Key design details & references for wood shingle roofs
Questions & answers about signs of wear or damage to wood shingle or wood shake roofs
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Here we discuss the inspection of wood shingle or wood shake roofing for indications of wear, poor installation, or other troubles that affect the remaining life of a wood shingle roof, wood shake roof, cedar shingle or cedar shake roof.
Examples of Wood Roof Wear or Installation Problems that Limit Roof Life
Worn out wood shingle roofs: Our photo of a worn-out, curling, thin, split wood shingle roof is at above left. That's pretty easy to estimate.
Wood shingle placement & side lap offset: Take a close look at the new wood shingle roof at right. The side lap offset on this roof looks as if it barely complies with the 1.5" offset we want to see - it might be an improper installation, with many shingle butt joints offset by as little as 3/16" over one another. If so, this roof is likely to be leaky and it was not installed according to industry specifications. A closer look is needed.
At Anecdote of a "Bad" Roofing Contractor we give details about another case of improper nailing pattern for wood shingle roofs. In three successive courses of wood shingles or shakes, no butt joints should be in direct alignment (joints over joints), and between any two adjacent shingle courses the side lap offset of shingles over the course below should be 1 1/2" or more.
Wood shingle side gaps: Wood shingles are nailed with a 1/4" to 3/8" gap between adjacent shingles to accommodate shingle movement and dimensional change when shingles are wet by rain or melting snow. Omitting this gap can lead to a buckling, splitting, and failed wood shingle roof. Wood shakes require a still larger gap of 3/8" to 5/8" separation. More details are at WOOD ROOF INSPECTION GUIDE.
More Wood Shingle Roof Details & Indications of Wood Roof Trouble
Our photo of a moss-overgrown wood shingle roof is at above left. Additional examples of moss and lichens growth on roofs as well as discussion of how to remove and prevent this problem are at ALGAE, FUNGUS, LICHENS, MOSS on SHINGLES.
Our photo of a curling and splitting wood shingle roof at above right demonstrates early wear and damage that might occur when wood shingles are installed over un-vented solid plywood decking.
Carson Dunlop's sketch at left shows an alternative method for providing (some) ventilation under cedar shingles when applied over a solid plywood roof deck. In our OPINION, installing wood shingles over un-vented solid plywood decking cuts the roof life in half, but this vent product might extend wood shingle life.
Carson Dunlop's sketch (below left) illustrates the traditional cedar shingle application pattern on spaced plank sheathing - a design that allows the shingles to dry quickly, extending the roof life. Our photo (below right) shows this traditional wood shingle roof installation at which the shingles were nailed on spaced sheathing, affording good ventilation.
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).
Questions & Answers regarding this article
Questions & answers about signs of wear or damage to wood shingle or wood shake roofs.
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Problems in Roofing Design, B. Harrison McCampbell, Butterworth Heineman, 1991 ISBN 0-7506-9162-X (available used)
Cedar Shake & Shingle Bureau, CSSB, U.S.: Sumas, WA 98295-1178, Tel: 604-820-7700, In Canada:
Cedar Shake and Shingle Bureau #2 - 7101 Horne Street, Mission, BC V2V 7A2 Tel: (604) 820-7700, E-mail: info@cedarbureau.com , website: http://www.cedarbureau.org/
CCSB offers wood shingle installation instructions in the form of a manual - cedarbureau.org/installation/wall_manual/introduction.htm
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. 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
"Weather-Resistive Barriers [copy on file as /interiors/Weather_Resistant_Barriers_DOE.pdf ] - ", how to select and install housewrap and other types of weather resistive barriers, U.S. DOE
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