Cedar Roofs Sound Home Resource Center

Cedar Roofs Sound Home Resource Center


The Native Americans used it, so did the pioneers. Today, many builders who want to show their prospective customers that they are building a better quality home will often choose cedar shakes. (Wood shingles are rarely used for roofing in residential construction today). Cedar, as a roofing material, has a long tradition of quality. It also has the look of better quality homes. However, it may be the wrong roof for your house.

In the "good old days" (oh, say pre-1950) there were two basic choices for roofing. If you had the money and wanted a "good roof," you chose cedar; most likely a cedar shingle.

If you didn’t have so much money, then you chose that "new stuff" (composition roofing). The roofer would have told you that the cedar would last 30+ years and that "you might get 15 out of the composition". Today, the opposite is most often true!

Things change and decisions become more complicated, and cedar as a roofing material is no longer the automatic choice for a quality roofing material. In my opinion, it’s the wrong choice!

Most tree trunks contain two types of wood: The "heartwood" which is in the center of the trunk and the "sap wood" which is the living outer set of rings. If we look at a cross section of a cedar log, we will find a 6" wide ring of sap wood at the outer edge (a light colored wood) and the rest of the cross section will contain the darker heartwood. The older the tree, the larger percentage of heartwood.

Heartwood cedar makes for the best shakes and shingles. It is the best for two reasons:

(1) The older heartwood has accumulated some natural toxins which reduce wood rot and insect damage.

(2) Heartwood tends to be straight grained, which means that it can be manufactured into shakes and shingles that will remain flat and true.

Shakes and shingles were usually installed on roofs with a steep pitch (6" in 12" or more); the style of the time. Such steep roofs shed water more easily; an advantage when you are working with a natural product which has some unevenness. In addition, most shakes and shingles were nailed onto strips of wood (skip sheathing) and neither felt nor tar paper was used. Such application methods maximized the drying process of the shingles and slowed down damage from wood rot.

These were wonderful roofs. You doubt my word? Take a trip to Lake Quinault (off highway #101 on the Olympic Peninsula). Stay at the Lake Quinault Lodge (you’ll need reservations) after a nice breakfast. (OOPS! I am getting off track). Anyway, in the valley east of the lake you can see some old structures with 70+ year old shakes which are in very good shape.

The first thing that happened was that we cut down and used up a good proportion of the old growth cedar — the stuff which was mostly heart wood. (By the way — if you have some time after breakfast at Lake Quinault Lodge, there is a very nice self guided nature walk across the street. There are a few of the remaining fine old growth cedars, firs, hemlock the Sitka Spruce. — O.K. O.K. I will get back to work).

The next thing that happened was that we started to build houses with lower pitched roofs, ramblers with 4" in 12" pitches, etc. And we continued to use cedar roofing even though more and more of the material contained sap wood. In addition, due to the smaller size (and higher cost) of the logs, we started to use more flat grained and mixed grained shakes — not the straight grained stuff.

In order to cope with these new conditions, it became necessary (and required) to interlace the shakes with felt (tar paper). The good news was that this step reduced leaks. The bad news was that the tar paper increased the drying time and further helped promote rot in the shakes.

So, as the other roofing materials became ever better in quality, more and more of the cedar was of inferior quality and some of the cedar roofs failed (and are failing) in as little as 6 years.

I will be the first to admit that a good quality cedar roof looks great! Some styles of homes just call for a wood shake or shingle — no doubt about it. In addition, some homeowners associations require re-roofing with cedar shakes or shingles. So, here are the options (in rank order):

(1) Look at some of the many imitation products. You will find that almost every other roofing material comes in a shake or shingle "look alike". (no I don’t like to use imitation material either, but when it works better than the "Real McCoy". ).

I have also found that most homeowner organizations are willing to change the rules and allow for a selected number of "look alike" products to be used; for example, architectural grade composition roofing, concrete and concrete composite tile.

(2) Look at some of the other ‘distinctive’ looking roofs and roofing materials, and the way top quality architects use them. I am thinking about metal roofs, torch down ‘flat roofs’, and various other roofing materials combined with special design elements.

(3) Use factory treated shakes.

(4) Specify "Number One — Blue label" product and have the roofer select out the 25% or so of the shakes which don’t conform to #1 grade. Yes, it’s true up to 25% of the shakes and shingles in a bundle may be "off grade."

Within two years of the installation, have the roof treated with a wood preservative. Every 5 years have any curled or damaged pieces replaced. Have the roof cleaned with a garden blower (avoid pressure washing ) and have the roof repaired and re-treated every 5 years.

Ask your local firefighters about shake roofs and you will get an ear full. They will tell you that wet shake roofs are very slippery. In the summer, a dry shake roof doesn’t just burn, it can explode. And a burning shake roof can through off embers and help spread the fire.

In some parts of the country wood roofs may only be used if they are treated with a fire retardant (not to be confused with shakes treated against rot). As we build more houses in forested areas, roofs with good fire resistance make more and more sense. I picked a metal roof for my cabin in the forest. Concrete and concrete composite products are another good choice.

Good shakes and shingles come from trees which are 100-800 years old (and that’s not a "renewable resource" in my book). If we are lucky, we will use the shakes for 25 years. Once they come off the roof they are of very little value — poor quality kindling.

If we used the same cedar for siding, we could maintain the siding for hundreds of years. We might even change our forestry practices, save more of the remaining old growth, re-plant cedar and other species. Today, very little cedar is being replanted.

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