Cedar Roofing: Modern Use of a Classic Roofing Material
Cedar has been used for roofing for hundreds of years, largely because of its durability, moisture resistance and aesthetic appeal. It doesn’t suit every home and is not advisable in wet climates but, if properly located and the “old-world” look is what you are after, it may be the right solution.
Cedar roofing can be in either of two forms: shakes or shingles. Shakes vary in width from 5” to 12” and when installed impart a more rustic look. Shingles are narrower, typically 6” to 8” and appear more regular. Either type can red or yellow but in either case, will turn the typical grey colour within a year or two unless treated.
Cedar has a lot going for it as a roofing material but be prepared for its higher cost – about 2.5 times that of shingled roof. That’s do to higher costs for the material and greater time required for installation.
- Cedar characteristically turns grey within a couple years so if you don’t want that as your final roof colour, plan to treat it to prevent greying or choose something else.
- Cedar has a long lifespan if properly installed, on average 25 – 50 years.
- Cedar is a natural material.
- Cedar is a good insulator, effectively adding an R10 value.
Grading & Stamping – Indicators of Product Quality
Being a natural material, it is more difficult for the average homeowners to discern differences in quality. In the end, you really have to rely on the company installing it but there are some ways to verify their claims.
Legitimate, North American cedar shakes and shingles are graded by the Cedar Bureau that applies standards which indicate the estimated lifespan. Graded materials will bear a stamp – foreign sourced materials are not part of this grading system.
Measuring the thickness of the shakes is a good indicator of the projected lifespan. Shingles with a thickness at the face of 3/8” to 1/2” are generally good for 25 years, shingles with a thickness of 3/4″ – 1 1/4″ have an expected lifespan of 50 years.
Getting Proper Installation
The installation time for cedar is greater than that for standard shingles and requires additional preparation. Proper installation has a big impact on the lifespan so you should discuss the methods being used before the material is installed and check during application to see that they are followed.
The major culprit affecting cedar roofs is moisture. If it cannot dry out and stays wet, the shingles will rot. To prevent this, the roof needs to “breathe”. For this to happen an airspace is needed between the shake and underlying roof. This requires that roof be strapped with a cedar breathing strip, which the shingles are nailed to or a wire mesh membrane. Essentially, the shakes “float” above roof allowing air to circulate on the underside to permit drying.
A proper installation follows a series of steps, similar to those for fiberglass shingles and other materials.
- Install ice and water shield to protect the valleys and edges along eavestroughs.
- Cover the roof with breathable underlay.
- Apply strapping
- Insert 18’’, 30lb felt paper between every row of cedar as the shakes go down.
Because cedar is susceptible to mold and moss growth, especially if it stays damp, it is advisable to use copper or zinc strips at the ridge vents. The copper or zinc oxide that is created when these materials rust is a natural fungicide that helps prevent these problems. Cedar also accelerates the rusting of nails so they should be either zinc plated or preferably, stainless steel.
The reveal is the shingle area exposed between rows – the more shallow the reveal, the more shingles required and the higher cost but this translates into a longer lasting roof. The reveal can range between 5” and 10” and should not exceed the higher value.
To last, cedar does require periodic maintenance. If you can’t do the work yourself, it is advisable to purchase a maintenance package when it is installed. The first year is frequently included in your contract. Due to the nature of the material, it is common for some shingles to loosen and will need to be replaced or simply reattached. Accept this as normal.
General maintenance focuses on fixing loose shingles, removing moss or fungus and checking for excess moisture, which if installed correctly should not be a problem. Spraying the roof with a zinc or copper based solution is a good way to prevent moss and fungus.
A properly aging cedar roof, without a colour treatment will naturally turn to grey, often within 12 months. If patches start to turn black, it is starting to rot and requires immediate attention.
The Key Considerations When Getting a Quote
Because of the variations on material and installation methods, you need to ask several questions of the roofing contractor to reconcile why there may be differences in price.
- What is the expected lifespan of the material?
- Is the cedar properly graded? Ask to see a sample.
- How much reveal will there be?
- How is it being installed? Ask for a detailed description.
- What is there warranty on workmanship?
If possible get a reference or two to a previous customer and do a drive-by to see how it looks from the street.
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