How to Clean a Cedar Shake Roof

A cedar shake roof keeps the charm of your Cape Cod, timber frame, or craftsman style home intact. There are two common challenges with cedar shake roofs, however--both affecting the color of the shakes or tapers, as they are also called.

Green Growth on Cedar Shakes

Moss growing on cedar shakes poses no real threat. But if you just don't like it, here are a few ways to eliminate it and keep it from coming back:

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• Bleach and water solution: Spray some bleach diluted with water on the moss, then spray with clean water.
• Zinc Sulfate: Found in many herbicides, it can kill off moss and keep it from coming back. Spay it once to kill it, then affix strips of zinc along the rows of shakes. When water runs across them, the zinc is spread about to stop the moss from returning.

Cedar Shake Grey Tinges

Unfortunately, that rustic hue isn't always sun-baked age. It can actually be black mold and mildew. Luckily, it can be removed:

• Trisodium phosphate (TSP) or bleach and water: These household cleaners work well at killing mold, but can produce the unwanted effect of bleaching the wood.
• Peroxide-based cleaners: If your cedar shake roof is treated, you might consider a commercial cedar cleaner like Cedar Wash. It sprays on easily and washes away the black mold and grey hue. If your roof is not treated, do not use cedar cleaners, as they can further embed the dirt into the cedar shakes.

Pressure Washer Tips for Cedar Shake Roofs

• Test the condition of your wood--if your cedar shakes are falling down with every rain, then any pressure washer might create more damage than help.
• Check the pressure on your hand. If it hurts, it's too much pressure.

Following the suggestions above can keep your cedar shake roof looking clean and attractive throughout its lifetime.