A house with wooden roofing shingles has been a common sight in America from colonial times. This prevalence was thanks not only to an abundance of forests, but also early settlers' ability to make and install wooden shingles on their home. Originally made from the heartwood of a variety of locally growing trees, homebuilders would split these first shingles manually using a mallet and froe. The homebuilder or carpenter would smooth them with a draw knife to ensure that they would lie flat.
The introduction of steam-powered saws in the early 19th century revolutionized the shingle industry. Suddenly, mass production of uniformly cut and finished shingles was possible. Throughout the century, inventors continued to produce machines that refined the shingle-making process. In 1857, the government issued 19 patents for machines designed to make shingles.
By the 20th century, wood dealers and homebuilders were paying more attention to the kind of shingles used for roofs. In an issue of The American Lumberman from September 1923, the British Columbia Shingle Manufacturers Association announced they were going to begin an extensive campaign to advertise the advantages of edge-grain shingles over flat-grain shingles, featuring the slogan, “A roof is only as strong as its weakest shingle.”
These days, wooden shakes or shingles aren't as common a sight as they were in the past, but many people still choose them for their beauty and durability, especially if they live in older or more historic homes.
Even more so today, the kind of grain you select for your shingles makes a difference in the quality of your roof.
About Trees
Let’s pause for a minute to think about the way a tree grows.
At the very center of the tree is the pith. It’s softer and has a different color than the heartwood that surrounds it. Heartwood — the best kind of wood to use for a wooden shake or shingle — is primarily dead cells that now only serve to support the tree.
Outside the heartwood is the sapwood, which is what carries minerals, water and sugars to roots and leaves. Its color is much lighter than that of the heartwood.
Once you get outside the sapwood, you come to the cambium. Close to the surface, this is a layer of living cells that manufacture the wood. A layer of bark protects them. The cambium layer grows quickly each spring, and then as the warmer weather comes, it slows down and creates darker summerwood. As winter arrives, the cambium goes dormant. This process is what creates growth rings in a tree, which, as you'll learn later, are essential to the quality of a shake or shingle.
Cambium creates two types of wood cells:
Longitudinal cells are long, narrow cells that orient themselves at the axis of the limb, root or trunk. These are what give wood its grain.
Ray cells are so called because they line up in rays that extend outward from the pith.
As the tree grows, the living part of the cell dies and leaves behind just the cell walls, composed of cellulose fibers. These give wood strength. Lignin, a gooey substance, binds the fibers together. Over several seasons, this older sapwood turns into precious heartwood. As sap dries up, mineral compounds gather on the cell walls. These chemicals give the wood its color, with the exact shade depending upon the species of tree. They are also what determines a tree’s stability, hardness and strength.
The Different Grains and What They Mean for Wooden Shakes or Shingles
You’ll often hear roofers, carpenters or contractors who work with wood talk about the grain of the wood. They’ll talk about edge-grain, flat-grain or slash-grain, and what it is like to work with each kind of grain. The reason why this is important to you is that the type of grain you choose for your roofing material will affect your budget, the durability of your roof and its appearance.
The part of a log from which a manufacturer cuts a wooden shake or shingle determines the appearance of the grain. The grain of the cut is vital. It influences the shake's or shingle's long-term stability and how likely it is to split, erode or suffer distortions like twisting or checking. Checking is another way of saying there’s a crack that does not go through the entire shake or shingle.
Carpenters and woodworkers use the terms edge-grain and flat-grain about the orientation of the tree’s growth rings to the sawn surface of a shingle’s or shake’s split face.
1. Edge-Grain Shingles and Shakes
Edge-grain is also known as quarter-sawn, vertical grain, radial grain or rift sawn. It is a straight, tight grain.
They are the most stable of the three main varieties of face grains.
You need to cut perpendicular to the growth rings to get an edge-grain shake shingle. The maximum an edge-grain is allowed to slant is 45 degrees from vertical.
The exposed face of an edge-grain shake or shingle will display the beautifully grained growth rings of the two most popular woods used to make shakes or shingles: western red cedar or Alaskan yellow cedar.
These shingles have the highest resistance to cracking, splitting, eroding or distorting, and provide the most durability over time.
Shingles or shakes will move when their moisture content changes. Edge-grain shingles resist this movement better than other grains.
If you look at the butt end of an edge-grain shingle, the growth rings will be standing on end, vertically, the same way the teeth of a comb do.
You'll pay more for a wooden shake or shingle that’s cut with a 100 percent edge grain, but the shake or shingle will also last a great deal longer — perhaps even as long as 50 years, with proper maintenance.
The very best, top-grade wooden shakes or shingles must be 100 percent edge grain. The next grade down can have as much as 20 percent flat-grain shingles.
2. Flat-Grain Shingles and Shakes
Flat-grain has other names as well: slab sawn, flat sawn, plain sawn or tangential.
There is visible heartwood in a flat-grain shake or shingle.
Manufacturers cut the shakes or shingles parallel to growth rings. When viewed from the butt end, the grain has a horizontal orientation. A shingle’s face displays very wide grain that has an obvious centerline. It presents as an open, swirling grain.
