Cedar shingles and cedar shake siding offer a beautiful, natural finish for any home and cedar products will provide protection for the home for decades. Over time, natural wood surfaces can become dirty from pollutants in the air as well as by attracting mildew and algae to grow on the surfaces. While most of these won't damage the wood itself, it can detract from the look of the home so adding a periodic cleaning to your spring cleaning checklist is usually in order.
Before You Get Started
Unlike man-made surfaces like asphalt shingles and vinyl or cement board siding, cedar shakes and shingles do not need to be thoroughly scrubbed and are likely to deteriorate from a rough cleaning. Power washers can be a useful tool, but always start with the lowest possible pressure and test a small area to be sure the pressure isn't damaging the wood. In most cases, washing by hand is fine and a gentle power-washing is best for areas that are difficult to reach by hand, but be sure never to spray up into the shingles or shakes!
Always use caution when working with cleaning solutions and household chemicals. Wear safety goggles and gloves when mixing and applying solutions and be sure to keep products out of the reach of children and pets. Care must be taken when climbing ladders, too. Be sure to read and follow instructions and warnings printed on your ladder, and always inspect the ladder and the area you intend to use it before getting started.
Gather Your Materials
A gentle cleaning solution will help rid your cedar of stains, but choosing the right product depends on what needs to be washed off. For algae and mildew, household bleach mixed with trisodium phosphate (often called "TSP" and easy to find at hardware and home stores) is all you need. Start with five parts warm water with one part bleach and a tablespoon of TSP.
To remove iron stains--or blue-black stains or discolored areas resulting from fasteners weathering or rust washing from windows, flashing, or metal ornaments--oxalic acid is the correct product. Start with a solution of one part oxalic acid and 20 parts water. You may choose to purchase Sherwin Williams Sealer and Stain Remover which is premixed and can be used on this siding. No matter which cleaning solution you're using, experts recommend starting with these diluted mixtures and only adding more cleaning products to the water as needed for stain removal. Once cleaned, it is recommended to use a wood brightener such as Sherwin Williams Revive prior to staining.
The Cleaning Process
Apply your cleaning solution of choice with a garden-type sprayer, a mop, or a soft brush. Wet the surface and try to keep the area wet with the solution for 10 to 15 minutes (for this reason, a cloudy day or even a gentle drizzle are the best conditions). Let the solution do the heavy lifting and avoid aggressive scrubbing. Rinse with clear water, making sure to point the hose in a downward position to prevent spraying up into shingles and siding. If the wood isn't coming as clean as you'd like, try increasing the amount of cleaner slightly until you achieve the results you're after. If you plan on refinishing the wood after cleaning, be sure to allow a few days for the cedar to dry completely.
Now that the shingles or shakes are clean, why not move onto the deck? Five Star Painting offers professional power washing, deck staining and, while you're in the backyard, fence painting too! Before you begin, find answers to commonly asked deck cleaning questions from Window Genie one of our fellow Neighborly brands.