WOOD ROOF INSTALLATION SPECS - CONTENTS: Pitch or slope requirements for wood roofs. Nailing schedule for wood shingles/shakes. What types of nails or staples are used with wood shakes or wood shingles? What is the proper nailing pattern for wood shingle or wood shake roofs. Wood shingle exposure length table. Notes on side-lap wood shingle roofs.
This wood roof article describes the slope and exposure requirements for wood shake or wood shingle roofs, and provides detailed instructions on how and where to nail or fasten wood shingles/shakes on roofs.
Recommended exposures for shakes and shingles on roofs are
shown in Tables 2-13 and 2-14.
Minimum slopes. The minimum recommended slope
for standard installation of shingles is 3:12, and 4:12
Low slopes. On lower slopes, shingles or shakes may
be installed over a fully waterproof built-up roof
(BUR) or membrane roof. Over the membrane, install
vertical 2x4 battens lined up with the rafters, then
spaced sheathing as described below.
Climate factors. In warm, high-moisture climates, lowslope
wood roofs need extra maintenance, particularly
in areas with overhanging trees.
If pine needles, leaves,
or other organic debris is allowed to accumulate on a
shaded section of the roof, moss, lichen, and algae
will grow and retain moisture. This, in turn, will lead
to premature curling, splitting, and decay of the
shakes or shingles.
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 Roof Shingle Exposure Specifications
Shingle exposures for wood roofs: the maximum weather exposure for wood shakes or wood shingles depends on the shingle size and the slope or pitch of the roof.
Allowable shingle exposure may also vary by the shingle grade - something that you might infer by visual inspection of the shingles, matching against wood shingle grade definitions, or if a shingle identification label can be located.
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 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 Shingle 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 Shingle 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).
Eaves Flashing Details for Wood Shingle & Shake Roofs
Apply eaves flashing to either spaced
or solid sheathing in regions with an average daily temperature
of less than 25°F (under the IRC) or in other areas
prone to ice and snow buildup.
The eaves flashing should
extend up the roof to a point 24 inches inside the building.
Where eaves flashing is required with spaced sheathing,
install solid sheathing along the bottom section of the roof
to support the eaves flashing.
Fastener Specifications for Wood Shingle & Shake Roofs: Nails, Staples
All nails should be either stainless steel (type 304 or 316),
hot-dipped galvanized, or aluminum. Staples should be
either stainless steel or aluminum. Galvanized staples will
not last the life of the roof.
Treated wood roof shingles may require
stainless steel or other special fasteners. Consult with the
treatment company for recommendations. Stainless steel
is also the first choice in coastal environments.
Nails used with wood shingles or shakes should be box type and penetrate the sheathing
inch (Table 2-15 above/left)
Staples used on wood shingles or shakes should have crowns between 7/16
wide and penetrate the sheathing by
Drive wood shingle nails flush. Do not drive nail heads or staple
crowns below the surface of the shingle.
Underdriving or overdriving weakens the shingle
Placement of wood shingle nails. Each shake or shingle should receive only
two nails. Place one fastener
3/4 inch in from each edge and
1/2 inches above the exposure line (Figure 2-50 below).
Wood Shingle Installation Specifications
Whether installed over solid sheathing or spaced sheathing,
follow these guidelines:
For the starter course, double or triple the shingles in
the first row.
Each shingle gets two nails about
-inch in from each
end, and 1
inches above the butt line of the overlaying
The first course should overhang the fascia by
inches. All courses should overhang the rake
by about 1 inch.
Leave a gap of
inch between adjacent shingles
for expansion when wet.
Offset joints in successive courses by at least 1
inches (Figure 2-50 shown just above). Also, no more than 10% of joints
should line up with joints in alternate courses (two
Flat-grain shingles wider than 8 inches should be split
into two shingles before installing.
Treat knots, similar defects, and centerline of heart as
if they were joints between shingles, and locate the
inches from joints in the row above or below.
Wood Shake Roof Installation Specifications: Felt Interlay or Felt Underlayment
In order to restore some of
Pennsylvania’s historic buildings,
the authors are recovering a lost
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.
these attempts have saved money and
time in the short term but have failed to
perform long enough to realize the
Continue reading at WOOD ROOF FLASHING DETAILS or select a topic from closely-related articles below, or see our complete INDEX to RELATED ARTICLES below.
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(Dec 7, 2012) Jarod said:
Is it okay to install a roof paper, then cedar breather when using shakes? I see details showing the felt underlay method. How time consuming.
(Apr 1, 2014) phil said:
Can I install red cedar shingles on roof with 1/2 plywood or should I add 1x6 strapping on plywood and then
install cedar shingles?
Jarod and Phil,
From what I've learned of this topic, codes permit installing wood shingles atop solid plywood roof decking but in my field experience I see early failures where the roof is poorly vented. In my OPINION a better roof job uses strapping to allow airflow beneath the shingles.
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Questions & answers or comments about wood shingle and wood shake roofs: installation, inspection, troubleshooting, maintenance, & replacement.
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Mark Cramer Inspection Services Mark Cramer, Tampa Florida, Mr. Cramer is a past president of ASHI, the American Society of Home Inspectors and is a Florida home inspector and home inspection educator. Mr. Cramer serves on the ASHI Home Inspection Standards. Contact Mark Cramer at: 727-595-4211 mark@BestTampaInspector.com
John Cranor is an ASHI member and a home inspector (The House Whisperer) is located in Glen Allen, VA 23060. He is also a contributor to InspectApedia.com in several technical areas such as plumbing and appliances (dryer vents). Contact Mr. Cranor at 804-747-7747 or by Email: firstname.lastname@example.org
"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)
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: email@example.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
"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
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).
Carson, Dunlop & Associates Ltd., 120 Carlton Street Suite 407, Toronto ON M5A 4K2. Tel: (416) 964-9415 1-800-268-7070 Email: firstname.lastname@example.org. The firm provides professional home inspection services & home inspection education & publications. Alan Carson is a past president of ASHI, the American Society of Home Inspectors. Thanks to Alan Carson and Bob Dunlop, for permission for InspectAPedia to use text excerpts from The Home Reference Book & illustrations from The Illustrated Home. Carson Dunlop Associates' provides extensive home inspection education and report writing material.
The Illustrated Home illustrates construction details and building components, a reference for owners & inspectors. Special Offer: For a 5% discount on any number of copies of the Illustrated Home purchased as a single order Enter INSPECTAILL in the order payment page "Promo/Redemption" space.
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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.
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