A flat-grain shingle exposes a lot of sapwood, which makes it particularly vulnerable to weather and moisture.
It’s much less stable than edge-grain and very likely to split, erode, check, distort, cup, curl or move.
You can still use flat-grain shakes or shingles when you carefully consider the kind of project and how you intend to apply the shakes or shingles.
Flat-grain shakes or shingles are often a starter course or for re-roofing.
A final word about slash-grain. The “wayward stepchild” of the wooden shakes and shingles family has a wavy grain. They're also cut perpendicular to growth rings, but at a greater than 45-degree angle. This cut exposes much more sapwood than an edge-grain cut. It also makes slash-grain shingles the least stable of the three types, which is why they are unsuitable for a roofing project. They are much more suitable for projects like barns or sheds.
Wood Grades
Wood grades go hand in hand with grain designations. There are four main wood grades:
Grade 1: These premium-grade shingles come from the tree's heartwood and are 100 percent edge-grain, with no defects. Grade 1 shakes and shingles cost more, but provide the greatest durability and the longest life.
Grade 2: These good-quality shakes or shingles have a flat-grain cut with an allowance for some sapwood. Knots and defects are limited above the clear portion that shows when a shingle is installed. As we noted above, this grade is useful for re-roofing or as a starter course.
Grade 3: These budget-quality shakes or shingles have a flat-grain cut and include sapwood. Again, knots and defects are limited, but allowed above the clear portion. Grade 3 shingles are often part of an under-course as part of a two-course application, for garden sheds, or walls of outer buildings.
Grade 4: These utility-grade shingles are not a roofing material, nor are they suitable as a roof's starter course. Their only use is as the under-coursing of double-course sidewalls.
What to Look for When Evaluating Shingle Grain
When evaluating shingle grain, there are some things you need to be on the watch for.
Coverage: The amount of roof an on-grade product in a bundle or carton will encompass is called coverage. Some manufacturers intentionally mislead you by not putting the correct amount of on-grade coverage on a package. Another trick is that they use smaller-than-standard packaging to make the carton look fuller than it is.
Unpermitted knots within a bundle: As we noted above, flat-grain cuts do allow limited knots to be visible on the face of the shingle. Some manufacturers, however, will try to include shakes or shingles that have several unpermitted visible knots.
Thin product, off-grade: If your wooden shakes or shingles are supposed to be a certain size, say half an inch, but are below that size, they are off-grade.
Excessive flat-grain: Remember, grade 1 wooden shakes and shingles are not supposed to have any more than 20 percent flat-grain. Premium grade has none.
Short shim off-grade: Shims can occasionally replace a shake or a shingle. Shims that are too short are off-grade.
Narrow off-grade: These wooden shakes or shingles are narrower than required.
Bark off-grade: These wooden shakes or shingles have a layer of bark along an edge.
Knot off-grade: The very best wooden shakes and shingles are heartwood with no visible knots. If you ordered 100 percent premium-grade wooden shakes and shingles, and some of them have visible knots, they are off-grade.
Make sure the label on the shingles is a genuine Certa-label and not a knockoff. Some manufacturers will try to trick you into thinking their product meets all the quality and grade specifications of the Cedar Shakes and Shingles Bureau (CSSB). CCSB Certa-Labels will have the following registered trademarks: Certigrade®, Certi-Sawn®, Certi-Split®, Certigroove®, Certi-Cut®, Certi-Ridge®, Blue Label® or Envirosmart®. Be wary of attempts to duplicate these labels.
Buying Shingles Based on Price vs. Quality
When you consider using wooden shakes or shingles for a roof, it’s important to remember the advantages of buying higher grade shingles.
Buying cheaper and lower quality shingles can present a few issues:
You will often end up with off-grade material at the job site that will violate local building codes.
You need to buy additional product to cover any shortfall.
There will be an increased number of culls – wooden shakes or shingles that are of such a poor quality that you can't use them.
The roof install may cost more because of the extra labor needed to correct the problems mentioned above.
When buying high grade shingles:
You’ll be working with the product that’s longer-lasting and a better value.
When you choose quality wooden shakes and shingles inspected by an accredited third-party agency, those products will have a longer life expectancy.
Homeowners can obtain viable limited warranties, which will help them feel better about working with quality wooden shakes and shingles.
Contact Custom Shingles to Learn More
If you’re interested in finding out more about the different grains of wood you can use to build a wooden shake or shingle roof and the grades of wood available for your use, contact us at Custom Shingles today. If you want a custom wood shingle roof, we are the premier provider of the shakes and shingles you’ll need. We see this as more than a business — for us, it’s an art form. Custom wood shakes and shingles are beautiful and give an Old World charm to a home. Often, a custom wood shake or shingle roof enhances the appearance of the rest of the home. Best of all, a custom wood shake or shingle roof provides stability and durability for many, many years to come.
You can contact us for information on our products, installing wooden shakes and shingles and even the history of their use. Feel free to call us from anywhere at the world toll-free at 877-323-3553 or locally in the Florida area at 386-487-1055. Or, visit our contact us page, where you can leave us your contact information and tell us a little bit about your project or any questions you might have. A member of our team will get back to you as soon as possible.