Note: This is cleaning/treatment/restoration only. We do not offer roof repair services.
Cedar Site Logo

Why Do Cedar Shakes and Shingles Weather?

Why do Cedar Shakes and Shingles Weather 850x433


What Causes Cedar Shakes & Shingles to Weather?

All cedar shakes and shingle roofs will experience weathering. Weathering is simply the breaking down of an element (in this case, a cedar shakes or shingle roof) due to exposure to the elements over time. There are three main factors that contribute to a cedar roof’s weathering:

  1. Solar Radiation
    Solar radiation damages the cedar shakes and shingles rapidly, and is the most easily seen. Sunlight will cause the color of the cedar shakes and shingles to change from its natural golden hue to a silvery gray. This color change is an indication that the lignin (the natural glue that holds the wood cells together) is breaking down. As the lignin breaks down, tiny cracks in the cedar shakes and shingles occur which allow excess moisture to creep in and create further damage.
  2. Moisture
    Moisture causes the cedar to swell, and then shrink as it dries. This is known as the wet-dry cycle. After repeated wet-dry cycles, the cracks in the cedar from the solar radiation grow larger and deeper. This means even more moisture will get deeper into the shakes and shingles, preventing the cedar from drying quickly. As a result, the shakes and shingles begin to warp.
  3. Wood-Destroying Fungi
    While cedar contains natural preservatives, these preservatives are depleted over time due to solar radiation and moisture. With the absence of the natural preservatives, wood-destroying fungi (such as white-rot fungi and brown-rot fungi) creep in and start to colonize and grow. In the right environment, these fungi grow rapidly and eat away at the wood. White-rot fungi cause the shakes and shingles to become soft and spongy, while brown-rot fungi cause the shakes and shingles to crack and crumble. Without cleaning the fungi from the cedar roof at the early stages, the shingles and shakes will need to be replaced, and the homeowner risks premature roof failure.

*This article contains information gathered from Journal of Light Construction 1992

Cedar Shake Roof Cleaning in Des Moines Iowa
Cedar Shake Roof before & after cleaning

Meet Bruce

50 Years of Experience &
Over 2,000 Shake Roofs Cleaned

Bruce Sullivan has over 50 years of experience in maintaining, cleaning, and restoring cedar shake roofs. Making him one of the top authorities on cedar shake roofs in the US.

Watch the Cedar Shakes Cleaning Process in Action in this video

Play Video about Roof Cleaning How to Remove Moss, Lichen, Fungi from a Cedar Roof Sullivan Roof


What can I say? Bruce and Keith provided an exceptional service, and they are really nice guys too. Found out at the last minute they were in Minneapolis, and they fit me in for a cedar shake roof cleaning the next evening after their regular job was done. Even cleaned up my gutters, small fence, and small deck at no charge. The place looks outstanding! Highly recommended.

Mike Richards

I highly recommend this business. Due to the work performed we are going to get another 10-14 years out of our cedar shake roof. We were told by some roofing companies that the roof should be replaced in 2 years. I lucked out and found Sullivan Roof Cleaning while researching companies that perform this service, and was pleased to learn that the company does work outside of Iowa. If you need your cedar shakes cleaned, go with Sullivan Roof Cleaning.

Eric Oelrich, 
St Cloud, MN

Bruce did a great job cleaning the whole exterior of my house. The roof has new life! It looks practically brand new. All the mold and moss on the roof, on the gutters, under the eaves, completely gone. He exceeded all our expectations. When he tells you what he can do for your house, you can believe and trust him. Great guy, great service.

Stuart Malone
Kansas City, MO


Cedar shakes are organic. Though a resilient material. Being organic they need to be maintained. Over time, like any organic material that are subjected to weather elements, they reach a stage of deterioration. Like UV exposure, moisture and seasonal changes. Which results in moss, mold, mildew, lichen and brown rot fungi. These infestations need to be removed to further preserve the integrity of the cedar shake.
The proper way to clean a cedar shake roof is from a ladder. By spraying a special formulated solution onto the shakes and then rinsed with a garden hose pressure. Best done by a professional cedar shake roof cleaner. Not DIY recommended.
No. Pressure washer will require walking on the shakes, which will harm them, and even at its lowest setting will also damage the shakes.
On average, cedar shakes should be cleaned every 10 ten years. Subjective to the grade of the shakes and the amount of surrounding tree cover.
Avoiding walking on a cedar shake roof, other than for repairs.
Never seal a cedar shake roof. Cedar shakes need to breathe. They expand and contract in rain conditions. Seal will shorten the lifespan, to the point of premature replacement.
Staining has no real preserve value and can also harm the integrity of shakes, as stated, they need to be able to breathe. Also, if the shakes are not properly cleaned staining can seal the deteriorating infestation within the shakes.
Depending on the grade of the shakes and installation, and if maintained properly, 40 to 60 years.


Free No Obligation Estimation

Recent Posts

Free No Obligation Estimate