Key design details & references for preservative coatings & fire resistive coatings used on wood shingle roofs
Questions & answers about preservative coatings & fire resistive coatings used on wood shingle roofs
Coatings for wood shingles or wood shake roofs - wood roof preservatives, wood roof fire resistive coatings: This article explains fire resistant treatments and preservative treatments for wood shingle or wood shake roofing in historic and contemporary use.
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More details useful for determining the condition of a wood roof are at WOOD ROOF INSPECTION GUIDE. More about wood coatings and about cleaning wood shingle or shake roofs is found at WOOD ROOF MAINTENANCE.
Protective Coatings & Treatments for Fire Rating for Wood Shingle & Wood Shake Roofs - Getting from No-Rating to B-Rating to Class A Fire Rating
Types of Wood Shingle/Shake Roof Treatments Available
As we mention in our outline of roofing materials and their properties found at ROOFING INSPECTION & REPAIR, wood shingle roofs, if treated with a fire retardant, are fire rated B. Un-treated wood roof shingles have no fire rating and are not permitted by code in some areas. A class A fire rated wood shingle roof can be installed using special procedures and materials that include plywood and gypsum board.
NRCA's David Flickinger explained in 1999 in Professional Roofing, that treatments are available for wood shingles and wood shakes on building roofs to preserve the wood from rot and to increase its fire resistance. For new wood shingles, a pressure treatment impregnates the shingles with a wood preservative (in the 1990's CCA or chromated copper arsenate) or a fire retardant.
When shingles are treated with a fire retardant they are then heated to complete that treatment procedure.
Typical spray or brush-on wood roof treatments are also available to treat wood shingles or shakes that have already been installed on a building.
According to Flickinger, the Cedar Shake & Shingle Bureau (CSSB) recommends that cedar roofing products used in locations with high decay potential should be treated with a preservative.
A U.S. map provided by the Forest Products Laboratory (above-left) indicates that the southeastern quadrant of the U.S., but extending north into West Virgina and parts of eastern Kentucky and Tennessee make up this area of high decay hazard (the dark colored area on the map) based on the FPL climate index.
Questions About the Durability of Fire Retardants & Preservatives for Wood Roofs
According to the NRCA both of the wood roof processes described above, when wood roofing shingles or shakes are treated under pressure, before installation on the roof, are considered "permanent", that is, the treatment should last for the life of the wood shingle.
For existing wood shingle roofs, treatment might be applied using a topical spray or brush-on of preservatives. These treatments are not permanent and need to be performed periodically depending on the geographic locale of the roof
Where premium red or white
cedar is too expensive for a particular roofing job, wood roof buyers should consider pressure-treated southern
yellow pine shakes and shingles. In its favor, yellow pine
is a tougher and stronger wood, and although not as pretty
as red cedar when new, over time they will both weather to
a similar silver gray.
Because penetration of the treatment on pine roofing shingles
is nearly 100%, pressure-treated pine shingles carry guarantees
against decay for up to 50 years, making them well suited
to high-moisture environments, shallow slopes, and
shady wooded sites where organic matter may collect on
the roof. The preservatives should not leach out over time.
One drawback to yellow pine shingles and shakes is
that many are flat-grained, so most come pretreated with a
water repellent to help them resist cupping and splitting.
However, retreatment with a water repellent at some point
may be required for optimal performance. Western red
cedar shingles are also available pressure-treated for
severe applications where standard cedar shingles are
prone to decay.
A bit before Flickinger's 1999 article, in 1995 in his article on Choosing Roofing, Jefferson Kolle questioned the durability of wood shingle fire retardant treatments. Kolle suggested that rain tends to draw the fire retardant to the shingle surface where it is washed away over time.
The same article however, quoted Don Meucci from the Cedar Single & Shake Bureau who said that tests performed on fire-retardant-treated wood shingles from a 16-year old roof passed the current fire resistance tests of that time. Nonetheless, some communities where fire risk is particularly high (Los Angeles California, Newcastle, New Hampshire) have banned the use of wood roofs regardless of their treatment.
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 preservative coatings & fire resistive coatings used on wood shingle roofs.
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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 CCSB offers wood shingle installation instructions in the form of a manual - cedarbureau.org/installation/wall_manual/introduction.htm
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
Forest Products Laboratory, US FPL, One Gifford Pinchot Drive, Madison, WI 53726, Tel: (608) 231-9200, Email: mailroom_forest_products_laboratory@fs.fed.us608-231-9200, website: http://www.fpl.fs.fed.us/
NRCA - National Roofing Contractors Association - http://www.nrca.net/, 10255 W. Higgins Road, Suite 600,
Rosemont, IL 60018-5607, Tel: (847) 299-9070
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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When shingles are treated with a fire retardant they are then heated to complete that treatment procedure. 