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This article explains how clay tiles are secured to the roof deck. Our page top photo shows clay roofing tiles installed in the Northeastern United States, on a combination steep and low slope roof. The metal tabs exposed at the lower edge of many of these tiles indicates that the roof has had extensive repair work.

Also see CLAY TILE WIND & SEISMIC CONNECTORS where we describe special connections used for clay tiles on roofs in high wind, hurricane, or seismic areas.

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How clay roofing tiles are secured to the roof

Fasteners for clay tile roofs: clay tiles are secured to the roof deck using wire, special clips, concrete, ballast stones, or metal clips. Tiles are secured loosely - overly-tight wires or nails are likely to break the tile.

Also used to secure clay tiles on some roofs are aluminum nails, hot dipped galvanized steel nails, or stainless steel nails. Clay tiles at roof gable edges are often nailed through multiple pre-cast holes in special roof edge tiles in areas where wind blow-off is a common risk. The fastener schedule for clay roofing tiles varies by geographic area, as we discuss below.

Where nails are used, one or two nails per clay tile is usual. In some jurisdictions (areas of low storm and wind damage risk) only every third or fourth course of tiles is nailed, and in the roof shown in our photo (below right) none of the tiles was secured except those at the roof edges where mortar was applied.

Carson Dunlop's sketch (above left) illustrates typical methods of securing clay tiles to the roof deck. The clay tile roof battens shown in the sketch (above left) are discussed at CLAY TILE ROOF BATTENS & STACKING. Our photo (above right) illustrates a clay tile roof undergoing repair in San Miguel de Allende, Mexico.

This tile roof is in a sheltered location and as is local custom, the clay roofing tiles are barely secured, perhaps only at the roof edges where tiles are set in cement.

Here Carson Dunlop's sketch illustrates how the eaves are closed at the lower roof edges where a clay tile roof is installed.

Roof Tile Fastening Alternatives & Methods

Adapted/paraphrased with permission from Best Practices Guide to Residential Construction, chapter on BEST ROOFING PRACTICES:

The preferred method of attachment depends on the type of tile, climate conditions, and slope of the roof.

Loose Laid Clay Tile Roofs

For standard concrete tiles with lugs set on battens, building codes still allow tiles to be laid loose at slopes less than 5:12 (except for one nail per tile within 36 inches of hips, ridges, eaves, or rakes). Loose-laid tiles are not allowed, however, in snow regions, areas subject to high winds, or with tiles weighing less than 9 pounds per square foot installed.

Selection of Nails Used on Clay Tile Roofs

Nails are the least expensive and most common method for attaching concrete and clay tiles. Tiles can be nailed either directly into the roof sheathing or tiles with lugs can be nailed to battens. Corrosion-resistant nails must be minimum 11 gauge, with 5/16 -inch heads, and long enough to penetrate the sheathing by 3/4 inch—typically 8d nails.

Ring-shank nails or hot-dipped galvanized nails hold better than smooth-shank nails in areas subject to heavy winds. Whether driven by hand or pneumatic nailers, nails should be driven so heads lightly touch the tile but not so tight as to risk cracking tiles. Because of the longevity of a tile roof, some contractors use copper or stainless-steel roofing nails. No. 8 or 9 stainless-steel or brass screws also work well and are sometimes used in high-wind regions.

Most tiles have two prepunched nail holes. On curved tiles, use the hole closest to the deck surface unless a nail there would penetrate a critical flashing. The other hole is also used for cut tiles or applications requiring two nails. For example, all flat, non interlocking tiles require two nails. And in snow regions, codes require two nails per tile for all types and slopes. Otherwise follow the guidelines in Table 2-9 above or the manufacturer’s guidelines if they are more stringent.

Also see CLAY TILE WIND & SEISMIC CONNECTORS where we describe special connections used for clay tiles on roofs in high wind, hurricane, or seismic areas.

Tile Roof Fastener 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 fastener options to improve the life of tile roof systems, including

• Copper, grass, or stainless-steel nails, clips, or tie-wire fasteners are recommended
• In areas that are typically hot and dry, corrosion protection need not be as conservative, and galvanized steel (less costly) was found acceptable
• When using galvanized materials, the thickness of the zinc coating was deemed important
• When using galvanized nails they should meet ASTM A 6641
• When fastening tiles directly to plywood or to OSB roof sheathing use ring or screw shank nails

Note: Bliss's fastener suggestions above incorporate and update this historical data. - Ed.

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CLAY TILE ROOFING
  Clay Roofing Tile Types
  CLAY TILE ROOF STYLES, DESIGNS
  CLAY TILE ROOF SPECIFICATIONS
  CLAY TILE ROOF SLOPE, DECK & UNDERLAY
  CLAY TILE ROOF BATTENS & STACKING
  CLAY TILE ROOF CONNECTIONS
  CLAY TILE WIND & SEISMIC CONNECTORS
  CLAY TILE EAVES, HIP & RAKE DETAILS
  FLASHING, CLAY TILE ROOFS
  CLAY TILE ROOF CONNECTIONS
  CLAY TILE WIND & SEISMIC CONNECTORS
  CLAY TILE EAVES, HIP & RAKE DETAILS
  FLASHING, CLAY TILE ROOFS
  CLAY TILE ROOF DAMAGE & WEAR
  ROOFING TILE SHAPES & PROFILES
  CLAY TILE ROOF SUPPLIERS
CLAY, CONCRETE, FIBER CEMENT ROOF TILES

• 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.
• Carson, Dunlop & Associates Ltd., 120 Carlton Street Suite 407, Toronto ON M5A 4K2. (416) 964-9415 1-800-268-7070 info@carsondunlop.com. Thanks to Alan Carson and Bob Dunlop, for permission to use illustrations from their publication, The Illustrated Home which illustrates construction details and building components. Carson Dunlop provides home inspection education including the ASHI-adopted Home Inspection Training Program (home study course), publications such as the Home Reference Book, report writing materials including the Horizon report writer, and home inspection services. Alan Carson is a past president of ASHI, the American Society of Home Inspectors.
• The Carson Dunlop home study course for home inspectors can be examined at the company's website at http://www.carsondunlop.com/Inspectors/hss.htm
• 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. 
• "Design for Long-Lasting Tile Roof Systems", Thomas L.Smith, AIA, CRC, PRofessional Roofing, [ca 1998 Date pending], p. 54
• 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
  

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• 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
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• Concrete Roofing Tile, History of the, Batsford, 1959, AISN B000HLLOUC (availble used)
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• 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.)
• 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
• 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
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