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Clay Tile Roof Slope, Sheathing, & Underlayment Specifications
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Clay tile roof slope, sheathing, underlayment specifications: this article describes the requirements & specifications for clay tile roof installation: roof slope, roof sheathing,m and clay tile roof underlayment.
This article series discusses best practices in the selection and installation of residential roofing. This article includes excerpts or adaptations from Best Practices Guide to Residential Construction, by Steven Bliss, courtesy of Wiley & Sons.
Also see our clay roof tile home page CLAY TILE ROOFING and see CLAY TILE ROOF STYLES, DESIGNS for detailed descriptions of different clay roof tile styles and characteristics, and see ROOFING TILE SHAPES & PROFILES for the basics of roof tile profiles and what they mean.
Green links show where you are. © Copyright 2013 InspectAPedia.com, All Rights Reserved. Author Daniel Friedman.
Tile-Covered Roof Slope Specifications
Adapted/paraphrased with permission from Best Practices Guide to Residential Construction, chapter on BEST ROOFING PRACTICES:
Roof Slope Requirements for Tiled Roofs
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 Most manufacturers recommend minimum slope requirements
for their tiles as well as special underlayment and
fastening techniques for low-slope installations.
Typical
minimums are shown in Table 2-5. Some manufacturers
allow specific tile types to be installed on roofs as shallow
as 2 1/2 :12 if a full waterproofing layer, such as a built-up
roof or single-ply membrane, is installed.
Reduced exposure
and special fastening techniques may also be required
for low slopes.
On slopes less than 3 1/2 :12, roofing tile is
considered decorative only. The underlying roof provides
all the necessary waterproofing.
In general, there is no maximum slope for tile roofs.
However, on extremely steep roofs above 19:12 or on vertical
applications, wind currents may cause tiles to rattle.
To avoid this, use wind clips on each tile along with a
construction grade silicone sealant or other approved
sealant.
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Roof Sheathing Requirements for Tiled Roofs
While spaced sheathing is allowed under the codes, most
installations today are done on solid wood sheathing with
or without battens. The sheathing must be strong enough
to support the required loads between rafters. Minimum
requirements are nominal 1 inch for board sheathing or
15/32 for plywood and other approved panel products.
Underlayment Requirements for Clay Tiled Roofs
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Because of the long service life of tile, a long-lasting underlayment
should be used as well. Underlayments play a
key role in tile roofing, since most tile roofs are not completely
waterproof.
At a minimum, use a Type II No. 30 or
No. 43 felt, lapped 2 inches on horizontal joints and
6 inches at end laps. The underlayment should lap over
hips and ridges 12 inches in each direction and turn up vertical
surfaces a minimum of 4 inches (Figure 2-20).
At tricky areas, such as around roof vents, chimneys,
and skylights, self-adhesive bituminous membrane can
help achieve a watertight seal.
In windy areas, use tin caps
or round cap nails to hold the underlayment securely. The
fastening schedule for the underlayment will depend on
local wind conditions.
For harsher conditions or shallower slopes, use mineral surface
roll roofing, self-adhering bituminous membrane, or
other durable waterproofing systems.
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For slopes below
3-1/2:12 the underlayment must provide complete weather
protection, and the tiles are considered merely decorative.
Underlayment recommendations for different types of tiles
and climate conditions are shown in Table 2-6, Table 2-7, and Table 2-8 below. [Click to enlarge any tables or images in these articles.]
Tile Roof Underlayment Options from NRCA
In the 1990's NRCA's Thomas Smith noted that a paper published in the Proceedings of the 10th Conference on Roofing Technology expressed concern for the lack of conservative roofing industry guidelines for the components of tile roofing systems in the U.S.
The recommendations in the then-current NRCA Steep Roofing and Waterproofing Manual indeed included recommendations for tile roof underlayment, fasteners, and metal flashings, but Smith noted that these were "non-conservative" for many areas in the United States (and other locations of challenging weather). Smith posed some interim underlayment options to improve the life of tile roof systems, including for 4" in 12" or greater (steeper) sloped tile roofs:
- A single layer of organic smooth-surfaced roll roofing meeting ASTM D 224 Type I or II (II is preferable)
- Two layers of coated organic base sheet meeting ASTM D 2626 (un perforated)
- Two layers of organic felt meeting ATM D226 Type II (30 pound felt) over 1 layer of ASTM D226 Type I (15 pound felt)
- One layer of self-adhering modified bitumen meeting ASTM D 1970, over one layer of ASTM D226 Type I (15 pound felt) to make it easier to later remove self-adhering underlayment and reducing moisture damage to the deck
- One layer of self-adhering modified bitumen underlayment meeting ASTM D 1970, under one layer of ADTM D 226 Type II 30 pound felt
- Certain types of SBS modified bitumen, heavyweight sheets may also be good underlayments, but Smith noted that until ASTM standards were developed, specifying those products was difficult.
Special provisions were needed for lower slope roofs (under 4" in 12")
-- Adapted with permission from Best Practices Guide to Residential Construction.
