Key design details & references for wood shingle roofs
Wood roof inspection checklist
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Here we illustrate and discuss wood shingle roofing in historic and contemporary use, we describe proper wood shingle or wood shake roof installation details, and we provide a wood roof inspection checklist. Our page top photo shows a lichens and moss covered roof located in Key West, Florida, viewed from the Key West lighthouse. If you are not sure of the difference between a wood shingle and a wood shake, wood shingles are saw-cut and have smooth flat surfaces, while wood shakes are split (by hand or by machine) to produce a thicker and more irregular product. As Carson Dunlop point out in their Home Reference Book, most wood shingles are white cyprus (most durable), cedar (western red cedar or white cedar) but in some locales redwood shingles are also used, and white pine shingles, yellow pine,and spruce have been used. Also see Wood Shakes & Application Details.
Carson Dunlop's sketch (left) illustrates a source of variation in the quality of wood shingles that depends on how the shingles are cut from the log. The Carson Dunlop sketch at right illustrates the different qualities of wood shingles and wood shakes used on roofs.
Wood Roofing Shingle Specifications & How are Wood Shingles Nailed onto a Roof?
Wood roof shingles are typically 16", 18" or 24" in length and up to 13" in width (but limited to 8" in width in some building codes).
The shingles are 4/10" to 1/2" in thickness, and wood shingles are installed with a 5" exposure (16" shingle length), 5 1/2" exposure (18" shingle length), or 7 1/2" exposure (24" wood shingle length).
The typical life of a wood shingle roof is 30-40 years, but life expectancy varies considerably depending on how the shingles were installed as well as on the pitch of the roof (its slope), and its sun and weather exposure. (Too much sun dries out the shingles leading to splitting, and too much shade may keep the shingles too damp, leading to rot.)
Shingle quality and shingle treatments (for example with preservatives or with protection against photoxidation) are important life factors as well. Wood shingles are installed on roofs with a slope of 6" in 12" for best performance but may be on a slope as low as 4/12.
Wood shingle head lap in a good installation exposes no more than 1/3 of the shingle to the weather. The head laps are 6", 7", or 9" respectively for 16", 18" or 24" long shingles respectively. More details are at Wood Roof Inspection Guide.
Wood Shingle Fastener Specifications
Wood shingle nails need to be long enough to penetrate 1/2" (3/4" for the UBC) into the roof wood decking or nailing boards. The diamond-shaped nail tip itself has no holding power, just the roofing nail shank. So if you see shingle nails protruding through a plywood roof deck, that is not an error.
Nail specifications for wood shingles may vary by wood species; using western red cedar as an example, nails are to be corrosion resistant hot dipped galvanized, stainless steel, aluminum, or copper. In dry climates, good quality electrogalvanized staples, conforming to ASTM A641, are satisfactory according to the Cedar Shake and Shingel Bureau, but from our field experience we prefer nails.
Do not use blued steel or copper fasteners with cedar shakes or cedar shingles.
Wood shingle nailing pattern: in most applications only two nails are used per shingle, in order to permit movement without splitting as the shingle expands and contracts during changes in its moisture level. Keep nails about 3/4" to 1" (1" is for the U.B. Code), away from the side edges of the shingles and 1 1/2" (2" for UBC) above the butt line of the following course.
According to the Cedar Shake and Shingel Bureau, fasteners should be driven flush with the shake or shingle top surface, but no so deeply that the head crushes the wood.
For added details about proper wood shingle or wood shake roof installation, perhaps the most authoritative source of wood shingle and wood shake information is from the Western Red Cedar Shingle & Shake Bureau (now the Cedar and Shake Shingle Bureau, since not only western red cedar is used for roof shingles).
In order to restore some of
Pennsylvania’s historic buildings,
the authors are recovering a lost
trade practice.
Over the past decade of working on
side-lap-shingle roofs, the authors have
observed many earlier attempts by
others to make the process of replicating
these roofs faster and less expensive.
These attempts have included substituting
materials, sawing and planing shingles
rather than riving them to speed the
manufacturing process, and adding
other materials between courses to
reinforce the roofing system. All of
these attempts have saved money and
time in the short term but have failed to
perform long enough to realize the
savings.
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Additional technical contributors & reference sources for this article are listed below.
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"Choosing Roofing," Jefferson Kolle, January 1995, No. 92, Fine Homebuilding, Taunton Press, 63 S. Main St., PO Box 5506, Newton CT 06470 - 800-888-8286 - see http://www.taunton.com/FineHomebuilding/ for the magazine's website and for subscription information.
Problems in Roofing Design, B. Harrison McCampbell, Butterworth Heineman, 1991 ISBN 0-7506-9162-X (available used)
The Cedar Shake and Shingle Bureau in the U.S.: Cedar Shake and Shingle Bureau, P.O. Box 1178
Sumas, WA 98295-1178, or in Canada: Cedar Shake and Shingle Bureau, #2 - 7101 Horne Street
Mission, BC V2V 7A2, 604-820-7700 E-mail: info@cedarbureau.com. The association can also be contacted by their website, cedarbureau.org where the association offers wood shingle installation instructions in the form of a manual - cedarbureau.org/installation/wall_manual/introduction.htm
"Treatment of Cedar Shakes and Shingles," David Flickinger, RRO, Professional Roofing, October 1999, Rosemont IL.
