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Cedar Roof Cleaning & Maintenance

Cleaned, Preserved

Cleaning and preserving cedar roofs is essential for lasting value. Removing the stains, removing the moss from shakes and shingles helps preserve cedar. Darkness and streaks, green stains on the shakes or shingles are caused by harmful microbe growths. They will rot your beautiful roof. Successful results come from gentle cleaning with lasting preservation properties. Wood is restored to its natural beauty. The shakes stay clean for years! Rot is prevented! Money is saved. Wood roofs need a lot of care and maintenance because they rot naturally. Don’t waste your money by hesitating, or by using power washing services, which drain natural resins out of the wood. Let the resins do their job, fighting rot. Gentle ROTban – Cleaning Treatment That Lasts – denies the rot producing organisms the ability to feed. That’s all! They cannot rot your roof if they cannot feed there. You get a beautiful, natural driftwood colour for years, without applying colorant.

Other Issues to Note

While we don’t offer to do all of the following, we will recommend trades people for this kind of work.

Debris must be removed from your roof regularly. If shakes, shingles or ridge caps are failing, they should be replaced individually. This maintenance work requires skill. Be careful to use competent workers. The principles of good roofing must be followed. These roofs are expensive to install, and re-roofing in any material is costly. Saving and preserving your cedar roof increases your net worth through lower cost roofing over the time you own your home.

Cedar shake roofing has been, until recently, a very popular roofing material in the Lower Mainland. It’s beautiful. Concern about the typical short life of a cedar roof has led to fewer new homes using cedar, and most cedar re-roofs involving conversion to modern asphalt materials with plywood first being installed over the cleaned off lath. Why, people ask, don’t cedar roofs last 30 years or more, like they have in the past? Here are some answers.
Before Cedar Roof Cleaning After Cedar Roof Cleaning

Before (left) and after (right) cedar roof cleaning


Firstly, the Lower Mainland and Fraser Valley have a Temperate Rainforest Climate. The environment here is warm, wet and shady a lot of the time. Mold, mildew and moss love this environment. The only other thing they really need, to thrive, is food. That’s your wood roof! They also need a rather acidic environment, which we also have. Acid rain has contributed to this aspect. Secondly, the resin in the cedar is its preservative. A weak cell wall in the cedar’s constitution is very well protected by high amounts of potent resin. The older the tree, the higher the resin content. Old growth cedar trees, 250 years and older, were originally used to produce lumber and shakes in BC. Rare today, these trees produced robust and resilient shakes that resisted rot very well. Today, our wood shakes come from younger trees, which have less resin. Thirdly, the most popular style of cedar shake in the Lower Mainland of BC is the Tapersawn shake. Each Tapersawn shake is sawn front and back, across the butt and up each side. The top is as thin as a feather. The problem with sawing the wood is that it exposes cut cells to the elements. Cells that are sliced through do not have the protection of the cell walls. Cell walls are much stronger than the insides. So each Tapersawn Shake has sawn, soft cell contents exposed to the weather. Thus they rot more easily. When these three issues are combined, the result is that at present, the average cedar roof in the Lower Mainland of BC is replaced before it’s 20 years old. Some roofs are made with pressure treated shakes, and that provides extended life. These shakes dry out, however, and tend to crack a great deal. A study done on re-roof jobs of cedar roofs in 2011 showed that the average cedar roof was being replaced at the age of 19.

For serious consideration

While we no longer practice the trade of cedar roof rehabilitation and restoration, ROTban’s previous roof maintenance services have saved many cedar roofs over the last 18 years.

ROTban’s complete cedar roof restoration system has saved many cedar roofs over the last 16 years. We still have roofs under our care and Warranty that are in the neighbourhood of 25 – 35 years old, while most cedar roofs only last 19 years on average in our local climate. On average, this kind of service, if done correctly adds three or more years of roof life. That saves people good money! Cedar rots, cracks and warps. Maintenance is needed, to get good value. But Proactive maintenance, using ROTban – Cleaning Treatment That Lasts – starting at 5 years of age and following a regular program of treating every five years or so, can greatly forestall the rot.

The destructive growths on cedar roofs are not necessarily visible, like moss and lichen are. A thin coating of mold, mildew and algae is seen as a gradual darkening of the wood. If the darkening is in blotches and streaks in a roof 10 years old or more, it is likely pressure treated. There will be a lot of rotting wood on a cedar roof 14 years or older, even if there is no visible moss.

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