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This article discusses best practices for the installation of asphalt roof shingles on very steep slopes such as on mansard roofs and (though not recommended) on vertical surfaces such as building walls.
Without extra nailing details asphalt shingles are more likely to fail or fall off or be blown off of the very steep roof or vertical wall surface.
Without extra roof shingle tab sealing, asphalt roof shingles on a very steep slope or on a vertical wall surface may fail to seal, resulting in severe wind blow-off damage in storms.
Nevertheless we have on occasion found asphalt roof shingles and occasionally mineral-granule coated roll roofing or even modified bitumen roofing nailed to vertical building walls as a low-cost siding material. Most often roof shingles are used on the walls of a temporary storage shed or clubhouse.
Watch out: If you are going to attempt to install asphalt roof shingles on a very steep slope roof or on a building wall despite these cautions, be sure that you follow the appropriate vertical and near-vertical nailing instructions for the roof shingles that we describe below. Otherwise you'll find them falling off or blowing off of the building.
Referring to slopes of 18" rise in 12" of run (150%) or more, [note that this is more cautious than Bliss's advice found at ASPHALT SHINGLE INSTALLATION] the NRCA (Flickinger) points out that there are differing views within the roofing industry about the maximum slope on which asphalt shingles may be applied using typical methods.
Our steep roof photo (left) shows quite a few shingles lost from this rather steep church roof slope. Flickinger cites the NRCA Roofing and Waterproofing Manual 4th Ed. when he recommends the following steps to be taken when installing asphalt shingles on a very steep (or near vertical) roof slope [probably also helpful if installing shingles on a wall surface]:
18:12 slope shingle application: 6 nails per shingle since on a steep slope more of the shingle's weight is carried by the nails rather than the roof deck
18:12 slope shingle application: Specifications for hand sealing of roof shingles is necessary. At an extreme incline roof shingle's overlapping courses won't apply the necessary pressure to cause the adhesive strips to adequately seal the shingles to the course below.
Hand sealing or "tabbing" roof shingles on a steep slope means applying a dab of sealant (roof cement) under each shingle. For architectural-style laminated shingles use four equally-spaced dabs of sealant under the shingle's leading (lower) edge.
NRCA recommends 3 sealant dabs for 3-tab (cutout type) asphalt shingles, with each spot centered at the bottom of each shingle tab.
ARMA recommends 6 sealant dabs for 3-tab (cutout type) asphalt roof shingles, with a dab at both corners of each shingle tab.
12:12 slope shingle application: (100% slope) and greater: Flickinger notes that some shingle manufacturers require special procedures including extra fasteners and hand sealing on these slopes.
The UBC (Uniform Building Code) and BOCA (Building Officials and Code Administrators International) codes require following the manufacturer's instructions (no kidding, try reading the instructions on the package!) for asphalt shingles installed on the sides of mansard style roofs and on more steep roof slopes.
Underlayment or Sheathing Wrap When Using Asphalt Roof Shingles on Walls
Just as for applying shingles to a roof, underlayment or more properly, housewrap would be recommended for use on wall surfaces just as for most other sidings. The vertical surface of a wall should be sound before installing the
underlayment. Whether or not it is
required, house wrap, and proper flashing details around building openings are reduce the chances of leaks.
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Questions & answers or comments about installing asphalt shingles on very steep roofs or on vertical surfaces & walls.
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GAF Materials Corporation, Grand Timberline Premium Architectural Shingle Application Instructions.
http://www.gaf.com/Content/Documents/20573.pdf discusses the requirements for successful asphalt shingle installation including the condition of the roof deck, the use of roofing felt underlayment, the selection of roofing nails by type and length and penetration of the roof decking, and the role of glue strips on the back side of asphalt roof shingles.
Roofing The Right Way, Steven Bolt, McGraw-Hill Professional; 3rd edition (November 1, 1996), ISBN-13: 978-0070066502, p. 350 for one of many citations on this point.
"Hurricane Damage to Residential Structures: Risk and Mitigation", Jon K. Ayscue,
The Johns Hopkins University, Baltimore, Maryland, published by the Natural Hazards Research and Applications Information Center, Institute of Behavioral Science, University of Colorado, November 1996. Abstract: "Property damage and loss from hurricanes have increased with population growth in coastal areas, and climatic factors point to more frequent and intense hurricanes in the future. This paper describes potential hurricane hazards from wind and water. Damage to residential structures from three recent intense hurricanes - Hugo, Andrew, and Iniki - shows that wind is responsible for greater property loss than water. The current state-of-the-art building technology is sufficient to reduce damage from hurricanes when properly applied, and this paper discusses those building techniques that can mitigate hurricane damage and recommends measures for mitigating future hurricane damage to homes." - online at www.colorado.edu/hazards/publications/wp/wp94/wp94.html
"Evaluating OSB for Coastal Roofs," Paul Fisette, Coastal Contractor, Winter 2005, online at coastalcontractor.net/pdf/2005/0501/0501eval.pdf . Fisette cites: "Jose Mitrani, a civil engineer and professor at Florida. International University in Miami, was ... Florida’s official damage assessment team. ... After Hurricane Andrew, Florida code advisers ruled OSB sheathing inferior to plywood."
ARMA - Asphalt Roofing Manufacturer's Association - http://www.asphaltroofing.org/
750 National Press Building, 529 14th Street, NW, Washington, DC 20045, Tel: 202 / 207-0917
ASTM - ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA, 19428-2959 USA The ASTM standards listed below can be purchased in fulltext directly from http://www.astm.org/
NRCA - National Roofing Contractors Association - http://www.nrca.net/, 10255 W. Higgins Road, Suite 600,
Rosemont, IL 60018-5607, Tel: (847) 299-9070 Fax: (847) 299-1183
"Applying Shingles on Extreme Slopes", Dave Flickinger, RRO, Professional Roofing, July 1999. [PDF copy] - National Roofing Contractors Association - http://www.nrca.net/,
10255 W. Higgins Road,
Rosemont, IL 60018-5607,
Tel: (847) 299-9070
Fax: (847) 299-1183,
Office hours: 8 a.m. to 5 p.m. CST
UL - Underwriters Laboratories - http://www.ul.com/
2600 N.W. Lake Rd.
Camas, WA 98607-8542
Tel: 1.877.854.3577 / Fax: 1.360.817.6278
Books & Articles on Building & Environmental Inspection, Testing, Diagnosis, & Repair
The Home Reference Book - the Encyclopedia of Homes, Carson Dunlop & Associates, Toronto, Ontario, 25th Ed., 2012, 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. Field inspection worksheets are included at the back of the volume. Special Offer: For a 10% discount on any number of copies of the Home Reference Book purchased as a single order. Enter INSPECTAHRB in the order payment page "Promo/Redemption" space. InspectAPedia.com editor Daniel Friedman is a contributing author.
Or choose the The Home Reference eBook for PCs, Macs, Kindle, iPad, iPhone, or Android Smart Phones. Special Offer: For a 5% discount on any number of copies of the Home Reference eBook purchased as a single order. Enter INSPECTAEHRB in the order payment page "Promo/Redemption" space.
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
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).