How to Clean Mildew on a Shed

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Things You'll Need

  • Bleach

  • Water

  • Measuring cups

  • 2 1-gallon buckets

  • Sponge

  • Vinegar

Mildew on the bark of a tree.

Mildew produces a green discoloration on surfaces frequently exposed to water. It commonly infects outdoor surfaces, such as the siding and roofs on sheds. While a natural occurrence, mildew is less than pleasant to look at and can even rub onto your clothes if you come into contact with a mildew-covered surface. Luckily, mildew is easy to remove from any type of siding or roof on your outdoor shed.


Step 1

Mix up a solution of bleach and water to use for cleaning your shed. For painted wood sheds, use a mixture of 3/4 cup bleach into a gallon bucket of water. For unpainted wood, you can use a stronger solution of 1 cup of bleach for every 3 cups of water. In both cases, fill a second bucket with plain water.

Step 2

Dampen the sponge in the bleach and water solution and scrub the mold and mildew off the wood shed siding. Scrub gently and avoid squeezing too much water onto the wood siding.

Step 3

Rinse the sponge in the plain water bucket and use the plain water and sponge to rinse off the wood shed before the diluted bleach causes discoloration of the shed wood or paint.

Vinyl Siding

Step 1

Create a cleaning solution to remove mildew from your vinyl siding. In a gallon bucket combine 3 cups of vinegar and 7 cups water.

Step 2

Dip a sponge in the water and vinegar mixture and avoid wringing out the sponge.

Step 3

Wipe the over-saturated sponge across the vinyl siding on your shed. Wipe away spots of mildew, allowing the sponge to drip down the siding.

Aluminum or Metal Siding

Step 1

Create a cleaning solution from 1 cup of bleach combined with 3 cups of water. Mix the solution in a gallon bucket of water. Fill a second bucket with plain water.

Step 2

Use a sponge dampened in the solution to wipe away the mildew on the aluminum or metal shed siding.

Step 3

Rinse the sponge thoroughly with running water. Then use the clean sponge to rinse the shed siding with plain water to remove traces of the mildew and bleach.


Clean the mildew on a dry, sunny day so the rinse water dries rapidly off the shed siding.

references & resources

Penny Porter

Penny Porter is a full-time professional writer and a contributor to "Kraze" magazine. She is pursuing a bachelor's degree in journalism at Eastern Kentucky University in Richmond, Kentucky.