Resources: Roofing Materials & Equipment Suppliers
Manufacturers
Concrete Roof Tiles
Bartile Roofs
www.bartile.com
Eagle Roofing Products
www.eagleroofing.com
Entegra Roof Tile
www.entegra.com
MonierLifetile
www.monierlifetile.com
Vande Hey-Raleigh
www.vhr-roof-tile.com
Westile
www.westile.com
Clay Roof Tiles
Altusa, Clay Forever LLC
www.altusa.com
Ludowici Roof Tile
www.ludowici.com
MCA Clay Tile
www.mca-tile.com
U.S. Tile Co.
www.ustile.com
Tile Fasteners and Adhesives
Dow Building Products
www.dow.com/buildingproducts
Tile Bond polyurethane foam tile adhesive
Fomo Products
www.fomo.com
Handi-Stick polyurethane foam tile adhesive
Newport Fastener
www.newportfastener.com
Twisted wire systems, hurricane clips, nose clips,
and the Tyle-Tye TileNail
OSI Sealants
www.osisealants.com
RT 600 synthetic rubber tile adhesive
Polyfoam Products
www.polyfoam.cc
Polyset and Polyset One polyurethane foam
tile adhesives
Wire works, Inc.
www.wireworks-inc.com
Tile hooks, hook nails, copper and stainless-steel nails
More Information about Roofing Materials, Methods, Standards
Asphalt Roofing Manufacturers Association (ARMA)
www.asphaltroofing.org
Cedar Shake and Shingle Bureau
www.cedarbureau.org
Metal Roofing Alliance
www.metalroofing.com
Tile Roofing Institute
www.tileroofing.org
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-- Adapted with permission from Best Practices Guide to Residential Construction.
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Technical Reviewers & References
Related Topics, found near the top of this page suggest articles closely related to this one.
- 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
Fax: 202 / 223-9741
- "Design for Long-Lasting Tile Roof Systems", Thomas L.Smith, AIA, CRC, PRofessional Roofing, [ca 1998 Date pending], p. 54
- 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
- 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
E-mail: cec.us@us.ul.com
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.
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- Best Practices Guide to Residential Construction, by Steven Bliss. John Wiley & Sons, 2006. ISBN-10: 0471648361, ISBN-13: 978-0471648369, Hardcover: 320 pages, available from Amazon.com and also Wiley.com. See our book review of this publication.
- Decks and Porches, the JLC Guide to, Best Practices for Outdoor Spaces, Steve Bliss (Editor), The Journal of Light Construction, Williston VT, 2010 ISBN 10: 1-928580-42-4, ISBN 13: 978-1-928580-42-3, available from Amazon.com
- The Journal of Light Construction has generously given reprint permission to InspectAPedia.com for this article. All rights and contents are ©Journal of Light Construction and may not be reproduced in any form.
- 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.
- Asphalt Roofing Residential Manual,
- Building Pathology, Deterioration, Diagnostics, and Intervention, Samuel Y. Harris, P.E., AIA, Esq., ISBN 0-471-33172-4, John Wiley & Sons, 2001 [General building science-DF] ISBN-10: 0471331724
ISBN-13: 978-0471331728
- Building Pathology: Principles and Practice, David Watt, Wiley-Blackwell; 2 edition (March 7, 2008)
ISBN-10: 1405161035
ISBN-13: 978-1405161039
- Built-Up Roof Systems, Manual, C.W. Griffin, Mcgraw-Hill (Tx); 2nd edition (July 1982), ISBN-10: 0070247838, ISBN-13: 978-0070247833
- Concrete Folded Plate Roofs, C. Wilby PhD BSc CEng FICE FIStructE (Author), Butterworth-Heinemann, 1998, ISBN-10: 0340662662, ISBN-13: 978-0340662663
- Concrete Shell Roofs, C. Wilby PhD BSc CEng FICE FIStructE (Author),
- Concrete Dome Roofs (Longman Concrete Design and Construction Series),
- Concrete Roofing Tile, History of the, Batsford, 1959, AISN B000HLLOUC (availble used)
- Copper Roofing, by CDA
- Copper Roofing, Master specifications for copper roofing and sheet metal work in building construction: Institutional, commercial, industrial, I.E. Anderson, 1961 (hard to find)
- Corrugated Iron, Building on the Frontier, Simon Holloway
- 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
- Handbook of Building Crafts in Conservation, Jack Bower, Ed.,
Van Nostrand Reinhold Company, NY 1981 ISBN 0-442-2135-3 Library of
Congress Catalog Card Nr. 81-50643.
- Historic Preservation Technology: A Primer, Robert A. Young, Wiley (March 21, 2008)
ISBN-10: 0471788368
ISBN-13: 978-0471788362
- Historic Slate Roofs : With How-to Info and Specifications, Tina Skinner (Ed), Schiffer Publishing, 2008, ISBN-10: 0764330012
, ISBN-13: 978-0764330018
- Low Slope Roofing, Manual of, 4th Ed., C.W. Griffin, Richard Fricklas,
McGraw-Hill Professional; 4 edition, 2006, ISBN-10: 007145828X, ISBN-13: 978-0071458283
- Roof failure causes in depth (and specific methods for avoiding them)
- Roof design fundamentals and flourishes, based on voluminous industry research and experience
- New technologies and materials -- using them safely and correctly
- Comprehensive coverage of all major roofing systems
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- Metal Roofing, an Illustrated Guide, R.A. Knowlton , [metal shingle roofs],
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- 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).
- Slate Roofing in Canada (Studi4es in archaeology, architecture, and history),
- Smart Guide: Roofing: Step-by-Step Projects, Creative Homeowner (Ed), 2004, ISBN-10: 1580111491, ISBN-13: 978-1580111492
- 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
- Tile Roofs of Alfred: A Clay Tradition in Alfred NY
- "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
- Wood Shingle Roofs, Care and Maintenance of wood shingle and shake roofs (EC), Stanley S. Niemiec (out of print)
- ...
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