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Roof Oil Treatment: Why You Should NOT Use Cedar Shake Roof Oil Treatment

Cedar Shake Roof Oil Treatment


In this article we will look at some of the issues of using a cedar shake roof oil treatment on your wonderful roof.

Cedar Shake Roof is an organic roof that is made of cedar wood and provides a natural, rustic and beautiful look to a house that is eco-friendly as well. Unlike other roofing materials, Cedar Shakes require a little more maintenance and care due to their organic nature. Cedar Shake Roofs need maintenance and repairing roughly once every 5 – 10 years depending on your local weather conditions and climate.  Regular maintenance of the roof requires professional assistance in order to make sure the cedar shake cleaning is done correctly and does not cause any damage to the cedar shake roof.  An inexperienced person, whether professional (paid) or an amateur can cause serious damage to cedar shake roofs through the use of improper techniques and cause broken, cracked, damaged or curled shakes that need to be replaced, this may be due to incorrect cleaning techniques or walking on the roof

However, it is a fact that the maintenance of a Cedar Shake Roof is required by the cost of this is only about 5% of that of a new roof. If a cedar shake roof becomes covered in infestations and organic growth then it cannot breathe, dry, expand and contract in its typical natural way, the effects of this are much like the problems caused by cedar shake roof oil treatment. Wooden Shakes expand and contract due to rain and sunshine that make it age naturally and if there is a substance which blocks this then it can cause big problems.

However, sometimes shakes get old and give a faded look and lose their original color over time. Moreover, heavy rain and sunshine can damage the surface of the shakes. As cedar shakes age they become faded and lose their original color so some people believe that oiling the shakes is a way to restore this, it is not needed.  A cedar shake roof needs to be kept free of moisture and to do this it is simply a case of cleaning every 5 – 10 years and removing any growth that may have occurred. Staining or sealing Cedar Shake Roof with oils and other sealants is not recommended by cedar shake experts but it is often recommended as an addon by general roofing “experts”. 

Cedar Shake Roof Oil Treatment

Cedar Shake Roofs in an area with heavy rain and wet climate need to dry out properly. An oil treatment does not allow the shakes to breathe and dry out properly. Cedar Shake Roof oil creates a seal and a layer of oil on the wood that locks everything inside the wood, anything that is inside the wood at the moment of it being sealed will remain. Moreover, seasonal changes require the wood to contract and expand in a natural climate and dry out excess moisture in the wood – Cedar Shakes need air to stay dry which is impossible with an oil treatment. So, a Cedar Shake Roof oil has no benefit for the roof.

Cedar Shake Roof oil

Here are some disadvantages of roof oils that clearly show that Cedar Shake Roof oil treatment should not be used on roofs: 

Locks Moisture

Wooden Shakes in a humid area need to breathe and dry out in natural air but oils can seal and lock the moisture into the Shakes and shorten the lifespan of the roof. Moisture in wooden shakes during the rainy season needs to evaporate in normal weather conditions. But if the roof is sealed with oil treatments the excessive moisture in the roof cannot evaporate and thus decreasing the lifespan of the roof. Therefore, it is not recommended to use Cedar Shake Roof oil as it adds no value to the roof. 

Locks Moisture

Increased Flammability

Wooden Roofs are normally flammable and risk catching fire easily in a dry atmosphere due to excessive heat. Cedar Shakes do not have fire resistance due to their organic nature. So, if Cedar Shake Roofs are treated with added chemicals and especially oil treatments, they can become even more flammable! Cedar Shake Roof oil has no beneficial effect on your roof and should be avoided even if it apparently enhances the natural look of your roof. 

Increase Flammability

Encourage Mildew and Fungi Growth

Cedar Shakes have a common problem of mildew, algae and fungi due to rain and in a humid atmosphere when combined with organic growth and infestations. However, the growth of mildew can be cleaned out properly with a good cleaning by cedar shake roof cleaning professionals. However, excessive moisture into the roof is locked due to a Cedar Shake Roof oil treatment and thus causes the mildew, algae and fungi to grow faster inside the shakes. So, this is another reason that Cedar Shake Roof oil should be avoided by roof owners, do not fall into the marketing trap. 

Encourage Mildew and Fungi Growth

Seal in Infestations & Rot

As you know, Cedar Shake roofs are made of wooden shakes all aligned in a pattern to encourage the flow of water to descend, as the water clears the shakes will dry themselves out (if not covered in any infestations of moss, fungus, or other organic matter. 

Typically cleaning the roof will help to preserve it and remove any infestations, sealing this can cause issues when attempting to clean and remove them. Treating the Cedar Shake Roof with oils should be avoided – even though some roofers will tell you about the benefits, the main benefit to them is that it fills their pockets!

Seal Infestation

Suffocate the Shakes

Cedar Shakes are organic and need to breathe with the passing of air in the form of wind in a natural atmosphere. However, oil treatments can restrict this flow of air and  “suffocate” the shakes and as the oils do not allow the roof to breathe and dry out properly after rain. So, yet again Cedar Shake Roof oil treatment needs to be avoided to to ensure your cedar shake roof can function correctly as it should. 

In Conclusion

Finally, it is right to say that Cedar Shake Roofs are the best organic and natural-looking roofs that give an attractive and rustic appeal to your home. The beauty of the Cedar Shake Roof lies in its natural look that is well maintained by a cedar shake professional roof cleaner.

As discussed in this article Cedar Shake Roof oil treatment can harm the natural look of the roof, they also shorten the lifespan of the roof when it is treated with oils and sealants. This is because oils and sealants prevent Cedar Shakes from breathing, drying, expanding and contracting that are natural with wooden material.

If you are looking for other ways to help your roof you can trim back trees so the foliage doesn’t gather on the roof, keep your gutter clear of leaves and other debris. And finally, the best way is to let your roof get its natural lifespan of 40 – 50 years without any treatment or sealant is to have a regular cleaning around once every 5 – 10 years and enjoy your beautiful roof!

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.


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