Dos and don'ts of maintenance when it comes to cedar shakes

Q: I had four different contractors look at my cedar shake roof for a cleaning and treating. Each had a different idea of what should be done, and each claimed their particular chemical treatment is the best, knocking the others as ineffective or potentially damaging.

Some say stain the shakes, others want to pour linseed oil on them, one said leave the roof bare after cleaning, and another wanted to put on a very expensive proprietary treating material. Can you help provide me with some guidance?

A: The Cedar Shake and Shingle Bureau (CSSB) is a widely respected industry association, not trying to sell any one particular roof-treatment product or method. As there are many inexperienced people performing roof cleanings and treatments, CSSB many years ago developed a certification program, their Roof Maintenance Technician (RMT). Unfortunately not a single RMT is located in the state of Washington.

Lacking a certification that can be uniformly trusted, Lynn Christensen, director of operations at CSSB, suggests asking a contractor for addresses of roof-cleaning customers from several years ago. Drive out and take a look at the roof years after it has been treated to see how it holds up.

The debate over the wisdom of regularly cleaning a cedar roof finds yours truly falling squarely on the side of regular maintenance and treatment. CSSB is still sitting on the fence, but does state that if a roof is pressure washed, a topical treatment should be applied.

The contractor will need to assess each roof on a case-by-case basis to determine if pressure washing, air cleaning or chemical/broom cleaning is most appropriate for the age and condition. Cedar roof cleaning without proper safety equipment and experience can be trouble, so it is not a recommended homeowner chore. Be sure the person performing the work is experienced.

Here's what to look for in choosing a topical covering:

• The product is labeled as a cedar-roof treatment product.

• It is a water repellant, UV inhibitor, and a registered EPA wood preservative.

• It has a manufacturer's performance guarantee.

Here's what to avoid:

• All outrageous-sounding claims.

• Fire-retardant claims.

• Sealants, waterproofers or plasticizers (wood breathes).

• Unfiltered linseed oil, diesel fuel or crank-case oil.

CSSB has produced an electronic and printed version of its maintenance brochure, available at www.cedarbureau.org, PO Box 1178 Sumas, WA 98295-1178, or 604-820-7700 (that Canadian phone number is not a misprint.

They are physically located just over the border, despite the Sumas mailing address).

Darrell Hay answers readers' questions. Call 206-464-8514 to record your question