Restoration Guide: Roof Shingles and Shakes

Editor's Note: This is article 7 of 13 in the Roofs Chapter of the Old House Web Restoration Guide. This guide was developed and edited for old homes from original material in the U.S. Housing and Urban Development (HUD) Guide.

WOOD SHINGLES AND SHAKES

Section 1--The Basics

Wood roofing has been around since man learned to split and saw wood.

While various woods have been used in the past, nowadays shingles, and their meatier cousin, the shake, mostly are made of various cedars: western red, eastern white and Alaskan yellow cedar. Shakes also are made, to a much lesser degree, from pressure-treated southern yellow pine and redwood.

As might be expected, western red cedar ages to a darker gray than white and yellow cedar or yellow pine. Redwood weathers darker than red cedar.

Section 2--Maintenance and Repair

Shakes and shingles last longer in colder climates than in hot climates. If certified by the Cedar Shake and Shingle Bureau (CSSB), they are warrantied against material defects for 20 years, though they can be expected to last longer in colder climates. Several elements affect the lifetime of shakes and shingles, including:

• The building site
• Local climate
• Shingle grade
• Installation

The CSSB recommends that cedar shakes and shingles be attached to spaced sheathing (1x6 boards with like spacing between), though horizontal furring strips can be attached to solid sheathing. The spacing provides an air gap for the shakes to breathe and reduce moisture buildup.

In jurisdictions where solid sheathing is required, shingles can be attached to the solid sheathing. In this case, it is preferred that they be pressure treated with preservative.

2.1: Repairing Cedar Shingles and Shakes

Cedar roofs can become unsightly with dirt, moss, and lichens. Such roofs can be pressure-washed, but only with extreme care. It is very easy to damage shakes with a high-pressure washer. The CSSB has information and products on shake maintenance to help avoid a premature home renovation.

While the overall condition of your shake or shingle roof may be sound, individual pieces still can go bad. Fortunately, individual shakes are easy and cost-effective to repair. If a shake has split, but otherwise does not show serious decay, it can be repaired with the insertion of a metal shim underneath it. A shake that is showing obvious decay--spongy or crumbly--needs to be removed and replaced. The old shake can be lifted slightly with a pry bar and the nails cut with a hacksaw to remove the shake with minimum disruption to the roof.

Spot replacement of shakes is only effective if your roof generally is in good condition. An old house with a roof spotted by new shakes amongst the worn shakes is a sign that the roof should be replaced; you are just asking for leaks to develop by postponing the necessary home renovation.

Section 3--Materials

3.1: New Cedar Shingles

There are four grades of cedar shingles, as rated by CSSB (manufacturers who are not members of CSSB may have their own rating systems):

• No. 1 Blue Label. The top grade, these shingles are 100 percent clear heartwood and vertical grain. They are the longest lasting and least likely to split or curl. They can be purchased natural or impregnated with fire retardants. They also can be pressure treated with preservative (CCA), with up to a 30-year warranty against rot and fungus. The shingles cannot be treated with both the fire retardant and preservative.
• No. 2 Red Label. This second level of shake can be used under conditions where the roof is somewhat protected, but because they have some flat grain, they do not hold up as well as the top grade. No. 1 shingles are considered to be more cost effective.
• No. 3 Black Label. These are considered to be a utility grade, suitable for secondary buildings and economy applications.
• No. 4 Under Coursing. These are suitable for shims or for using as under coursing under a top layer of No. 1 or No. 2 shingles.

Because cedar shakes and shingles are rigid, they are more resistant to high wind than the flexible asphalt shingles.

Both shakes and shingles are considered to be a renewable resource.

3.2: New Cedar Shakes

Shakes are heavier and thicker than shingles, giving a rugged, rustic look. There are four types of cedar shakes:

• No. 1 Handsplit and Resawn. The most common shake, these are made by splitting a chunk of wood off the cedar log, then sawing it at an angle creating two tapered shakes. The split side gives the rugged appearance, while the sawn side faces down.
• No. 1 Tapersawn. These are sawn on both sides.
• No. 1 Tapersplit. These are split by hand, and both sides have a split surface.
• No. 1 Straight Split. These shakes have no taper and are most often used on walls.

Like shingles, shakes can be treated with preservatives or fire retardants (though not both). They are considered a sustainable resource.

Also like shingles, they are more expensive than many other types of roofing and, unless treated, are very combustible.

3.3: New Southern Yellow Pine Shakes.

Marketed mostly in the East and Midwest, yellow pine shakes are available as No. 1 and No. 2 taper sawn. They are thicker and denser than cedar shakes.

All yellow pine shakes are treated with preservative and are warrantied for 30 years against decay, rot, and termites. They can be applied over solid sheathing because they have been treated, but venting with furring strips still is preferred.

They cost about the same as untreated cedar shakes, and like cedar, they are considered a renewable resource. Because they weigh more than cedar, the roof trusses/rafters may need some reinforcement. Because they are treated with preservative, they cannot be treated with fire retardant.