Sharon C. Park, Preservation Brief 19: The
Repair and Replacement of Historic Wooden
Shingle Roofs (Washington, D.C.: U. S. Dept.
of the Interior, 1989), 6.
Johan Heinrich Jonas Gudehus, “Journey to
America” (1829), trans. Larry M. Neff, re-
printed in the Publications of The Pennsylvania
German Society 14 (1980), 307. “The houses
of the Americans as well as their farm buildings
have wooden shingle roofs that are so thick
and solid that a ray of light can come through
nowhere. These roofs are painted red, brown
or dark blue with oil color and on most of
them is to be found a lightning rod…”
Robert C. Bucher, “The Long Shingle,”
Pennsylvania Folklife 18, no. 4 (summer 1969):
51–56. This article was the first study of side-
lap shingles and the primary source of basic
information for "Fabricating and Installing ... " above.
Books & Articles on Building & Environmental Inspection, Testing, Diagnosis, & Repair
Our recommended books about building & mechanical systems design, inspection, problem diagnosis, and repair, and about indoor environment and IAQ testing, diagnosis, and cleanup are at the InspectAPedia Bookstore. Also see our Book Reviews - InspectAPedia.
The Home Reference Book - the Encyclopedia of Homes, Carson Dunlop & Associates, Toronto, Ontario, 2010, $69.00 U.S., is available from Carson Dunlop, and from the InspectAPedia bookstore. The 2010 edition of the Home Reference Book is a bound volume of more than 450 illustrated pages that assist home inspectors and home owners in the inspection and detection of problems on buildings. The text is intended as a reference guide to help building owners operate and maintain their home effectively. InspectAPedia.com ® author/editor Daniel Friedman is a contributing author. Field inspection worksheets are included at the back of the volume.
Architectural elements: the technological revolution: Galvanized iron roof plates and corrugated sheets; cast iron facades, columns, door and window caps, ... (American historical catalog collection), Diana S Waite, available used out of Amazon.
Green Roof Plants: A Resource and Planting Guide, Edmund C. Snodgrass, Lucie L. Snodgrass, Timber Press, Incorporated, 2006, ISBN-10: 0881927872, ISBN-13: 978-0881927870. The text covers moisture needs, heat tolerance, hardiness, bloom color, foliage characteristics, and height of 350 species and cultivars.
Green Roof Construction and Maintenance, Kelley Luckett, McGraw-Hill Professional, 2009, ISBN-10: 007160880X, ISBN-13: 978-0071608800, quoting: Key questions to ask at each stage of the green building process Tested tips and techniques for successful structural design
Construction methods for new and existing buildings
Information on insulation, drainage, detailing, irrigation, and plant selection
Details on optimal soil formulation
Illustrations featuring various stages of construction
Best practices for green roof maintenance
A survey of environmental benefits, including evapo-transpiration, storm-water management, habitat restoration, and improvement of air quality
Tips on the LEED design and certification process
Considerations for assessing return on investment
Color photographs of successfully installed green roofs
Useful checklists, tables, and charts
Problems in Roofing Design, B. Harrison McCampbell, Butterworth Heineman, 1991 ISBN 0-7506-9162-X (available used)
Roofing The Right Way, Steven Bolt, McGraw-Hill Professional; 3rd Ed (1996), ISBN-10: 0070066507, ISBN-13: 978-0070066502
Slate Roofs, National Slate Association, 1926, reprinted 1977
by Vermont Structural Slate Co., Inc., Fair Haven, VT 05743, 802-265-4933/34. (We recommend this book if you can find it. It
has gone in and out of print on occasion.)
Roof Tiling & Slating, a Practical Guide, Kevin Taylor, Crowood Press (2008), ISBN 978-1847970237, If you have never fixed a roof tile or slate before but have wondered how to go about repairing or replacing them, then this is the book for you. Many of the technical books about roof tiling and slating are rather vague and conveniently ignore some of the trickier problems and how they can be resolved. In Roof Tiling and Slating, the author rejects this cautious approach. Kevin Taylor uses both his extensive knowledge of the trade and his ability to explain the subject in easily understandable terms, to demonstrate how to carry out the work safely to a high standard, using tried and tested methods.
This clay roof tile guide considers the various types of tiles, slates, and roofing materials on the market as well as their uses, how to estimate the required quantities, and where to buy them. It also discusses how to check and assess a roof and how to identify and rectify problems; describes how to efficiently "set out" roofs from small, simple jobs to larger and more complicated projects, thus making the work quicker, simpler, and neater; examines the correct and the incorrect ways of installing background materials such as underlay, battens, and valley liners; explains how to install interlocking tiles, plain tiles, and artificial and natural slates; covers both modern and traditional methods and skills, including cutting materials by hand without the assistance of power tools; and provides invaluable guidance on repairs and maintenance issues, and highlights common mistakes and how they can be avoided.
The author, Kevin Taylor, works for the National Federation of Roofing Contractors as a technical manager presenting technical advice and providing education and training for young roofers.
The Slate Roof Bible, Joseph Jenkins, www.jenkinsslate.com,
143 Forest Lane, PO Box 607, Grove City, PA 16127 - 866-641-7141 (We recommend this book).
Solar heating, radiative cooling and thermal movement: Their effects on built-up roofing (United States. National Bureau of Standards. Technical note), William C Cullen, Superintendent of Documents, U.S. Govt. Print. Off (1963), ASIN: B0007FTV2Q
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