Note: This is cleaning/treatment/restoration only. We do not offer roof repair services.
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What Goes Under Cedar Shingles?

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What goes under cedar shingles and shakes? Whilst it is important that your outer roofing layer is high-quality, it is also important that you have a layer below to help protect from any moisture that may penetrate below. Choosing the right material to go here is important to the longevity of your home.

There are a few different materials that can be used as an underlayment, such as felt underlayment/tar paper or synthetic underlayment.   Each has its own benefits and negatives, we will take a look into those below.

What is Underlayment?

When used for roofing, underlayment is the material that goes beneath the roofing material, in this case cedar shingle or shake roof to help provide protection from moisture and wind penetration. This is important for the longevity of the roof as it protects the main structure.

What Goes Under Cedar Shingles?

There are two main types of material that go underneath Cedar Shingles.  We will take a look at both of these now.

Felt Underlayment

The Benefits of Felt Underlayment / Tar Paper Under Cedar Shingles

Felt underlayment is a great option for anyone looking to protect their home from the elements while also keeping costs low.  It is normally made from natural materials like wood cellulose but it can also be made from synthetic fibers like fiberglass. It is then coated with a protective coating made up of Asphalt which repels water, moisture, and debris that may have got past the cedar shingles or shakes. 

Felt underlayment are usually available in rolls of 15 or 30 pounds.  Using Felt underlayment allows you to add an extra barrier that protects from the weather, reduces blow off, prevents roof damage, and protects the main parts of the roofs structure.

Felt Underlay
Felt Underlayment Cracking

The Negatives of Felt Underlayment

Felt underlayment isn’t perfect for every situation. Felt paper is made of fibers that are stuck together but this also makes it susceptible to tearing apart if exposed to too much moisture or cold weather over an extended period of time. Felt can grow weaker with the passing years, making it a poor choice in areas where wind speeds are high and storms are frequent!  This is also not an ideal roofing material to go underneath a metal roof as it can rapidly  deteriorate under rapid heat.

Synthetic underlayment

The Benefits of Synthetic underlayment Under Cedar Shingles

If you’re looking for a way to protect your home in an efficient way, from harsh weather conditions, and a material that is durable synthetic underlayments is an excellent choice. They are made with synthetic materials, and are designed specifically with different types of roofing in mind so they stand up well against various climates and elements without showing signs of wear or tear! 

They are generally made from one or more of the following materials: polyester, fiberglass, polyethylene, and/or polypropylene.  Synthetics underlayment can actually be used on roofs that will see frequent storms, or a wide range of weather conditions as it can with stand alot.   Synthetics underlayment also provide additional insulation which means heat loss is less likely – this might help save money on heating bills over time!

The Negatives of Synthetic Underlayment

Most people in the roofing industry agree that synthetic underlayments have fairly few drawbacks.  But, it does cost significantly more than felt and is also not as waterproof so if there is a continued leak the water may penetrate after a period of time (depends on the quantity of water).  With this said synthetic underlayments do last longer, with stand heat better, so these become less of a disadvantage over time.

Conclusion Between Felt Underlayment/Tar Paper and Synthetic Underlayment

In conclusion,  it is important to consider What Goes Under Cedar Shingles or shakes as it will vary depending on your needs and local climate, thinking about the weather you have, the conditions and the moisture in the atmosphere and the moisture that hits your cedar shingles in the form of rain and snow.  Each of the different underlayments have their own pros and cons but each one has different benefits depending on where you live, what you need, and what you are looking for from your roof.

Synthetics can last longer, offer better protection from heat and normal wear, but they are more expensive.

Felt underlayment is cheaper and more water-resistant but may deteriorate faster especially when hot.  Felt underlayment can last for decades if the cedar shake roof itself is maintained correctly.

What Else Can Be Done?

If you are considering a roof replacement the first thing to know is do you actually need one?  Having your roof cleaned costs about 5% the price of a new one and can extend the life of your roof for years to come.  Roof replacement is a story often sold to people who have cedar shingle or shake roofs that look in poor condition – it is not a commonly know fact that cedar shingle and shake roofs need to be cleaned.  

It is often the case that a cleaning of the roof will actually save it and extend its life for years to come!  This is because moisture and debris damage the cedar shingles and shakes and removing this allows them to breathe and produce their naturally protective oils again whilst also removing the organic matter that is causing the issues.

Making sure that you have decent protection on the top in the form of a cedar shingle or shake roof, and on the bottom in the form of felt underlayment/ tar paper, or synthetic underlayment, it is also important to ensure that the roof is clean and free of organic matter and debris.  Organic matter and debris on a cedar shingle or shake roof will cause premature deterioration of the roof which would then put the underlayment material of your choice to the test.  Ideally, this will not be tested!

Bruce Sullivan offers professional roof cleaning to remove all problems from the roof such as fungus, algae, moss, mold, and other organic matter.  Keeping the roof clean will allow the cedar shingle or shake roof to work as it was intended and it will also add years to your roofs life.  A cedar shingle or shake roof is meant to last for around 40 – 50 years but many are replaced after 20 years (unnecessarily) due to poor maintenance.  A roof only needs to be cleaned once every 5 – 10 years depending on local conditions and should be kept free of leaves and debris more regularly if possible.

Sullivan Cedar Shake Roof Cleaning never uses pressure washing and will never walk on a cedar shingle or shake roof.  Both of these methods are commonly used but will damage your roof more than it actually helps.

Give Sullivan Cedar Shake  Roof Cleaning a call or message today and get a quote to clean your roof and keep it working as it should.

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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