Cedar shake enjoys continued market demand even though more durable and low maintenance roofing materials, such as metal and vinyl, are available. Cedar shake has a unique aesthetic appeal, and its brown shade can enhance the appearance of rustic-style buildings. On the other hand, even the highest quality cedar shake roofing material requires more TLC than other roofing materials.
Shell Busey, in a recent article that was featured on Canada.com, advises caution on the kind of TLC you give your biodegradable cedar shake roof. Roof cleaning products and methods remain largely unregulated, and the use of improper cleaning products and methods could damage your cedar shake roofing. In fact, even the act of pressure washing could inflict irreversible damage.
However, this doesn't rule out the option of power washing, as it's a necessity for every roof. Just have it done by a professional about twice a year. An excerpt from Busey's article states that: “Cedar roofing should be cleaned regularly, spring and fall, with medium pressure or enough to remove debris that accumulated during the previous months, and inspected in preparation for the next season.”
Cedar wood is renowned for its endurance and can survive for centuries. The natural oils found in cedar trees enables it to live for as long as a thousand years. For roof cleaning, however, the Cedar Shake and Shingle Bureau (CSSB) recommends topical treatments that come with a material safety data sheet (MSDS) that lists product ingredients and safety precautions, as well as certifications.
Busey goes on to warn readers about the dangers of using certain topical roof treatment products:
Do not use a topical treatment product that claims to be fire-retardant or have a 10-year effectiveness. Also avoid sealants, waterproofers or plasticizers, or products that contain unfortified linseed oil, diesel fuel or crankcase oil. Topical solutions such as latex, butyl or silicon, "seal" or coat the surface of the cedar preventing it from "breathing". Anything used as a topical treatment should be [labeled] as a cedar roof treatment product or have a manufacturer's letter stating that it's appropriate for treating cedar roofs.
For quality wood roofing supplies, home builders, contractors, homeowners, and resellers should get their cedar shingles and shakes from renowned suppliers like WoodRoof.com. High quality cedar shingles and shakes are biodegradable, wind resistant, light weight, impact resistant, and of course, durable.
(Info from Keeping on top of your cedar roofing problems; Canada.com, via The Province)