vinyl siding

Question: The following question came into our website: “We have had several neighbors ask about mildew on the outside of their home, on the plastic siding. Can you give some advice on this subject?”

Answer: Mildew, besides being unsightly, can also do permanent damage to your vinyl siding. Prolonged exposure to sunlight will bake the mildew into the siding, making it nearly impossible to remove.

First let’s positively identify the problem as mildew. Mildew is a gray or white powdery substance with black spots in it. If you wipe it with a cloth, it will smear on the siding. The test is to spray a small amount of 25% bleach solution in an inconspicuous location. If the substance disappears in a few minutes, it is probably mildew. If not, it is dirt, cobwebs, or a combination of the two.

One of three cleaning solutions can be used to remove mildew.

— 70% water and 30% white vinegar
— Simple Green
— 25% bleach and 75% water

You need to test these in an inconspicuous place on your house to make sure they do not darken, lighten, or otherwise mark your siding. This will also give you a way to select the solution that works best for you on your house. To be safe, put a tarp over any plants or bushes that might be harmed by the cleaning solution.

Once you have selected the preferred cleaning solution, you are ready to start. You will need a soft scrub brush mounted on a long handle. Eight feet should be long enough for most Sun City houses. Spray an area about ten feet by ten feet with a garden hose. Use the scrub brush to remove dirt on the siding and rinse. Spray your cleaning solution on the wet siding. Let it sit for 10-20 minutes to work on the mildew. Scrub the whole area and rinse. Wash from the bottom up and spray the rinse water downward and away from the vertical lap joints. As with washing a car, it is best to do this on a cloudy day so the cleaning solution does not dry on the siding. You can use a pressure washer, but set the pressure low, use a fan nozzle on the wand, and be careful not to force water into the joints.

If mildew is a continuing problem on your house, you should look for the cause. Is it forming around the dryer vent? Are the gutters malfunctioning? Is the lawn sprinkler putting water on your siding? If any of these conditions exist, corrections should be made or the mildew will return.

If all this sounds like too much work for you to do yourself, there are professionals who are in the business of removing mildew. Do not ignore a mildew problem, as it can permanently damage your siding.

If you have suggestions for future tips or have questions about maintenance around your home, submit them to ask.the.woodchucks@gmail.com.

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