How to Restore Your Cedar Roof

Some cedar treatments can do more harm than good. Here's how to keep your cedar roof in fine form for years to come

Credit: iStock / PhilAugustavo

Replace damaged shingles regularly to keep your cedar roof looking like new

Cedar roofing is aesthetically pleasing, but requires regular care to keep it looking fresh and moss-free

In recent years, an entire industry has developed around restoring cedar roofing. But a simple pressure washing isn’t going to fix everything. In fact, it may cause more damage, so it’s important to know how to make educated choices when dealing with cedar roofs.

Organic debris from overhanging trees, wind-blown leaves, dust and dirt combine with the spring rains to promote the growth of moss and algae on your roof. This has spawned an army of entrepreneurs offering to extend the life of cedar roofs with high pressure washing and other treatments while promising unrealistic warranties.

Desperate homeowners see these treatments as a way to avoid re-roofing for another 10 years, when in fact, the damage in many cases has already been done from years of neglect. And the industry is largely unregulated, in the case of both the products and the work force.

Cleaning is essential for roofing of all types, and especially for cedar maintenance. But high-pressure washing (with gas-powered pressure washers) can actually do more damage than good by removing the pulp of the cedar itself.

How to Care for Your Cedar Roof

  • Clean your roof regularly: Cedar roofing should be cleaned each spring and fall (with medium pressure or enough to remove 6 months of debris), and inspected in preparation for the next season.
  • Replace shingles: Damaged and prematurely deteriorated shakes/shingles should be replaced. Ridge caps often separate due to failure of the fastener (which joins the two sides together), causing them to open up. Ridge and hip caps oppose the flow of water along the grain so they tend to break down a little sooner than field shakes/shingles. They should be repaired or replaced as required. Even cracked or warped shakes/shingles can be replaced without losing any watershedding performance.
  • Beware of commercial treatments: Do not use a topical treatment product that makes outrageous claims (such as a 10-year effectiveness); makes fire-retardant claims; is a sealant, waterproofer or plasticizer; or contains unfortified linseed oil, diesel fuel or crank case 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 labelled as a cedar roof treatment product or have a letter from the manufacturer stating that treating cedar roofs is an appropriate use for that product. Cedar has natural oils and natural anti-fungal agents, which is why cedar trees can live for over 1,000 years. Besides pressure treating by the manufacturer before installation, it is difficult to improve on cedar’s natural long-lasting properties.

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